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The interplay between bottom-up and top-down processes underlying pre-reflective and reflective sense of agency: An integrative approach
Sense of agency is commonly defined as the sense that one is the author of one?s actions and their consequences. The underlying mechanisms have long been ignored until certain disorders and experimental cases proved it necessary to develop an understanding of how we normally experience agency. Two major accounts have been proposed to address this issue. The predictive account underlines the role of intrinsic and sensorimotor cues, whereas the inferential account posits the contribution of extrinsic cues and high level inferences. The present study is an attempt to combine the two views in the light of the integrative approach that accommodates a dynamic relationship between intrinsic and extrinsic cues. We therefore conducted two multi-phased experiments to examine the purported role of multiple cues in both pre-reflective (intentional binding) and reflective (subjective judgments) sense of agency. In Experiment 1, we found that the congruency between subliminal primes (extrinsic cues) and the predictions (intrinsic cues) influenced the intentional binding effect. In Experiment 2, we rendered the source of the action-outcomes ambiguous. The results showed that the consistency between predictions and actual outcomes of an action along with the time interval between actions and outcomes are important determinants of explicit judgments of agency. We conclude that the underlying mechanism of the sense of agency, in both pre-reflective and reflective forms, has a complex nature and operates upon multiple agency cues.
Acquisition of past tense in Albanian: Implications for morphological processing and representation
This study examines the acquisition of past tense in Albanian, which is a highly inflectional language, especially with respect to its verbal system. The past tense depicts a rather complex picture, involving several components and discrepancies. This process is realized via mandatory suffixation (two suffixes available for the third person singular: `-i? and `-u?), accompanied by the different combinations of two other inflectional dimensions: stem extension (four available affixes for the third person singular: `-v-?, `-t-?, `-jt-?, `-r-?), and stem change. Unlike English, Albanian doesn?t offer a clear distinction between `regular? and `irregular? inflection, and a `default-like? past tense process. Rather, it involves several discrepancies between verbs? past tense formation and their phonological structure, such that verbs belonging to the same phonological prototype diverge with respect to their past tense formation. Also, it is one of a limited number of languages that offers the possibility to observe paradigmatic relations and discrepancies between a verb?s inflected instances.The present study deals with production data, collected from 64 monolingual Albanian-speaking children divided into three age groups (age range: 2,8 ? 5,8). A picture-cued elicitation technique was used to elicit children?s production of the verbs? present and past tense forms, of which only the past tense productions were coded and statistically analyzed. Verbs from different phonological neighborhoods were included, where special attention was paid towards including verbs for each different past tense process, and verbs from the same phonological prototype, that diverged with respect to their past tense formation.The findings reveal a pronounced tendency of children, regardless of age, to overapply the `-v-? stem extension affix, which is consistently present in the first and second person singular past tense instances of the related verbs, to the third person singular, an instance which is never observed in adult language. This phenomenon suggests effects of paradigmatic analogy. Another major pattern observed was the overgeneralization of a past tense process to verbs that actually employ another past tense formation process. This pattern occurred with verbs whose present tense forms belong to the same phonological neighborhood, therefore indicating effects of phonological similarity on children?s processing of the past tense.The results are discussed with particular attention paid to the accumulating evidence on paradigmatic effects and the analogy between words sharing morpho-phonological and / or semantic properties. We conjecture that the `v-stem extension overgeneralization? pattern displayed by the Albanian-speaking children is a peculiar phase during their acquisition of the past tense, which promotes their transition to the adult level of processing and representation of this challenging morphological process. Our findings favor morphological processing models in which analogy to other exemplars and intrinsic relations between words play a crucial role.
Frequency effects in the processing of morphologically complex Turkish words
This is an empirical study that examines how morphologically simple and complex words in Turkish are represented in the brains of native speakers. Two experiments are reported that use various "frequency of occurrence" metrics as independent variables. The secondary findings of the study are that (a) frequency is an extremely complex concept, especially in the case of an agglutinating language like Turkish; (b) different frequency measures are highly correlated; (c) frequency distributions are uneven at several levels; (d) the overwhelming majority of grammatically possible forms are never used even in a large corpus; (e) in an agglutinating language like Turkish, morphology has a deep impact even at sub-lexical levels such as the distribution of letter-ngrams; (f) conducting psycholinguistics experiments online rather than in a laboratory environment is a feasible option; (g) letter shape does not have an effect on word recognition accuracy; (h) morphologically complex Turkish words are processed two times more slowly than simple words, suggesting that suffix sequences add a significant workload to the recognition process. The three main findings of the experiments, on the other hand, are that (a) more frequent simple words are processed faster than less frequent simple words, thus replicating a well-established finding in a typologically different language; (b) complex words are probably processed from left to right, and, most importantly, (c) the human brain can use suffix sequences to recognize complex words, thus suggesting that there exist mental representations for frequently occurring suffix sequences, probably in addition to mental representations for individual suffixes.
An experimental and computational model of rat-robot interaction
Recent advancements in robotics and artificial intelligence have led to an increased incorporation of robots in animal research. Various robotic systems have been employed as modern alternatives to the traditional Skinner box, used in teaching operant conditioning tasks to animals and enhancing the learning of complex behavioral tasks. Parallel to this, there is a growing trend of using animals in AI research for the training and refinement of algorithms and models. In these experiments, learning is unidirectional, where either the robot or the animal plays the role of the teacher, and the other, the learner. In this study, we introduce an innovative animal-robot interaction framework that facilitates bidirectional, or mutual, learning between a Wistar rat and a robotic agent. The interaction involved both agents working towards set objectives, modifying their behaviors in response to the partner's signals. This mutual learning paradigm was examined both in silico with two artificial reinforcement learning agents and in vivo with Wistar rats and a physical robot. In the virtual environment, the agents successfully adapted their behaviors to optimize rewards and achieved mutual learning. The in vivo experiments demonstrated that rats quickly learned behaviors necessary for reward acquisition and showed avoidance learning for negative signals, particularly when the robot exhibited rapid learning progress. When either partner was unable to learn, the other's learning was also hindered. This paradigm offers a novel approach for diverse animal-machine interactions, assessing the effectiveness of different learning rules and algorithms in achieving mutual learning between agents.
Audio-visual saliency in omnidirectional panoramic scenes
As virtual reality devices become more widespread, investigating how humans explore omnidirectional panoramic scenes has become a topic of interest. Several computational models now exist for predicting visual saliency in such environments. However, the existing literature largely ignores auditory cues while estimating saliency maps. To pave the road for more capable models, we investigate how scene attributes and sound categories influence visual exploration. In that manner, how several semantic categories for audio and places influence observer saliency and how such effects differ across different color and audio modulations are investigated by conducting an experiment and creating a novel eye-tracking dataset. Analyses revealed that when viewing 360° videos freely, observer exploration behavior completely changed across different audio categories. The presence of audio, irrespective of whether it contained spatial features, strongly guided this exploration behavior. Color information did not necessarily have a similar effect. Furthermore, the effects of task type over eye fixations were explored by conducting a psychophysics experiment via presenting participants with simple three-dimensional audio-visual stimuli across free viewing, search, and memory recall tasks where the stimuli differed by colors. Overall, analyses revealed that neither of the modulated features had any effect except color contrast levels, hinting that only the task-relevant features play a role in eye fixations in the presence of a task.
The acquisition of prosodic focus and clefts in Turkish
This thesis explored Turkish-speaking children's comprehension of prosodic focus and clefts. Experiment 1 examined preschoolers' comprehension of prosodic focus concerning subject and object-focused sentences. Results indicate that children perform significantly better in object-focused sentences than subject-focused ones until age five. Thus, Turkish-speaking children comprehend the prosodic focus gradually and perceive the object focus as default in the early years of development. Experiment 2 considered the effects of pragmatic felicity, age, and cleft type on cleft comprehension. The findings demonstrate that Turkish-speaking children achieved a high level of competence in interpreting both types of clefts regardless of the factors. Experiment 3 aimed to understand whether the methodology used in Experiment 2 impacted children's performances and explored their comprehension with a more complex experimental paradigm. Results of Experiment 3 provided more evidence that Turkish-speaking children can comprehend both cleft types at a similar accuracy level. In conclusion, this research suggests that Turkish-speaking children exhibit differences in comprehension of prosodic focus and cleft structures. The acquisition of prosodic focus predisposes an object advantage. There is no asymmetry in the cleft acquisition process. Our experiments demonstrate that Turkish's unique syntactic characteristics significantly affect children's language acquisition process, and they allow children to employ different strategies to comprehend subject- and object-clefts. Consequently, this thesis is notable for being the first attempt to examine Turkish prosodic focus and cleft sentence structures, and it serves as a comprehensive foundation for future research.
