Effects of level of processing and emotional stimuli on the recognition memory performance in healthy and high depressive symptom groups

The aim of this study is to investigate the memory and metacognition performances of normal participants and participants with high levels of depressive symptoms for different information processing levels (Deep Processing, Shallow Processing) and emotion categories (Neutral, Happiness, Disgust, Fear, Anger and Sadness). Study was conducted with 192 (138 female, 54 male) vounteer participants between 17-35 years old (𝑋 ̅ = 20.84, SS= 2.39). 131 (90 female, 41 male) participants were included in the normal group and 61 (48 female, 13 male) were included in the depressive symptom group. All participants were selected from undergraduate and graduate students in different departments of Hacettepe University. The computer task used in the research consists of two basic phases, encoding and recognition test. These two phases were implemented in separate blocks for stimulus types (words and pictures). It was randomly determined which stimulus type participants would see first. In encoding phase, 72 words or 72 pictures were shown to parcipants at one of the procesing level (Deep Procesing, Shallow Processing) which randomly assiggned. Participants were asked to classify stimulus as "positive" or "negative" at deep level processing; "right" or "left" of the screen at shallow level processing. Immedeately following the encoding phase, simple mathematic problems were presented as distraction task to make the recognition test more difficult. After the distraction task, a recognition test consisting of a total of 144 stimuli (72 new, 72 old) were shown and participant were asked to evaluate every stimulus as "old" or "new" stimuli. After every "old/new" decision participants rated their confidence about decisions on a 10-point Likert scale (1= not confident at all, 10 = compeletely confident). Confidence judgements were made for every test item separately. d' and matecognition scores were analyzed with 2(Group: Normal ve Depressive Symptom) x 2(Level of Processing: Deep Processing and Shallow Processing) x 2(Test Prior Knowledge: Prior Knowledge Exists ve Prior Knowledge Not Exists) x 6(Emotion Categories: Happines, Afraid, Anger, Sadness, Disgust, Neutral) mixed ANOVA with repeated measures on the last two factors. Results indicate that participants had a better recognition for both words and pictures in deep pocessing level. Higher d' scores were observed in the intentional condition (a prior knowledge that they would be tested) for the words but there were not any significant effect in the incidental condition (having not prior knowledge that they would be tested after encoding). Similarly, the effect of emotion categories differed according to the stimulus type. Highest d' score was found in the Neutral category for words, for pictures Disgust had the highest d' score. In the metacognition analyses part, two metacognitive scores were calculated: knowing and not knowing. For pictures, there were higher scores in the deep information processing level for both types of metocognitive score categories. While in the intentional condition for the words, the level of information processing effect was not seen, high metacognition scores were observed in both knowing and not knowing categories. In addition, for pictures, the highest scores were measured in Happiness emotion category for both knowing and not knowing metacognition categories. However, for words, Disgust and Neutral emotion categories in the knowing category, and Happiness and Disgust categories in the not knowing category had the highest metacognition scores.