Recognition memory - a type of episodic memory in long term memory - is known in the literature to be affected by emotion, aging and the modality of the presented stimuli. The major aim of this study was to investigate whether emotional stimuli enhances recognition memory. Another goal was to observe whether modality and aging effects are present and differentiable in a non-Western subject sample. In literature, emotion studies were based on mainly two dimensions of emotions: valence and arousal. However, the contribution of these two dimensions to the enhancement of recognition memory still needs clarification. The present study investigated specifically the effect of valence on recognition memory. Moreover, the experimental manipulations of this study allowed observing the effect of valence on recognition memory due to normal aging. Since modality of the presented stimuli is a major confounding factor on recognition, separate experiments involving visual and verbal stimuli were designed. Pictures and words were selected on the basis of valence and arousal ratings. The stimulus set of the visual recognition memory task consisted of the pictures selected from the International Affective Picture System (IAPS) (Lang et al., 2005). The stimulus set of the verbal recognition memory task was constructed from partially standardized material for affective norms of Turkish emotional words (METU TEW), which was developed as a part of this study. METU TEW allowed selecting words with positive, neutral and negative valence while controlling arousal. The results replicated two findings reported in the literature: (1) younger adults recognized more accurately than older adults / (2) recognition memory was enhanced for visual items regardless of age and valence. Interestingly, this study revealed that recognition memory was not enhanced for emotional stimuli varying only on the valence dimension. More specifically, there was a decline in recognition memory for positive items and no change was observed for negative items, regardless of age. Further analysis also revealed that there may be differential effects of abstractness and concreteness on verbal recognition memory in aging.

Turkish speakers differentiate the blue region of color spectrum into mavi (blue) and lacivert (dark blue) / whereas non-Turkish speakers in this study had only one color term in the blue region. The present study aimed to explore the predictions of the Linguistic Relativity Hypothesis. Operationally, Categorical Perception (CP) effects were used. In Experiment 1, Turkish speakers performed a naming task to determine an average category boundary between mavi and lacivert. In Experiment 2, both Turkish and non-Turkish speakers&rsquo / color-difference detection thresholds were estimated on the average boundary as well as within the mavi and lacivert categories. The thresholds were also estimated in the green region, in which both groups had only one color term. 2-TAFC method, which eliminates the effects of memory or labeling and isolates the perceptual processes, was used to estimate the thresholds. Turkish speakers, and not non-Turkish speakers, were predicted to show CP effects only in the blue region: thresholds should be lower on the boundary than within-category. The result revealed that Turkish speakers&rsquo / color-difference detection thresholds were lower than those of non-Turkish speakers both in the blue and the green regions. The difference in the green region does not rule out the LRH. It is possible that this difference resulted from the limitations of the study. Finally, in Experiment 3, Turkish speakers&rsquo / thresholds were also estimated on their individual boundaries. The patterns of the thresholds revealed by Experiment 3 were similar to the pattern of the thresholds in Experiment 2.

The perceptual reality of the music theoretical relation between the Neapolitan chord and the dominant / and the secondary dominant chord and its diatonic associate was investigated within the chord priming paradigm. In Experiment 1, expectation towards the dominant chord after the Neapolitan chord was observed in Turkish musicians and non-musicians with piano timbre. In Experiment 2, expectation towards the dominant chord after the Neapolitan chord was observed in European musicians but not in European non-musicians. In Experiment 3, Turkish non-musicians were tested with Shepard tones / but it was not possible to observe any priming effects. To understand effects of cultural background on the difference between the results of Experiments 1 and 2 further studies are necessary. In Experiments 4-5, the perceptual reality of the relation between the secondary dominant chord and its diatonic associate was investigated in Turkish non-musicians. In Experiment 4, chord sequences that included secondary dominant chords were played with Shepard tones / and they were scrambled with 2by2 scrambling algorithm. Experiment 5 was identical with Experiment 4, except chord sequences were played with the piano timbre. Experiment 6 was identical with Experiment 5, except chord sequences were scrambled with 4by4. However, in Experiments 4-6 detrimental effects of scrambling sequences that include secondary dominant chords on the priming of chords were not observed. Turkish non-musicians did perceive the relation between the secondary dominant chord and its diatonic associate. In neural network simulations of this thesis it was shown that statistical learning from the musical environment with self-organization could be achieved without committing the questionable assumptions of previous studies.

The aim of this study was to find if manipulating fluency, that is, the ease of processing, could affect confidence ratings about whether an event occurred in the respondents&rsquo / past. To test the familiarity misattribution hypothesis, which states that familiarity caused by fluent processing can be misattributed to past experience if the source of fluency cannot be identified, two methods were used: a revelation task, which was anagram solving and repetition priming. In the revelation task the familiarity misattribution hypothesis and the activation based hypothesis were tested by presenting one of the words in each one of the Life Event Inventory (LEI) items as an anagram or an unrelated anagram before the LEI, respectively. Higher confidence ratings for LEIs with an anagram compared to LEIs without anagrams would indicate that a revelation effect. A revelation effect was not observed for either condition. Therefore, the previous findings of revelation effect for autobiographical memories (Bernstein et al., 2002) could not be replicated when Turkish counterparts of LEI and anagrams were used. In the repetition priming experiments, the participants&rsquo / awareness of the source of fluency was manipulated by presenting either a subliminal or a supraliminal prime before they responded to a LEI item. The prime was either the same as the verb of the LEI sentence, or a different verb. Participants gave higher confidence ratings if subliminal primes were identical to, rather than different from, the verb of the sentence. If the participants were aware of seeing the primes, this difference disappeared. These results were consistent with the familiarity misattribution hypothesis.

This thesis focuses on modeling Expectation-Violation Effect, which is the superior recall of weakly associated pairs of words over strongly associated pairs. The goal of this thesis is to provide an exploratory computational model. A virtual experiment is conducted based on the datasets used in the psychological experiment by Amster et al. (1992). The computational modeling of this phenomenon is carried in the medium of ACT-R cognitive architecture.