Behavioral effects of repetitive exposure to brief environmental enrichment in wistar rats
Environmental enrichment and deprivation are well-studied intervention models that impact sensory-motor experiences and lead to a range of behavioral, neural, and molecular effects in rodents. Enriched environments often boost cognitive functions, modify affective behaviors, and help alleviate neurological pathologies through various plasticity processes. In contrast, social isolation typically leads to adverse effects on the cognitive and emotional systems of rodents. These environmental conditions are often investigated under either short-term or prolonged exposures. Here, I investigated the behavioral and neural consequences of intermittent enrichment or isolation. I used twenty-four Wistar rats, dividing them into three groups as enriched (EC), impoverished (IC), and standard condition (SC). The 8-week-long protocol involved moving EC rats to enriched cages and IC rats to individual isolation cages for two days after a five-day period in standard housing. As a result, EC rats exhibited behavioral despair while it produced a profound anxiolytic effect. Intermittent enrichment transiently improved spatial memory, which was not maintained in subsequent trials or the probe test of Morris water maze. Immunohistochemical analysis of parvalbumin (PV) indicated fewer parvalbumin-immunopositive (PV+) cells in the CA1 region of IC rats compared to the EC and SC groups. IC rats also had reduced PV+ cells in the CA3 and dentate gyrus as compared to EC rats. No differences in PV+ cell counts were noted in the lateral or basolateral amygdala. These results highlight that intermittent periods of enrichment and deprivation are sufficient to induce significant behavioral and neural changes.
Emergence of negation in a Turkish homesign system: Insights from the family context
The homesign systems, which are gestural communication invented by deaf individuals without access to any conventional language input (Goldin-Meadow, 2003), provide a unique context to comprehend what characteristics are fundamental in human language. The fact that these systems presented various characteristics of conventional languages in lack of a model raised questions about whether interlocutors of homesigners present any structure with their gestures. In the current study, I focused on a homesign system used by a Turkish homesigner child, Deniz, and his mother and sister. Specifically, I investigated the negation gesture patterns of the family to understand whether a consistent structure exists and how it affects the individuals in the family at different levels. The findings revealed that both the sister and the mother presented consistent negation structures but differed from each other. Deniz could follow these patterns and adapted the negation gestures based on his interlocutor. However, he presented a limited ability to concatenate gesture units linearly compared to his mother and sister. These similarities and differences between family members and the role of input are discussed in line with the research questions and previous studies.
Ventral pallidum CaMKIIa neurons modulate affective behavior in wistar rats
The ventral pallidum (VP) is a basal forebrain nucleus composed of GABAergic, cholinergic, and glutamatergic neurons, playing a crucial role in processing both rewarding and aversive stimuli. Here, the pontetial affective role of CaMKIIa-expressing neurons in the VP was investigated by selectively inhibiting them using chemogenetics in Wistar rats. Inhibition of these neurons led to reduced locomotor activity and exploratory behavior in the open field test, elevated plus maze, and social approachavoidance test. The experimental group spent less time in the social interaction zone and exhibited increased anxiety-like behavior, as indicated by reduced open-arm exploration in the elevated plus maze. Depression-like behaviors, assessed by sucrose preference and forced swimming remained unchanged. In the novelty-suppressed feeding test, approach latency to food was similar between groups, while experimental animals took longer to begin eating in their home cage. During auditory fear conditioning, chemogenetic inhibition increased freezing, suggesting a heightened fear response. To characterize the neurochemical profile of CaMKIIa-expressing neurons in the VP, their co-expression with various molecular markers was examined. A small subset of CaMKIIa+ cells coexpressed parvalbumin, with fewer of them expressing calbindin, secretagogin, and choline acetyltransferase, highlighting the limited heterogeneity of this population. These results reveal the specific contributions of CaMKIIa-expressing putative glutamatergic neurons to the specialized role of VP in translating motivation into action.
Social and contextual modulation of ultrasonic distress vocalizations in wistar rats
Rats emit ultrasonic vocalizations when they perceive danger, but what they "say" and how often they "speak" may depend on how they perceive the immediacy of a perceived threat and who is around them. This thesis investigated how social context (presence of a same-sex conspecific during aversive experiences), sex (male or female), and the perceived threat intensity modulate 22 kHz ultrasonic distress vocalizations (USVs) of Wistar rats tested in increasing-intensity contextual fear conditioning, context tests, and acoustic startle tests. The results reveal that all three factors -sex, social context, and threat intensity- interact with one another to influence USV emission rates. Notably, pair-tested male rats exhibited a significantly higher amount of, and more sustained distress vocalizations compared to all other groups, particularly under high-threat conditions. The male dyads also displayed a significant increase in the principal frequency of their calls with repeated aversive stimuli during high context-shock contingency contextual fear conditioning and produced numerous overlapping, temporally coordinated calls. In contrast, single-tested females, despite initially vocalizing at similar levels to the other groups in low-intensity fear conditioning, remained completely silent in all subsequent tests. Pair-tested female rats emitted higher amounts of distress vocalizations compared to single females in higher-stress situations but still vocalized less than male pairs. These findings underscore that 22 kHz USVs are not static distress signals, but constitute communicative signals dynamically shaped by the animal's social environment, sex, and perceived threat level.
A computational approach to linguistic relativity with empirical experimentation
This thesis investigates linguistic relativity (LR), a hypothesis proposing that language influences thought, through a computational framework utilizing large language models (LLMs). To empirically test this proposition, the study prompt engineers LLMs as proxies simulating bilingual speakers, each representing a collective linguistic identity corresponding to one of 24 distinct native language groups, whose members are characterized by varying levels of English proficiency. Semantic embedding vectors are generated by eliciting adjective associations for nouns from various LLM configurations, thereby forming language specific conceptual representations. These embeddings are used to calculate semantic distances through measures of cosine similarity, whereby all of these language's conceptual representations are mapped to form a semantic field. Further experiments are conducted on these representational bilingual proxies to include both replications of existing studies in LR literature and novel cognitive tasks across a variety of domains, with results analyzed for systematic variations in task performance. The findings indicate that while native speakers of diverse languages employ distinct lexical choices to articulate conceptualizations of identical entities even in a common medium language (English), experimental data did not show statistically significant variations at the cognitive level of thought. Consequently, it is concluded that these cross-linguistic distinctions remain confined to the linguistic surface instead of extending to the deeper cognitive level of thought. Overall, by bridging the fields of linguistics and artificial intelligence, this study contributes to the ongoing investigation of LR within cognitive science studies by presenting a innovative and scalable methodological approach that addresses traditional limitations.
In search of language-based factors influencing rhythmic grouping
The Iambic-Trochaic Law (Hayes, 1995) was proposed as a universal mechanism governing rhythmic grouping. It predicts that sequences of sound events are grouped trochaically (strong-weak) when they alternate in intensity or pitch, and iambically (short-long) when they alternate in duration (Langus et al., 2016). Previous studies have found native language effects on grouping of both linguistic (Crowhurst & Teodocio Olivares, 2014; Langus et al., 2016) and non-linguistic (Iversen et al., 2008; Molnar et al., 2016) sounds, as they revealed grouping preferences incompatible with the predictions of the ITL. The present study investigated native language effects on rhythmic grouping by presenting native Turkish speakers sequences of tones (Experiment 1A and Experiment 1B) and syllables (Experiment 2). Lack of native language effects on grouping as revealed by the results, was explained by the stress 'deafness' (i. e., reduced sensitivity to stress deviations) exhibited by Turkish speakers, under the assumption that Turkish has predictable, fixed stress. That speakers of languages with fixed, lexically unmarked stress were reported to exhibit similar insensitivities to stress deviations (Dupoux et al., 1997; Peperkamp & Dupoux, 2002; Rahmani et al., 2015; Lu et al., 2018) supported this conclusion.
