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Vol.20 No.3

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Abstract

To investigate how the mechanisms of memory encoding were influenced by the verbalizability of nonverbal material and the imageability of verbal material, an event-related fMRI study was performed. Subjects were asked to intentionally memorize the mixtures of concrete words, object pictures, and abstract patterns and then perform recognition judgement test. Recognition scores revealed the superior accuracy for pictures and the worst accuracy for abstract patterns. Analyses of signal change ratio at the superior PFC(BA 6), superior parietal lobe(BA 7), and medial temporal lobe revealed right-lateralized frontal activation during abstract pattern encoding, no lateralized frontal activation during word and picture encoding, and higher right-frontal activation during abstract pattern encoding than word and picture encoding. No lateralized parietal activation during encoding was observed on all types of learning materials, and higher bilateral-parietal activation during abstract pattern encoding than during word and picture encoding was observed. No lateralized, nor differential MTL activation during encoding was observed on all types of learning materials. Analyses of contrast among learning materials revealed similar activation patterns at superior PFC and superior parietal lobe but different activation patterns at MTL, showing higher bilateral-MTL activation during word and picture encoding than during abstract pattern encoding as well as higher right-MTL activation during picture encoding than during word encoding. The overall bilateral activation patterns of words were similar to those of pictures, but activation patterns of words and pictures were different from those of abstract patterns. The data support the code-specificity rather than material-specificity hypothesis and indicate that the neural mechanisms of intentional memory encoding were dependent on the types of learning materials.

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Abstract

In Japanese learner's discriminative learning of the three-way phoneme distinction on Korean alveolar stop sound, the learning effects on the discrimination of distinctive phonemes by three tasks (identification, same-different discrimination, oral practice) were compared and examined through Experiment 1 and 2. In the first experiment, examining the discriminative learning effects by three tasks run independently, increment of phoneme distinction was the largest for the identification-task group and the next the same-different discrimination-task group and the oral practice group successively ordered. It was shown that the learning effect by phonemes differed depending upon the learning tasks. Inspecting the false-response patterns of phoneme identification and the acoustic stimuli produced by 6 speakers, the differential effect along three phonemes could be interpreted as a result of responding selectively to acoustic cues such as VOT and F0. The second experiment, scrutinizing more effective perceptual learning task, compared two successive combination of the identification and the same-different discrimination tasks. The learning group that learned firstly by the same-different discrimination task and secondly by the identification task, yielded phoneme discrimination effect more than the other group with the reversed task order. The implication of the two experiment on the previous studies for phoneme discrimination and the possibility of constructing effective learning tasks were discussed.

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Abstract

Change-detection necessitates comparison of visual working memory (VWM) representations with perceptual inputs (Hyun, 2006). The current study tests masking interference with consolidation of test items being compared with sample items in memory. Subjects performed a change-detection task where they were asked for reporting a color change between two sets of colored boxes. In masking trials, complex pattern masks were presented at each item position 17ms after the test display disappeared. Change-detection performance was worse in masking trials than no-masking trials, and Event-related potentials (N2pc) was virtually absent when masks were present. The interference effect observed both behaviorally and electrophysiologically supports for the presence of a comparison process between memory and perceptual inputs.

; ; (北海道大學) ; (Univ. of Pittsburgh) pp.179-202 https://doi.org/10.22172/cogbio.2008.20.3.004
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Abstract

Cross-linguistic differences in computation of phonological codes were explored in three experiments. Hanja words―those words used in Korean and Japanese but originated from Chinese―were presented in Hangul, Kanji, and Hanzi for Korean, Japanese, and Chinese participants, respectively. In addition to this script difference, stimulus degradation effects and word frequency effects were measured in naming latencies. High-frequency words were named faster than low-frequency words, and non-degraded words were named faster than degraded words in all three languages. The within-language interaction effects of these two variables were small enough to be neglected. However, the effect sizes of these variables varied across languages: while stimulus degradation effect was smaller in Chinese than both in Korean and in Japanese, frequency effect was much smaller in Korean than both in Chinese and in Japanese. The results suggest that even though all prints appear to be processed in the same way―as the Universal Hypothesis puts it―at macro-levels, the computation of phonological codes of Hanzi/Kanji words relies more on lexical processes and that of Hangul words relies more on sub-lexical processes at micro-levels.

The Korean Journal of Cognitive and Biological Psychology