19
Archived Theses
0
DOIs Assigned
0%
DOI Rate
Discipline
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.
2 boyutlu şekillerin fiziksel özelliklerinin şekil algısına etkileri
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.
Akıl yürütme sırasındaki tercihler, zamanlama ve sınırlamalar: İkili süreç yaklaşımı
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.
Examining the role of eye movements in facial expression and emotional intensity recognition via machine learning
Recognition and classification of emotional face expressions is one of the most advanced abilities of humans. Many studies have investigated recognition processes and scanning strategies for different facial expressions but there is still no consensus on a particular scanning pattern for emotion types. Most of the previous studies also did not include the level of emotional intensity of facial expressions. The aim of this study is to investigate which eye movement parameters are important for emotional expression recognition and emotional intensity recognition processes. Eye movements provide important clues about face scanning strategies. Therefore, we examined the eye movements of 60 participants and fed machine learning models with eye tracking data. Neutral, surprised, sad, happy, and fearful facial expressions were presented to the participants with 0%, 25%, %50, %75, and %100 emotional intensity. Half of the participants were asked to classify the emotion type and half of them were asked to rate the intensity level of the emotion. Total number of fixations, pupil size and number of fixations on areas of interest (AOIs: eyes, nose and mouth) were collected for eye tracking analysis. Results showed that the fixation number on facial expressions decreased as the intensity of the expression increased. It was also found that participants fixated most to the eyes and least to the mouth regardless of the task. There was no difference between fixation numbers to eyes and nose during intensity recognition tasks for all emotion types. However, the fixation number towards the eye, nose and mouth differed between emotion types during the emotion recognition task. Higher emotional intensity resulted in less fixations in the mouth area. Analysis of pupillary response showed that fearful faces resulted in larger pupil size compared to all other expressions during the emotion recognition task but this difference was not evident during the intensity recognition task. Data collected from the eye tracking device has also been implemented in Random Forest (RF), Decision Tree and k-Nearest Neighbors (k-NN) models. All models achieved an accuracy rate at above chance level for both emotion classification and intensity classification. The highest accuracy rate was achieved with the RF method. The model was able to classify emotion types with an average accuracy of 85.8% for emotion recognition task and with an average accuracy of 89.2% for intensity recognition task when implemented with fixation point of gaze, fixation duration and pupil size. Emotion and intensity classification remained similar for the intensity recognition task with the same parameters. Effect of task, emotion type and intensity level were observed for pupil size and fixation numbers in the eye tracking analysis. However, the task did not affect the classification performance of the model. Also, intensity level of expressions or emotion type of an intensity level did not affect machine's performance as well. We interpreted these results as scanning strategies implemented by viewers while reading emotional expressions with different intensities. Results of the current study further discussed possible application areas.
İmajdan müziğe: İmaj altyazısı ile çapraz modlu melodi üretimi
Advances in machine learning in recent years have also been seen in computationally creative systems. Interest in machine-generated artifacts paved a way for creative models to evolve as such. But the earlier methods mostly explored a one-domain approach and cross-modal learning has stayed relatively unexplored. Thus, the direct mapping between modalities for cross-modal creative models is not fully explored. This work proposes a novel methodology for generating symbolic music through images by directly mapping their features. A CNN encoder and deep-stacked LSTM decoder are the base models as the proposed method uses the image captioning approach to map the two domains' features. The generated music is evaluated quantitatively by using a custom genre classification model and BLEU scores calculations. The qualitative evaluation involves a melody listening test with human evaluators. The results show that the proposed method works well for music generation.
Psikoz-benzeri deneyimleri olan kişilerde bilişsel yanlılıklar ve sosyal biliş: Sonuca atlama ve yanlışlayan bilgiye önyargı yanlılıkları sosyal yargıya varma süreçlerinde rol oynamakta mıdır?
Cognitive biases such as Jumping to Conclusions (JTC) and Bias Against Disconfirmatory Evidence (BADE) have been implicated in the delusion formation and maintenance. In line with the continuum approaches to psychosis, such biases have been observed not just in clinical populations but also in otherwise healthy individuals with psychotic-like experiences. Current study aimed to assess JTC and BADE biases in a community sample with a novel paradigm. The results of the current study showed that a tendency to arrive hasty decisions and belief inflexibility in the face of new information might be present in people with psychosis proneness in their daily interactions.
Toplum boyutunun kurucu dizilimi üzerindeki etkisi: Gelişmekte olan işaret dilleri ile yerleşik işaret dillerinin karşılaştırılması
The current study examines the effect of community size on constituent order by comparing conventionalized sign languages (TID and LIBRAS) and emerging sing languages (CTSL and CENA) from two different countries. When the relevant literature is examined, it is observed that languages that emerge in communities with larger populations tend to have a more uniform structure, while languages that emerge in smaller and closed-knit communities exhibit greater diversity regarding their constituent order. Data was collected through an elicitation task comprised of 30 video short video clips containing sentences with intransitive, transitive (reversible vs. irreversible events), and ditransitive structures. Significant relationships were found between community size and constituent order, revealing that conventionalized sign languages presented more uniform word orders in intransitive and ditransitive structures and transitive structures with irreversible events, whereas no significant relationship was detected for reversible events. The study contributes to the existing literature by demonstrating that languages from larger communities rely on commonly used constituent orders to describe events; in contrast, languages from smaller communities produce more uncommon constituent orders. The current study has practical implications for the relationship between sign languages in different stages of development and constituent order preferences, highlighting the developmental phases of language emergence and evolution.