Inconsistency and multiplicity in the self
This thesis consists of an empirical study and a philosophical discussion. The empirical part is based on the Multiple Self-Aspect Framework whose fundamental principle argues that the self-concept is not unitary and it is composed of multiple self-aspects which reflect important components of one's personal life such as roles, social identities, relationships etc. Self-aspects are associated with attributes and when a self-aspect becomes activated via contextual inputs, its associated attributes become more accessible. The aim of the empirical study of this thesis was to investigate how one's perception change when two different self-aspects that are associated with opposing attributes become activated at the same time. Results showed that (1) simultaneous self-aspect activation rendered both opposing attributes and both self-aspects more accessible than baseline levels; (2) yet one opposing attribute still received more accessibility boost than the other, similarly one self-aspect became more accessible than the other. Philosophical implications of this empirical study along with the whole body of work derived from the Multiple Self-Aspect Framework are discussed subsequently: (1) in terms of how these philosophical implications relate to philosophical discussions of unity - multiplicity in the self, especially to Korsgaard's Constitution Model; (2) one of the crucial findings of the broad work related to the Multiple Self-Aspect Framework is that in general, people lack global traits. The implication of this finding is discussed in conjunction with the Situationism - Virtue Ethics debate.
Neural and cognitive underpinnings of trustworthiness in the prefrontal cortex via optical brain imaging
Human face has been considered to be an indicator of various attributes including attractiveness, calmness, and trustworthiness. Even a single look for a short duration might have an influence on one's attitude. This empirical study aimed to understand the neural correlates of trustworthiness judgments on face photos via an optic brain imaging (fNIRS) method. The experimental design has been developed to categorize the presented photos after watching them for 4000 milliseconds. The responses were collected within a 3-point Likert scale. The obtained findings indicate that there is a significant level of neural activation difference between positive and negative responses among a specific optode (Optode-3). Moreover, there are also significant levels of neural activation differences for the neutral responses versus others among 3 optodes (Optodes 12, 14, and 16). The results were also controlled regarding the saliency levels of the photos as well as the emotional states of the individuals in the photos via facial activation coding analysis. Overall results imply that trustworthiness level might be understood at a certain level.
Psycho-cognitive effects of the expectancy of score-based feedback in an activity involving artistic emotional expression
Feedback-based control is being used extensively in modern technology with great success to make systems behave in a desired manner. Also for human performers, receiving feedback about their performances provides opportunity to learn from their errors and deficiencies. However, with the wide-spread usage of performance improvement policies with score-based feedback, some adverse psycho-social effects started being reported. The purpose of this thesis is to design and implement an experiment for investigating how the "type" of performance feedback, i.e. whether the information is represented in a qualitative or quantitative manner, affects the human performer. For this study, an original task has been developed that involves artistic expression of emotions. The psychological correlates of the expected effects have been sought for via questionnaire-based methods, while their neural correlates have been investigated via seed-based functional connectivity analysis of fMRI recordings.
Morality-as-cooperation: How it relates to construal levels and how the theory could improve
This thesis is composed of two main parts. The first part involves an experimental study following Alper and Yilmaz (2020), who, informed by previous findings and construal level theory, hypothesized that experimentally evoking an abstract mindset would increase moral consistency and increase the valuation of individualizing moral foundations. However, their results did not support either of their hypotheses, adding to the mixed findings accumulated by previous research. I tested the same hypotheses as Alper and Yilmaz (2020) by using a more recent and sophisticated measure of morality based on morality-as-cooperation theory instead of moral foundations theory. However, the results again did not support the hypotheses. Additionally, I examined the possible influence of trait-level abstract-mindedness on the hypothesized effects. I failed to find any interaction effects other than that mindset manipulation increased the valuation of individualizing moral foundation only in the case of characteristically abstract-minded people. When combined, these findings indicate that the mindset manipulation may be overwhelmed by trait-level abstract/concrete mindedness, thus cannot influence moral attitudes. The second part comprises a critical assessment of morality-as-cooperation theory, which I employed in the experimental study. I attempted to show that the theory falls short of explaining certain aspects of human morality because it neglects the role of conformity to social norms. Then, I offer a theoretically grounded proposal supported by relevant empirical studies to improve the theory by integrating conformity as a moral foundation into morality-as-cooperation framework.
Effects of scaling shoulder width in VR on reachability and pass-through-ability affordances
Perceiving affordances, the action-possibilities of a system in an environment, is a survival key for the system (Gibson, 1966). Changing invariants for the system shapes its affordance perception (Warren & Whang, 1987). Pass-through-ability of an aperture, as a perceived affordance, is determined by the fit between the apparent aspects of the environment (e.g., perceived gap) and the perceived body scale. Changing body perception in real life depends on using tools such as a wheelchair or a long stick (Higuchi, Cinelli, Greig, & Patla, 2006; Higuchi, Cinelli, & Patla, 2009). Here, in order to understand the effects of body scaling on the affordance of pass-through-ability and reachability, we conducted a virtual reality and a simulation study. Participants were assigned to different virtual shoulder widths scaled to their real size (narrow, normal and wide). In the experiment, they were asked to walk naturally to pass through an aperture without colliding and reach a target on a table. The success rate of passing through an aperture and the speed were similar in all conditions, which implied that participants adapted their virtual bodies. We also showed that participants were closer to the target when assigned narrow compared to a normal-size shoulder, suggesting that participants thought their body became smaller, so they moved closer to the target. In order to control the adaptation for conditions, we also conducted a perceptual judgement experiment. Also reflected in the perceptual judgements, participants with narrow virtual shoulders thought that they had smaller shoulder width, an effect not observed in the wide shoulder condition, which together demonstrate an asymmetry in the effects of body scaling.
Belief dynamics and the role of epistemic peership in identity construction
The drive for social inclusion has been observed to impact both individual beliefs and their corresponding behaviors. An individual's uncertainty regarding their position within their affiliated groups has been identified as a factor contributing to the spread of conspiratorial ideation and extreme beliefs. The following paper introduces a model of belief dynamics adapted from predictive brain models which attempts to consolidate a broad range of existing psychology literature. It predicts that individuals will attempt to resolve perceived divergence from the beliefs of their affiliated groups by adjustments to their ideological positions. The model defines this as one strategy of uncertainty mitigation in social contexts. In three experiments, participants were asked to indicate their beliefs regarding a range of topics and the importance of those topics to their identities. Their responses were used to generate the illusion of a group of participants with similar beliefs. Participants were shown fabricated results indicating their divergence in opinion on one particular topic out of the range of topics and then given the opportunity to change their position on that topic. We found participants were more likely to change their endorsement of particular statements to reflect group opinion if they identified strongly with the beliefs used to generate the group. These results suggest that individual endorsements are influenced by others with whom they share a range of ideological positions.
Experience and insight under time pressure: A study with race game
In this paper, we experimentally study the effects of time constraints on learning efficient planning when subjects need to make sequential decisions. The subject is explored by utilizing a game theoretical tool called Race Game. In the context of race game efficient planning is achieved through backward induction which is considered to be a criteria that constitutes the ultimate rationality. Earlier studies demonstrated deviations from prescriptions of backward induction methodology, however more recent work demonstrated that subjects' convergence to backward induction reasoning. Based on those studies, we examine whether and how time constraints affect learning backward induction methodology. We explore these questions by investigating subjects' errors and response times in three different experimental time constraint conditions. The results indicate that time constraints, indeed, lead subjects to commit to more errors. Surprisingly, however, the solution process of subjects demonstrate a backwards order, resembling a convergence to using backward induction algorithm. The implications of this study may be beneficial for understanding how individuals learn effective planning and how deadlines should be set, for instance in the context of education and management
In search of a syntactic relationship between rhythm and language
Linguistic and musical syntax have been shown to rely on shared resources (Patel, 2003). In this study, we investigate the effect of an accompanying rhythm, another hierarchical domain, on sentence processing accuracy and speed. Two experiments were conducted to inspect the possible existence of shared processing of linguistic and rhythmic syntax. In the first experiment, sentences were manipulated to yield two levels of complexity: subject and object relative clauses. Rhythm was manipulated by using structured rhythms: sL, ssL, sssL, and sLL pulse sequences where "s" stands for a shorter inter-stimulus interval and L for a longer one. The s:L duration ratio was 1:2 (150ms:300ms). An isochronous (sssss..) control condition was also included. In the critical condition, the upbeat (s) that is heard right at the relative clause was presented 50 ms earlier. The dependent measure was participants' correct response rates and response times on the subsequent comprehension questions. The second experiment was identical to the first experiment with the exception that distorted rhythms were replaced with random beats to eliminate any structure in that condition. It was hypothesized that the rhythmic deviation in Experiment 1 would create competition of syntactical processing resources and hence decrease linguistic comprehension performance. In Experiment 2, we expected the random but not the structured rhythm condition to debilitate semantic processing of the sentences due to a complete "disconnectedness" between rhythmic and linguistic syntax. All the findings were null. There was no main effect of sentence and rhythm and interaction between the two in either of the experiments. This may indicate that rhythm and harmony rely on a different mechanism.
Ventral pallidal gabaerjik hücrelerin afektif ve bilişsel süreçlerdeki rolü
Basal ön beyin yapılarından olan ventral pallidum (VP) ve substantia innominatadaki (SI) GABAerjik hücreler akut ve kronik korkuyla ilişkili olan Amigdala ve Stria terminalis yatağı bölgelerine girdi sağlar. Bu çalışma VP ve SI beyin bölgelerindeki bu GABAerjik hücrelerin farklı davranışsal ve bilişsel süreçlerdeki rolünü ortaya koymak adına yürütülmüştür. Bu hücrelerin spesifik rollerini ortaya çıkarmak için, GAT1-Saporin toksinini ve %.9 derişime sahip salini yetişkin Wistar sıçanlarında stereotaksik ameliyat ile enjekte ettim. Ameliyat sonrası iyileşme için gerekli süreden sonra bu hayvanların zorunlu yüzme testi, açık alan testi, yükseltilmiş artı labirenti, Morris su testi ve Pavlovian korku koşullanması deneylerinde sergiledikleri davranışları gruplar arasında karşılaştırdım. VP ve SI GABAerjik hücreleri kalıcı olarak elimine edilen hayvanların davranışsal çaresizlik belirtisi olarak kabul edilen hareketsiz kalma sürelerinde azalma tespit ettik. Ayrıca bu azalma genel motor aktivitede bir azalma olmaksızın ortaya çıktı. Benzer şekilde, GAT1-Saporin grubundaki hayvanların korku koşullaması edinim gününde ve koşulamadan farklı bir bağlamda test edildiklerinde daha az donma tepkisi verdiklerini gözlemledim. VP ve SI bölgelerindeki GABAerjik hücrelerin susturulmasının anti-depresan etkisi olduğunu ve aktif baş etme stratejilerinin de kontrol grubuna kıyasla daha fazla olduğunu buldum. Bu anlamlı fark VP ve SI'daki amygdala'ya projeksiyon yapan kolinerjik hücreler üzerinde GABAerjik hücrelerin etkisiyle ortaya çıkıyor olabilir. Bu GABAerjik hücreler, klinik depresyon ve korku bozukluklarında yeni tip terapötik ilaçların geliştirilmesinde önemli bir rol oynayabilir.
Interactions of body representations in rubber hand illusion and tool-use paradigms
In neuropsychological literature, numerous case studies suggest two separate body representations in the brain; one for perception, called the body image, and one for action, called the body schema. Rubber hand illusion and tool-use paradigms have been used frequently to investigate these body representations, respectively. Although these experimental paradigms are thought to affect different body representations, interactions between them are inevitable, considering the common sensory modalities targeted by the techniques used for measuring their effects. Still, there has been minimal overlap between these related fields of study. In this thesis, we combined these paradigms in a novel experimental setup and comparatively examined the resulting changes in body representations. Specifically, after a tool-use task where subjects actively used a grabber tool with their right hand to move cubes close to or away from their body, we observed an increase in the metric representation of the right forearm length depending on the length of the tool used. Subsequently, the "tool-holding" rubber hand illusion also increased the forearm length representation if the subject saw a longer tool held by the rubber hand. Follow-up experiments showed that this effect in rubber hand illusion depends on prior active use of the tool, embodiment of the observed hand and tool, and a length disparity between the held and observed tools during RHI. Overall, these results reveal for the first time that the representation of forearm length, a component of body schema, can be modified through changes in body image.
Contribution of Ventral pallidal cholinergic neurons to behavioral despair and fear learning
Cholinergic neurons of the Ventral Pallidum (VP) densely innervate the Basolateral Complex (BLA) and Central Nucleus of Amygdala (CeA), and to a lesser extent project to the Bed Nucleus of the Stria Terminalis (BNST). Although basal forebrain cholinergic projections have been heavily studied in relation to cognition and explicit memory, there are very few studies that investigate the role of this neuromodulatory pathway in affective processes. The purpose of this thesis is to investigate the contribution of ventral pallidal cholinergic neurons to behavioral despair, anxiety, and fear learning. 192 IgG saporin, an immunotoxin selective to cells that contain p75 neurotrophin receptor, was bilaterally injected into the VP of eight adult male Wistar rats to eliminate cholinergic neurons. Lesioned animals were tested in the forced swim test (FST), open field test (OFT), elevated plus maze (EPM), Morris water maze (MWM) and Pavlovian fear conditioning. The results reveal that the elimination of VP cholinergic projections exhibit a reduction of behavioral despair, increased escape latency in MWM, and diminished freezing response in fear conditioning. These results indicate that elimination of VP cholinergic neurons have an antidepressant effect, while suppressing conditioned fear memory. VP cholinergic lesions also lead to deficits in hippocampus-dependent spatial learning. These results suggest that VP cholinergic neurons can be therapeutic targets in clinical depression and fear-related disorders.
A novel framework for morphological processing of Turkish
Morphological parsing is the computational task of breaking down words into their roots and affixes. There are several successful morphological parsers for Turkish, especially for inflectional morphology. However, there is a gap in the literature concerning the analysis of fusional properties of foreign-origin words, support for prefixes, and comprehensive derivational suffix coverage. To address this gap, this thesis describes and implements a new computational morphological processing framework for Turkish with novel principles. These principles are based on the recent opportunities and requirements in the natural language processing field, namely the transformer-based pre-trained large language models and fine-tuning approaches. The framework contains a description of language resources structure, a morphological analyzer that examines all possible parses of a word, a morphological disambiguator that picks the correct hypothesis among analyzer outputs, and error analysis modules for these tools.