Doğal dildeki bilişsel eğilimlerin evrenselliği üzerine:İsim öbekleri iç dizilim örneği
The present study experimentally investigates the order of NP-internal modifiers in gesture modality as practiced by Turkish speaking participants in an attempt to understand the natural order within NPs crosslinguistically, whether the participants' preferences reflect a homomorphism bias, and whether their preferences are influenced by their native language. For these purposes, Turkish-speaking participants (N=44) randomly assigned to two conditions where access to their native language was suppressed in the first block (suppression-first condition) or where access to their native language was suppressed in the second block (no-suppression-first condition). Under both conditions, the participants were asked to improvise gestures to describe visauls showing geometric shape clusters varying in distance, number and features. Results of the experiment indicate that the majority of gesture strings produced by Turkish speaking participants is homomorphic and the mostly preferred NP internal order is Dem
Examining the effects of interoceptive awareness and self-focus on emotion perception from point-light dance movements: An eye-tracking study
Emotional expressions are vital in human social interactions and effective communication. This study explored the influence of interoceptive awareness and self-focused attention on emotion perception from dynamic point-light dance movements along with the underlying eye behaviour. Eighty adult participants underwent random assignment into either the self-focus or control group, while considering age, gender, and interoceptive awareness. To assess interoceptive awareness, data were collected through both a heartbeat counting task and the implementation of the MAIA-2 Questionnaire. Self-focus group was supraminally primed with their self-face photograph with a neutral expression, prior to emotion recognition task. Consistent with prior research, the results revealed that participants with higher interoceptive awareness exhibited greater emotion recognition accuracy, alongside longer fixation durations, indicating increased attention to emotional stimuli. On the other hand, participants in the self-focus group demonstrated improved recognition of neutral stimuli. We interpret this finding that self-focus can enhance attention to the emotional expressions related to the self. Additionally, results revealed that females outperformed males in recognizing anger. Interestingly, females also displayed shorter fixation durations and higher fixation counts compared to males. While we found a similar fixation duration pattern in participants with low interoceptive awareness, females' shorter looking times at sad and neutral stimuli might suggest a potential higher experience or sensitivity to emotional cues. These findings were further discussed pointing to the roles of interoceptive awareness and self-focus in inferring the emotions of others as well as the underlying eye behaviour.
The influence of visual movement priming on novel and conventional metaphor comprehension: An eye-tracking study
Understanding metaphors is key to language processing. This research examined the influence of visual priming on action metaphor comprehension, addressing a critical gap in understanding cognitive mechanisms behind language comprehension. Based on the principles of embodied cognition, the research investigated how visual priming impacts comprehension of action metaphors, both novel and conventional, and literal action verbs. An experimental design was adopted, with eye-tracking technology used to capture eye movements as participants read metaphor-rich sentences. We executed a repeated measures ANOVA to analyze various eye movement metrics such as initial reading durations, the length of forward fixations, and the times spent on initial rereading. This was done to assess the influence of priming across varying categories of text. Results highlighted a significant effect of visual priming on first-pass reading times, especially for novel action metaphors, and forward-fixation and first-pass rereading times for all text types. The priming effects were confined to the target sentence. The study emphasized the facilitating role of visual priming in metaphor comprehension, hinting at the involvement of perceptual and sensorimotor systems in language comprehension. It also sets the stage for further research into the neural underpinnings of metaphor comprehension and broader priming modalities.
Muzikal metaforlar: Doğuştan ve nesnel
As in the recent approach cognition is embodied and metaphor theory of meaning metaphoricity of music is a topic that is mostly studied in cognitive musicology and cognitive linguistics and should be studied from the perspective of cognitive scientists. Musicologists use metaphors to describe the musical system itself in the music theory, music psychologists also use metaphors to describe perceptual facts like a tone is higher as in it resonates somewhere higher in the body or conceptual as in the tone's place in the musical spectrum. This conceptual part tells us that this kind of metaphor derives from a more complex activity of the cognitive system, a complex interaction of the environment with human posture and bodily movement during cognition of music. Metaphors are always in account when describing music. In my research I will try to determine if the musical metaphors are innate and objective by analysing how human posture and movement interacts in describing music by researching on bodily metaphors called image schemas using methods similar to Mihailo Antovic(2014) where he presents 5 different sound stimuli to children subjects and asks them to describe their experience and then analysing the subject answers using the image schemas and conceptual metaphor theory. The results showed musical comprehension is metaphorical and image schemas employed in subjects metaphors. In this research I examined a broader age range and compared musical instrument players and non players to see if their comprehension of music is also metaphorical and which image schemas they employ in metaphors. I used 9 different sound stimuli and 7 different image schemas to analyse with. According to results of this study, body-environment interactions which are related to force image schemas utilized in the metaphors the most.