Repetition in dementia: A study on Turkish
Objective: This study investigates the repetition performance of individuals with dementia on a repetition task. Method: The research examines the performance of 30 young adults, 32 senior adults (65+), and 32 individuals diagnosed with dementia on word and pseudoword repetition task. In addition to word repetition, this study also examines sentence repetition task constructed on a length-based scale with manipulations of complexity and reversibility in individuals with dementia. The task used in this study is divided into four main parts: the Mini-Mental State Examination to assess cognitive integrity; forward and backward digit span tests to assess working memory; the Turkish clinical adaptation of the Western Aphasia Battery's word repetition test; a pseudoword test, designed on the basis of the Turkish word repetition task list. Finally, a sentence repetition test constructed on a length-based scale, manipulating subject and object relative clauses and reversible/irreversible parameters. The research was conducted with young (18–64), senior (65+), and dementia-diagnosed participants. Results: Linear mixed modeling showed that semantic meaningfulness was important for correct word repetition in individuals with dementia (dementia group, meaningful word repetition coefficient = −8.119, p < .001, CI = [−11.602, −4.636]; nonword repetition coefficient = −0.300, p < .001, CI = [−0.413, −0.187]). In sentence repetition with relative clauses, object-relative clauses were observed to be more difficult than subject-relative and simple sentence repetition (subject-relative coefficient = −0.123, p = .005, CI = [−0.208, −0.038]; object-relative coefficient = −0.151, p = .001, [−0.236, −0.066]). For reversibility-based sentences, reversible sentences were more difficult (dementia group coefficient = −0.667, p < .001, CI = [−0.863, −0.471]). In addition, sentence- and word-length effects increased in direct proportion to the intactness of working memory. Conclusion: Participants diagnosed with dementia perform worse at pseudoword repetition task than word repetition. It is also demonstrated that participants perform worse at repetition of complex sentence structures than simple structures. While an intact working-memory helped with the repetition of longer words and sentences, and positively affected the repetition of subject and object-relative clauses, the impact was modest rather than significant. Similarly, for reversible sentences, a positive effect was noted, though it was not significant. Keywords: dementia, repetition task, semantics, syntax
Investigating the category effect in freely associated word responses and predicting free word associations using language models
The process of free association is key to human meaning-making, influencing both shared and individual understanding. Useful in many aspects, free association word resources are costly to make and attempts in computational modelling of free associations has yielded limited results only. Designed in two separate steps, current study first investigates whether sensory categories in the brain play a predictive role in the process of freely associating words. For this purpose, the data previously collected by De Deyne et al. (2018), namely Small World of Words (SWOW), was categorized by the aid of the pretrained Word2Vec model and analyzed. Secondly, the study tests whether a computational language model is able to capture the general regularities of freely associated human responses after being fine-tuned with relevant data. For this purpose, two language models, namely Tiny Llama and Google Gemma 3 were fine-tuned with SWOW data and the models were tested. Results show that there is a significant relation between the sensory areas in the brain and free word association responses and it is possible to say that fine-tuning significantly improves semantic understanding in free association responses in both models. However, values also highlight the limitations of both the base and fine-tuned models for handling such an open-ended task.
The influence of context structurization on attention dynamics and representational spaces in bert for question answering
Understanding how Large Language Models (LLMs) like BERT process and represent information is important for improving their abilities in tasks such as question answering. This thesis investigates how context structurization, a technique informed by cognitive principles of information organization, influences attention dynamics and representational spaces within bert-base-cased models. To support this investigation, a new dataset, 'SQuAD with Structurized Contexts' (SQSC), was created by applying a structurization method to original SQuAD contexts. The research compares three BERT model states: a pre-trained vanilla model (BERT-V), a model fine-tuned on unstructured SQSC contexts (BERT-UN), and one fine-tuned on structurized SQSC contexts (BERT-ST). Using an out-of-distribution (OOD) data sample generated for this study, experiments analyze these models' internal mechanisms when processing both unstructured and structurized versions of this OOD input. The study utilizes a range of quantitative analyses to compare attention distributions and hidden state representations across the different models and input conditions, employing measures of distributional divergence, vector similarity, and comparative representational geometry. This research aims to provide detailed insights into how structural modifications to input context affect BERT's internal processing. The findings are expected to contribute a better understanding of the relationship between input data structure and model mechanisms, offer the SQSC dataset as a new public resource, and inform future work in developing more understandable and effective language models.
Examining the complexities of decision-making:The connection of risk-taking, working memory, and second-language usage
This study aims to research whether individuals in a foreign language context make safer choices than when operating in their native language. In particular, we intended to analyze the impact of the framing effect, foreign language proficiency, and working memory on the behavior of decision-making. Prospect Theory was employed to measure the level of risk-taking during ambiguous decision-making situations (Asian Disease Problem) depending on the setting of reference points. Eighty-one participants took the English language proficiency test, working memory test, and decision-making tasks. The individual differences in language proficiency were related to reduced risk-taking when operating in the foreign language. A significant main effect of framing and a strong Language-Framing interaction were found; the framing effect was enhanced in Turkish and reduced in English. No main effect of language was found overall. The use of foreign language may alter the cognitive mechanism, although there is no general tendency for risk-aversive decisions. Research with larger and more balanced samples and neurocognitive methods is necessary to uncover the dynamics of decision-making context and its interaction with neural processing.
Müzikle uyarilan duygularda kendini referanslama süreçlerinin hemodinamik tepkileri ve interosepsiyon arasindaki korelasyonu
Interoception, an embodied emotion and cognition theory, refers to the tracking of bodily and mental states. Higher interoceptive awareness enhances emotion perception and affective intensity by relying on bodily signals. Closely related, self-referential processing integrates new perceptual input with prior knowledge through top-down and bottom-up mechanisms that align sensory information with internal models. Music, given its emotional and social nature, provides a highly embodied experience and can act as a proxy for a social agent, enabling listeners to infer intentions. When paired with interoception, music-evoked emotions offer a valuable framework for exploring individual differences in evaluative processes such as emotion processing. This study examined how interoception influences behavioral and neural responses during music-evoked emotions. Participants completed implicit and explicit interoception assessments, followed by music listening and emotion processing tasks. Behaviorally, emotion perception accuracy differed marginally across categories, without any effect of interoceptive awareness. In contrast, functional near-infrared spectroscopy (fNIRS) revealed trend-level and group-specific hemodynamic differences in prefrontal subregions, with several channels modulated by interoception. Overall, the findings suggest that interoceptive awareness slightly modulated neural engagement during emotional evaluation. Despite modest effects, the results point to a potential link with embodiment, emphasizing the roles of interoception and self-referential processing in music-evoked emotions.
The role of awe on self-referential processing: AN EEG oscillation study
This study aimed to investigate the effects of awe on self-referential processing (SRP) at the electrophysiological level. Participants were exposed to awe-inducing or neutral video clips, followed by semantic, somatic, attention, and meditation tasks. EEG was recorded throughout the experiment to analyze peak frequency and peak magnitude in the alpha (8-13 Hz) and theta (4-7 Hz) bands. Additionally, heart rate (ECG) was measured to validate the successful induction of awe. Thirty-one healthy adults viewed three awe-inducing and three neutral videos, each followed by the corresponding tasks. Participants also completed the Self-Size Scale before and after each block to report perceived changes in self-representation. Results showed no significant differences in perceived self-size, heart rate, or subjective ratings of attention and pleasantness between awe and control conditions. EEG analyses revealed robust regional and hemispheric patterns in alpha and theta activity; however, these reflected general task engagement rather than awe-specific modulation. Likewise, grouping participants into "Smaller Self," "No Change," and "Bigger Self" categories did not yield significant differences in neural measures. These findings highlight the methodological challenges of reliably eliciting awe in laboratory settings using video-based induction. Factors such as stimulus duration, repetition, and reduced ecological validity may have limited the strength of the awe experience. Nevertheless, the study provides a comprehensive paradigm integrating EEG with validation via ECG, underscoring the complexities of awe research. Its contribution lies in offering an interdisciplinary perspective on self-referential processing and establishing a methodological foundation for future research.
Syntactic processing differences and the effects of memory-load interference for object relative and subject relative clauses in Turkish
The purpose of the study, which focuses on the relative clauses in Turkish, is twofold: In Experiment 1, it was aimed to fill the gap in Turkish literature with regard to syntactic complexity difference between subject relative clauses and object relative clauses. As a self-paced reading experiment, participants read either subject relative clause of object relative clause to measure the processing cost as a slowing down in reading. The result of Experiment 1 revealed that object relative clauses are harder to process than subject relative clauses suggesting that there is a subject preference in Turkish. Secondly, as a separate but related follow-up study, it was tested whether such complexity interacts with memory load in any way. For this purpose, participants memorized a set of words while reading syntactically complex sentences and syntactically simpler sentences (object and subject relative clauses, respectively). The study also manipulated whether the memory load items and the words in the sentence were similar or not (matched or unmatched conditions). Performance in recall was significantly higher for the unmatched condition than the matched condition. Recall was also higher in simpler sentences than complex sentences. Results of Experiment 2 indicated that syntactic processing is not modular meaning that both linguistic and non-linguistic verbal processings share the same verbal working memory resource. Moreover, online and offline measurements of both studies are compared to show why offline studies are different in nature and why online studies are more reliable as long as sentence processing is concerned.
Effects of Amygdala lesions on social behavior in rats
Despite its importance mechanisms of prosociality are still not well known. In the literature, helping behaviour of rats to a restrained rat is becoming a tool for assesing this topic. Helping behavior is closely associated with sensitivity to another one's distress, and amygdala plays an important role in this sensitivity. The present study investigated whether bilateral amygdala lesion would affect rats' decision making to help when their cage-mate was restrained. Adult Wistar rats were subjected to a role reversal acquisition where they acquired the behavior of opening the door of the restrainer in which one of their cagemates was captive. Then, they were divided in three groups; naive, sham operated (Sham) and basolateral amygdala lessioned (Lesion). The rats were tested in an open field with three restrainers (empty, with a Sham or Lesion, with a Naive). The door opening and side preferences of rats were measured. In the control test there was a naive in the formerly empty restrainer, and the other two restrainers were empty which they formerly were not. No significant differences were found among the groups with respect to door opening and side preferences in both the main and the control tests. Door opening and to be close to the empty restrainer preferences were lowest in the main test and highest in the control test. The lower interest in the restrainer with a cagemate during the control test indicates that, the dominant door opening behaviour drive was not helping but was probably habit formation.
An investigation of false memory in Turkish-English bilinguals-
False recognition across languages is investigated using the Deese-Roediger-McDermott (DRM) paradigm. English-Turkish balanced bilinguals studied word lists which are associates of a critical lure. Some lists were received by the participants in English while others in Turkish. After the study phase, participants performed a recognition test that included studied words, nonstudied critical lures, and nonstudied new items whose language were either the same with or different from those used in the study phase. Half of the participants were instructed to recognize only if the test word was in the same language as the studied word while the remaining received no such instruction. The results demonstrated a strong false memory effect for both within-language and across-language conditions. False recognition decreased when the study and test languages differed compared to when they were the same, and this effect was similar for both groups which had an instruction and no instruction. These results were interpreted in such a way that even though false memories can occur across different languages, they are not completely independent from the language assuming that the participants encode not only the meaning of the words but also the language of the words (i.e., the phonological form of a word in that particular language) that they were presented during the study phase, so that they were encoded as distinct and presented less false alarms. In terms of bilingual language representation, the results are consistent with models that assume a separate lexical representation for each language and yet a common single conceptual representation for both languages.
The role of expectation in change blindness
Human may believe that they notice every important change in their environment. However, the phenomenon of change blindness – a failure to notice salient changes to our visual world – tells a different story. The present research investigated the role of expectation in change blindness by using a modified version of the flicker paradigm. The sample consisted of 120 university students (60 females and 60 males) aged between 18-26. The study used two stimuli, ball and clock, which had an original and a changed version. The changes in the images were either in the expected direction with the minute hand of the clock moving clockwise and the ball sliding down or in the unexpected direction. Response times for the detection of change were collected. It was hypothesized that response time (RT) for expected changes would be lower than RT for unexpected changes. The overall results of the experiment with the two stimuli combined showed that participants were able to detect expected changes faster than unexpected ones, supporting our hypothesis. When the two stimuli were investigated separately, participants were able to detect expected changes faster than unexpected changes for the ball, while the difference between the two conditions was non-significant for the clock. The findings are discussed within the framework of expectation-based theories.
Consciousness and implicit memory trace for the unexpected stimulus in inattentional blindness
Inattentional blindness (IB) demonstrates that an unexpected stimulus (US) may be undetected when attention is engaged in a task. Previous studies using direct memory measurements relying on verbal report failed to find a memory trace for the US. Block (2011) suggested that contrary to Access Consciousness, Phenomenal Consciousness can exist without verbal report and attention. Mack and Rock (1998) found perceptual and semantic priming effects for the undetected US by using indirect memory tests. However, there are no items to be ignored in their paradigm. The present study aimed to show that the undetected US in an IB paradigm involving items to be ignored is processed and produces priming effects at the perceptual and semantic level. In Experiment 1, participants who were blind to the unexpected word were more likely to complete a single-solution word fragment with the US than the participants who were not exposed to the word. In Experiment 2, inattentionally blind participants were more likely to choose the picture for the unexpected word than the ones who were not exposed to the word. These two studies replicated previous findings in a paradigm with ignored items. The results showed that the undetected US is presumably processed at a phenomenally conscious level and produces perceptual and semantic priming effects on a subsequent task. The findings are also consistent with studies showing neural activations in the brain for the undetected US. The findings have implications for possible memory correlates of undetected visual information and for theoretical propositions regarding consciousness. Keywords: Inattentional blindness, priming, consciousness, word fragment completion, picture choice
Motion perception in multiclustered environments
The ability to recognise objects in the environment is a fundamental process for all living beings. The features of the objects (size, color, location, etc) in addition to their integration with the environment play a significant role in identifying the object. Despite the extensive evidence in psychology and neuropsychology, the exact contribution for various features to recognition is still inconclusive. Although it is an easy task for the brain to identify an object, it remains difficult to identify an object in a crowded scene – a perceptual phenomenon where having similar flankers around a target object decreases the visual acuity of the target. The more the objects are similar to each other, the more difficult it is to identify the target object. In this thesis, we focused on studying the effect of global and local features in a crowded scene of multiple clusters on detecting the target object. To achieve this, similar stimulus metrics (e.g. density, distance, size) are calculated globally for the entire scene and locally for the target object and/or cluster. We found a global effect of the density metrics (e.g. the number of clusters) on performance. We also found a significant effect on global and local aspects of eccentricity and size metrics. Keywords: Motion Perception , Ensemble Perception, Attention
Duration of stability differences for words and pseudowords in the verbal transformation effect
Verbal transformation effect (VTE) refers to the phenomenon in which listening to the same word presented repeatedly leads to multiple interpretations (e.g. 'life life life...' becomes 'fly fly fly...'). Although there are several psychological models trying to account for VTE, the underlying neural mechanisms are largely unknown. Short-term synaptic depression (STD) is a related biophysical mechanism in that constant stimulation of a pre-synaptic neuron reduces the probability of a post-synaptic neuron firing due to neurotransmitter depletion. In addition, the rate of depression depends on whether the action potential activity between pre- and post-synaptic neurons is paired (paired activity results in a faster depression rate). We used 18 Turkish stem words and pseudowords as examples of paired and unpaired AP activity, respectively, in a standard VTE experiment paradigm and found that words remained stable approximately 400 ms shorter on average compared to pseudowords. This difference in stability durations may be due to faster depression of synapses in networks processing words, which suggests that STD could be considered as a suitable neural mechanism for VTE.