Gruplar arası ilişkiler bağlamında atıf yanlılığı: Yerliler ve göçmenler örneği
Ultimate attribution error (UAE) is the tendency to attribute negative outgroup behavior to disposition factor and negative ingroup behavior to external circumstances. This study investigates the UAE committed by Turkish individuals in the context of intergroup relations between Syrian immigrants and Turkish citizens in. The purpose of this study is to investigate the impact of the other's out-group status and perceptual salience on the UAE. We intended to investigate these effects using a Virtual Reality configuration with virtual agents of a Turkish national and a Syrian immigrant. We hypothesized that Turkish citizens will make more dispositional attributions toward the Syrian immigrant agent in a negative scenario. Plus, the perceptually salient agent is expected to be attributed with more causality about the conversation and more dispositional. Results on the UAE yielded a significant interaction effect of Salience and Ethnicity. For the Syrian agent in a negative scenario, being visually salient resulted in higher ratings for the attribution of the negative behavior to personal decision. For the condition that Turkish agent is talking about a negative behavior, when Syrian agent is salient, the ratings for the same question were higher than the condition that Syrian agent is talking about a negative behavior, when Turkish agent is salient. Emotional and physiological (heart rate) reactions were also assessed, but yielded no significant results. This study contributes to the social and political psychology and cognitive science research by investigating both the perceptual salience and negative behavior effects in the context of ethnicity in VR environment.
Zaman algısının duyusal motor mekanizmaları: Öngörü mekanizmaları üzerinden bir zamansal kısalma incelemesi
Temporal binding refers to the perception that two events, which are related in terms of their cause and effect, occur closer together in time than they actually do. This effect not only creates a perceived cause-and-effect relationship but also compresses the time interval between events. Since the influential article on the intentional binding effect was published by Haggard, Clarke, and Kalogeras in 2002, researchers put forth several necessary conditions for the explanation of the effect. While proximity in time and predictability play a crucial role, it is primarily causality that determines the outcome rather than intentional action. According to Buehner (2012), causality is the fundamental factor behind the effect. Despite the productive work done in this area, there is still much to be discovered about the mechanisms that underlie temporal binding. In this thesis, we aim to investigate two main aspects of temporal binding. Firstly, we aim to determine whether the act of performing an action alone is sufficient to induce temporal binding or if outcome prediction plays a critical role. To achieve this, we conduct a series of experiments to compare congruent and incongruent outcomes, with the aim of uncovering the underlying mechanisms that cause this intriguing time distortion. Secondly, we examine the various factors that contribute to temporal binding. In addition to outcome prediction, we investigate the role of temporal control, which is the ability to dictate timing, in shaping our perception of time. We aim to understand how different factors affect temporal binding by analyzing each component.
Ön-eğitimli dil modelleri ile Türk işaret dili için işaret dili çevirisi
Sign Language Translation (SLT) is a machine learning task that aims to provide accessibility systems for the deaf and hard-of-hearing community. With the recent advances within the area, SLT technologies have shifted towards large-scale training with pretrained large language models (LLMs). However, most technologies and datasets are provided for American Sign Language (ASL) and British Sign Language (ASL). To achieve similar advances for Turkish Sign Language (TID) translation, we are proposing the first large-scale open-source translation dataset for TID, comprising over 500 hours of video footage and aligned Turkish translations by utilizing publicly available YouTube content. In this work, our dataset provides a scalable and reproducible framework for SLT research. We propose a comprehensive translation system with various inter-changeable components designed for SLT on an agglutinative language to compensate for the learning alignment between both low-resource languages, namely TID and Turkish. This body of work compares feature extraction strategies (Linear layers, Multi-layer Perceptrons, and Convolutional encoders), model sizes, and their pretraining approaches (multilingual versus Turkish-specific) to the effect on sign translation performance. Innovative training and evaluation techniques, including paraphrasing-based reference generation and sign language-specific augmentations, are also introduced for developing an SLT benchmark for TID.
Radikali radikalleştirmek: Radikal dışsalcı bir biliş biyolojisine doğru
In this thesis, I outline a radically externalist approach to cognitive science, explain why such an approach is needed, and discuss the potential benefits it offers. I examine the dominant divisions in the field, i.e. internalism vs. externalism and representationalism vs. anti-representationalism, and track the argumentative steps that yield these positions. Along the way, I identify key background assumptions, particularly realism, multiple realizability, and the autonomy of the special sciences. I argue that these assumptions underlie most theoretical frameworks in cognitive science and that they ultimately lead to the problem of mental causation and the hard problem of content. I claim that these problems disappear once we abandon those assumptions. In their place, I defend an anti-realist stance, draw on the new mechanistic philosophy of science, and propose a new tool: the Naturalistic Coherence Criterion. I argue that this framework points us toward a radically externalist cognitive science, one that remains agnostic about the metaphysics of mind and avoids unnecessary theoretical burdens.