An erp study of the processing of subject and objectrelative clauses in Turkish
The first aim of this study is to determine which type of relative clauses – subject relative clauses or object relative clauses – are easier to process. The second aim, assuming that there will be a difference between subject relative clauses (SRC) and object relative clauses (ORC) in terms of the processing difficulty, is to reveal on which words or word groups in the sentence the difficulty presents itself. In an Event-Related Brain Potentials (ERP) experiment, participants were given a total of 240 sentences, where 120 had SRCs in them (60 of which were in the grammatical function-subject, "[The senator who applauded the PM] scolded the minister"), and the other 60 were in the grammatical function-object,"The minister scolded [the senator who applauded the PM"]); the remaining 120 sentences had ORCs (again, 60 of which were in the grammatical function-subject, "[The senator that the PM applauded] scolded the minister," and the other 60 were in the grammatical function-object, "The minister scolded [the senator that the PM applauded])." The following factors were used in the statistical analysis: Grammatical Function (GF) (subject, object) x Clause Type (SRC, ORC) x A(nterior)-P(osterior) distribution (frontal, parietal) x LAT(eralization) (left, right). Behavioral findings revealed that participants perform better when SRCs are in the subject function and ORCs are in the object function. In ERP findings, the results of the experiment revealed that subject relative clauses are easier to process than object relative clauses in the subject function. Therefore, object relative clauses revealed Left Anterior Negativity. The second result is the cognitive difficulty observed on the head noun of the relative clauses. In this study, relative clauses were investigated for the first time by using the ERP technique. Key words: Language Processing, Event-Related Brain Potentials, Relative Clauses, LAN
The effect of transcranial direct current stimulation on syntactic processing in aphasia
There are studies that investigated the effects of tDCS on linguistic abilities both in healthy and aphasic individuals. tDCS studies in aphasic individuals revealed positive effects on linguistic abilities based on the cerebral area of stimulation and conditions. The aim of the current study was to evaluate the effect of tDCS on syntactic processing by activating or supressing Wernicke's area in anodal and cathodal conditions. 10 individuals with aphasia participated in the study. All aphasic indiviuals were administered the Test of Language Assessment in Aphasia. In the beginning of each session we applied our linguistic task via a computer program that consisted of 20 target sentences, which were formed of four different syntactic structures with varying complexities. This task measured the true/false scores, reaction times, and the distractor use by aphasic individuals. After the linguistic task, each participant was subjected to 2mA tDCS for 20 minutes. In the anodal condition we applied tDCS on the left Wernicke's area (CP5), while in the cathodal stimulation we applied tDCS on right the homologue area for Wernicke (CP6). Immediately after the tDCS session, participants were subjected to the linguistic task once again. Five consecutive sessions were conducted in a period of one week. The results of the study revealed that Anodal-tDCS may improve language skills by decreasing bilateral activation whereas Cathodal-tDCS was ineffective on syntactic processing and had a negative effect on certain syntactic structures. Key words: Syntactic processing, aphasia, tDCS, neurolinguistics, language disorder
Recognition of sequential harmonic and inharmonic sound sequences investigated by behavioral and electrophysiological studies
Consonance rating when listening to the two consecutive or simultaneously presented sounds is associated with the ratio of their fundamental frequencies. The simpler ratio is perceived as more consonant. In this thesis, two melodies that consist of the same 10 tones were generated. Melodies had the same contour but differed with the order of tones so formed different harmonic relations between consecutive tones. Non musician participants were asked to choose which melody (harmonic or inharmonic tone sequences) was more consonant and the rating for each melody was not significantly different than each other. However, it was easier for them to notice the same amount of frequency change that occurs in one note of the harmonic sound sequence. Results suggest that better performance of the recognition task for harmonic sequence is related to better encoding and building a higher level expectation due to harmonic relations of sounds. An EEG experiment was conducted to test memory load hypothesis. The sustained anterior negativity (SAN) and power of alpha/beta oscillations were compared as a measure of working memory load. Amplitude of SAN did not reveal a difference in working memory load. However, beta and low gamma power was lower for harmonic sequences in the frontal cortex at the end of the stimulus presentation which suggests a more stable memory trace for harmonic sequences. Nonmatch stimulus elicited a P3b signal with higher amplitude for harmonic condition. This result suggests that a higher level expectation occurs for harmonic condition as all the other parameters that affect P3 signal were well controlled in the experiment.
The underlying cause of the framing effect: A dual process approach
A switch of preference is often observed in identical questions, depending on how the choices are framed. This phenomenon is called the framing effect and it displays a violation of the rational choice theory and provides support for dual process theory accounts. Many dual process accounts indicate that; an emotional System 1 is the underlying cause of the framing effect however there are counter arguments that support the idea that; an analytic and working memory dependent System 2 is the underlying cause. Working memory dependence of System 2 is regarded as the main differentiator between the two systems. Thus in this research, a concurrent digit span backwards (DSB) task was given to suppress System 2, with risky choice framing type questions. It was hypothesised that, framing effect can be the result of an irrational emotional reaction to the positive and negative words that describe the choices thus the underlying cause might have been attributed to System 1. As a result, under a suppressed System 2 the amount of framing effects would increase. However findings showed that there was no significant effect of the memory load and counter to the expectation, in the memory load condition the number of framing effects were reduced. This result supports the argument that the underlying cause of the framing effect is System 2 , which means that context effects increase with analytical thinking. Thus this research signifies the importance of emotions and System 1 processes in leading to rational choices.
Machine learning and EEG in epilepsy
Purpose: This study investigates the ability of deep learning to improve epilepsy diagnosis. Without pathology diagnosis involves long and costly EEG monitoring. To achieve faster diagnosis, researchers used graph theoretical metrics from brain connectivity networks. However, diagnosis by deep learning, directly on connectivity data, was not yet studied. Methods: A convolutional neural network (CNN) algorithm was applied on directed Granger causality (GC) connectivity measures, which were derived from 50 seconds of interictal resting-state surface EEG recordings from a group of 30 subjects with epilepsy and a 30 subject control group. The same EEG data was also used to train a long-short-term-memory (LSTM). Performance was determined with a k-fold cross validation approach. Results: Largest connectivity reductions occurred in frontal regions in the delta band, and largest increase occurred in the gamma band for left lateralized connectivity from frontal to posterior regions. The CNN achieved highest accuracy (82%) with directed GC matrices that included delta and gamma frequency bands, using the FP1, F3 and P3 electrodes. Notably, the LSTM achieved highest accuracy (70%) on the same electrodes. Other electrode combinations only showed significant accuracies with differently normalized GC data. A high accuracy of 90% (F1-score 90%) was achieved by fusing the CNN predictions that resulted from the three best performing data preparation methods. Conclusions: A generic CNN algorithm is able to detect epileptic features from GC matrices, provided that the data is prepared appropriately. To exploit multiple epileptic features, different predictions can be fused into a hybrid classifier. Recommendations: The high accuracy achieved in this study shows that this approach could prove a valuable aid for clinicians.
An investigation of differences between visual and auditory memory
The main aim of this study was to examine the differences between auditory and visual memory and to investigate the encoding strategies during the recall of the unfamiliar Chinese words that was presented briefly, both visually (written word) and aurally (spoken word). Furthermore, primacy and recency effect were investigated and each stimuli was analyzed in accordance with the visual and auditory scores. The experiment took place in the psychology laboratory and 88 university students between the ages of 19-25 were selected for the experiment. The trial consisted of three parts. The first part was the learning phase. Learning phase of the trial process required participants to attend combination of visual and auditory modalities by visually monitoring the Chinese words' representations in picture format, together with textually displayed related Chinese word, and aurally, by hearing the same Chinese words in audio format. Participants were then tested with regard to their recall ability of the Chinese words in both modalities. During the auditory and visual tests in the second and third parts of the trial, the Chinese words that were presented in the first part were given one by one as a cue in mixed order without images, and the participants were instructed to write down the Turkish meaning of the words they recalled in the answer form. In the auditory test section, the auditory cue words were repeated five times over a period of time (13400 ms) as it was in the first section and participants only heard the Chinese words. Also, in the visual section, the words remained on the screen for the same period of time (13400 ms) as shown in the first part and participants only saw the Chinese cue words on the screen without any accompanying spoken word. In both test parts, all the words were identical to what they exposed in the learning phase. In order to randomize and eliminate possible differences, half of the participants were given the auditory test first and then the visual test; the other half first started with the visual test and then the auditory test. Immediately after being tested, participants were asked to describe the recall strategy they used to remember the words through a short questionnaire and all the results were analyzed. Individual differences in visual and auditory encoding strategies and their effect on recall performance were also investigated. In conclusion, the findings of this research were as follows: although it was observed that the number of correct recall in the auditory test was higher than those in the visual test, there was no statistically significant difference in between auditory and visual memory performances, the recall rates of visual and auditory information did not differ significantly by gender, in comparison of individual differences in visual and auditory recall scores, individuals whose auditory memory performance is superior to visual were predominant, primacy effect was superior in the recall rate of visual items and recency effect were superior in the recall rate of auditory items. Nonetheless, primacy effect was found as effective as recency effect in the recall of the auditory information. Furthermore, participants who used the "associated them with some other words" strategy achieved the highest level of auditory recall performance. On the other hand, "matched the Chinese characters with fruit images" strategy provided the highest level of visual recall performance to the participants. All of the results supported our hypotheses except the first and the last finding. Keywords: auditory memory, visual memory, modality effect, recall, primacy effect, recency effect, encoding strategies
Multisensory integration through auditory and somatosensory mismatch negativity
In everyday life, we rely on our sensory organs to gather information from the environment to take evolutionarily necessary actions. The most crucial of these information comes from the novelty in the stimulus we face. While a pattern of the same sensory cue repeats, it usually does not pose a danger to the self. However, a change in this pattern could mean a novelty in the environment that is needed to be processed to gain enough information about this new situation. In this aspect, mammal brains have a unique mechanism of mismatch responses which are elicited after a certain deviancy appears in the pattern of the stimuli. These responses have been observed with electroencephalography (EEG) in auditory, somatosensory and visual modalities as mismatch negativity (MMN). However, the effect of multisensory integration has not been studied in audiotactile mismatch responses. In this study, I examined the audiotactile novelty detection mechanisms using EEG. I found that, in the presence of auditory deviance, mismatch negativity (MMN) usually is within the auditory MMN range. Also, in presence of auditory standard stimuli, somatosensory mismatch negativity tends to be at the more negative side resembling its auditory counterpart.
The effect of parametric physical attributes of 2d shapes on shape recall and on classifiying shapes as natural or unnatural
Previous research in the visual perception domain has shown the interaction between some attributes of shapes and how humans perceive them differently when those attributes are changing. However we felt there are not enough resources in the literature regarding the geometrical parameters of 2D shapes. Also about the naturalness classification in visual perception, there are studies focusing on the natural scenes but again, the knowledge of the naturalness perception according to the 2D geometrical shape parameters is pretty limited. In this study we aimed at combining these two subdomains and providing quantitative findings about how the geometrical parameters like edge count, concavity, naturalness and uniformity are affecting the memory performance and naturalness classification for a shape. We designed a behavioural experiment to test different shapes with different values of those parameters and presented these shapes to participants in a recall task and a naturalness survey. Then we ran some correlation analysis between those values and memory performance and naturalness rating. We found out that edge count and concavity significantly affects the memory performance for a shape. Another finding was that our judgement of a shape being natural or artificial is affected by the edge count, concavity level and roundness level of a shape. Lastly, we observed that the memory performance is worse for the shapes that are rated as natural.
Behavioral correlates of perceptual confidence in a motion tracking paradigm
Perceiving motion of objects around the environment requires understanding of several features of motion such as direction, speed, and density. In this process, we rely both on the sensory input and our confidence level regarding our decision about the features of motion. However, the signal reaching our senses is not always entirely intact hence it includes noise. In this context, signal-to-noise ratio affects both motion detection and perceptual confidence. In this study, I examined the effect of signal-to-noise ratio on motion detection accuracy and perceptual confidence with the Continuous Perceptual Task Paradigm (CPR). Participants were asked to hit a target with a joystick that randomly appeared on the outer diameter of a circular random dot cinematogram (RDC). In addition, individuals were prepared for the main experiment by applying the Reaction Time (RT) task and 4 Alternative Forced Choice (4AFC) tasks before the main experiment. I found out that radial joystick accuracy increased with increasing signal-to-noise ratio. Also, joystick strain increased with increasing signal-to-noise ratio. These results indicate that perceptual confidence and motion detection accuracy rely on the availability of the information about the direction of motion.
Meditasyonun, bir duygu düzenleme stratejisi olan kopma (detachment) üzerindeki etkisi
Meditation is a highly practiced technique to create emotional balance, cognitive enhancement, and general well-being. The aim of this study is to investigate the benefits of meditation on attentional stability and emotion regulation. We created a psychophysics task consist of number counting Stroop task and played emotionally triggering sounds on the headphones during the experiment. We intended to create cognitive load by asking the participants to respond to the tasks by congruent or incongruent according to the condition of the visuals in 1 second, while the affective sounds would distract their attention. The study consisted of 8 conditions as the combination of 2 visual conditions (congruent and incongruent) and 4 auditory conditions (arousal high- arousal low- pleasure high- pleasure low). We expected the group consisted of meditation practitioners to respond with higher accuracy rate (percentage) in lower reaction time (ms) compared to the meditation naïve control group. During the experiment, we recorded the electrophysiological activations of the participants and expected lower beta and gamma oscillations in the meditation group's frontal and temporal regions. The behavioral results fulfilled our expectations since the meditation group performed with higher accuracy rate and lower reaction time. Although the analysis of behavioral results showed that congruency had significant effect, there were no effect of affective sounds on participants' accuracy rate and reaction time. On the other hand, electrophysiological results revealed that both the congruency and sound type affected the participants', and in group comparison, the meditation group generated lower gamma oscillations both in frontal region which is associated with cognitive control and temporal region where the emotion processing occur. Our results indicated that meditation provides higher attentional stability and increase emotion regulation skills especially in neural level.
The effect of harmonic and inharmonic sound on roughness perception in the tongue and fingertip
Multisensory integration refers to the integration of multiple senses by the nervous system. Auditory and tactile features are closely related senses as can be understood from the fact that adjectives such as soft, rough, and warm are used commonly for auditory and tactile features. Previous studies show that different characteristics of auditory cues may cause perceiving tactile cues as smoother or rougher. In this thesis, the effect of harmonic and inharmonic sounds on tactile roughness perception was studied by tongue and fingertip while they are presented simultaneously. We expected the participants to perceive surfaces rougher while they listen to inharmonic sounds due to auditory roughness. We presented simultaneous and sequential harmonic and inharmonic sounds with three sandpapers with different roughness levels (P100, P120, P150 grit numbers) to the participants. Results suggest that participants perceive sandpaper with the P120 grit number rougher while they listen to simultaneous inharmonic sounds than simultaneous harmonic sounds by their fingertip in two different experiments. However, any effect of harmonicity on the sandpapers with P100 and P150 grit numbers was not observed for fingertip. In addition to this, there is no effect of harmonic and inharmonic sounds on roughness perception for tongue. We suggest that auditory roughness may enhance tactile roughness perception for surfaces with particular roughness levels for fingertip, possibly when there is an ambiguity in roughness estimation.
Investigating the role of position and orientation in shape perception using visual crowding and contour integration
The deterioration or reduction of the perception of the target due to the nearby objects is called the visual crowding effect. Crowding can occur as a result of similarity and proximity. These two conditions also result in contour perception with high congruency between the elements. Contour perception is the unitary perception of congruent individual items. Although many physical aspects can result in crowding and contour perception, congruencies of orientation and position are the two primary indicators. In this experiment, four positional configurations, namely left-circle, right-circle, left-diagonal and right-diagonal, of the target and flankers were used. According to these positional configurations, congruent and incongruent orientations were created. We hypothesized that crowding and contour should have an exhibitory effect on each other. In the previous studies, target and contour objects were separated from each other. In this study, the target was also a part of the contour pattern. This allowed us to observe the interaction of crowding and contour in the same arrangement. The task was a simple orientation discrimination task between two targets. Another hypothesis was that low-level shapes' contour perception should occur even with three objects in the scene. The accuracy rates (percentage) and reaction times (ms) were compared as outcome variables. The results indicated that contour and crowding are two concepts that cannot co-exist based on the accuracy results. Also, the analysis of the accuracy rates confirmed that the three objects were enough to create simple linear shapes but not circular shapes.
Preferences, timing, and limitations during reasoning: A dual process approach
How are reasoning processes shaped by the heuristic system and analytic system? In the present study, we were focused on how heuristics and analytical thinking affect reasoning. According to dual-process theories, reasoning consists of two distinct modes of processing: System 1 and System 2. System 1 generates responses that are automatic, fast, and intuitive. This system does not need working memory resources. The other system is reflective. Characteristics of this system are deliberative, slow, and conscious. System 2 depends on working memory capacity. Therefore, system 2 needs working memory resources. In the present study, the experimental design was as follows: All participants performed randomly distributed modified version of the bat and ball problems and the syllogistic reasoning problems while they kept memory load in mind and had a time limit in the initial response stage. Then the questions were asked again without memory load and deadline. Both tasks consist of conflict (experiment questions) and no-conflict (control questions) questions. Whereas participants chose among four options in a modified version of the bat and ball problems, they chose between yes and no, considering two premises and a conclusion in the syllogistic reasoning problems. A two-response paradigm was applied. The problems were asked twice. In the first presentation of the problems, we occupied the participant's working memory with a dual task procedure and time pressure. We replicated the common implication of system 1 with fast response and system 2 with slow thinking.