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- P-ISSN1226-9654
- E-ISSN2733-466X
- KCI
ISSN : 1226-9654
Vol.25 No.4
Abstract
Two experiments were conducted to investigate the impact of color, spatial frequency and shape on chromatic induction. In experiment 1, the effects of inducing colors and test colors were examined. Stimuli were S-cone patterns and L-cone patterns of concentric circles. The result of experiment 1 showed that chromatic induction occurred both with S-cone and L-cone patterns. In particular, chromatic induction was strong when inducing colors in the S-cone patterns were purple. Test colors also affected chromatic induction. In experiments 2, the effect of spatial frequency and shape of the stimulus were tested. Three types of shape were used as stimuli; concentric circle like in experiment 1, straight line and arc. The result of experiment 2 showed that, if spatial frequency was higher chromatic induction was strong in all shape of stimuli. These results imply that chromatic induction is concerned with early stage of visual information process.
Abstract
The present study aimed to examine the properties of VWM consolidation and comparison processes according to the interference driven by simultaneous and backward masks against sample and test items in a color-change detection task. To accomplish this, we displayed the mask stimuli that would superimpose either the sample or test items, simultaneously with or immediately after the sample or test items respectively. When the simultaneous masks were displayed, change detection accuracies in each sample- and test-mask condition rapidly decreased as the display setsize increased. However, when the backward masks were displayed, the change detection was relatively efficient for the test-mask condition compared with the sample-mask condition. When there was no mask, the detection accuracy was much higher than when the masks were present. The strong interference against the sample items observed both in the simultaneous- and backward-mask conditions shows that there is an information-processing bottleneck in the VWM consolidation process. Whereas the evident interference against the test items by the simultaneous-mask rather than by the backward-mask indicates that just as in visual search, the VWM comparison process may undergo a detection process for a salient pop-out elicited by a distinct visual difference across memory and perception.
Abstract
Previously, Shin and colleagues (2006) reported sequential deflections of encoding-related lateralization (ERL) waveforms in event-related potentials (ERPs). One of these deflections, observed at posterior electrode sites (P7/P8), started about 400 ms poststimulus, and was dependent on both memory set-size and the degree of matching between memory-sets and test probes. These suggest that there is a level at which relations among items and degree of memory access are important in visual working memory. Based on these findings the present study investigated representational quality and degree of memory access. It was hypothesized that representational quality could be lowered by competition between stimuli (local suppression), and that degree of memory access be lowered when probes only partially match memory-set stimuli (partial matching). The relative distance (close or far) and similarity (homogeneous or heterogeneous) between memory-set stimuli were varied. ERPs were recorded while participants made old or new responses to single probes preceded by memory-sets (of size 2 or 4). ERL results obtained from 33 participants showed (a) that large ERL effects were found at the P7/P8 sites with a latency of 400-700 ms from probe onset, similar to Shin et al. (2006); (b) that significant ERL activity was observed only for the homogeneous memory-sets presented far apart; and (c) that the heterogeneous memory-sets presented nearby showed significantly smaller ERL activity than set-size 2 memory-sets (representing no-suppression and complete matching). These results support a hybrid of the local suppression and partial matching hypotheses, suggesting that representational quality and degree of memory access can jointly influence visual working memory processing.
Abstract
The current study utilizes negative emotional facial expressions (fearful, angry) that are known to reliably stimulate the amygdala, and investigates their effects on decision making performance in threat situations. Results indicate that there were no significant differences in terms of accuracy when the subjects were asked to search and respond to enemy troops followed by exposure to fearful versus angry facial expressions for 3 seconds. However, we observed a statistically significant difference in response times. We found that the subjects required less time to respond to the targets when they were exposed to angry facial expressions, compared to when they were exposed to fearful facial expressions. This could be explained by the some of the behavioral consequences of these emotions (angry-aggression, fear-freezing). In sum, while both are categorized as negatively valenced emotions, perceiving either fearful or angry facial expressions can differentially impact a soldier's performance in detecting and responding to enemies in hostile and threatening situations.
Abstract
This research examined whether midfrontal EEG asymmetry(FBA) influenced event related potential(ERP) to affective stimuli. Participants completed both Positive and Negative Affect Schedule(PANAS) and behavioral inhibition system and behavioral activation system(BIS/BAS) scales. Following resting FBA measure, ERPs were recorded while participants viewed International Affective System(IAPS) stimuli. Positive, negative and neutral pictures were used as infrequently occurring target stimuli and control pattern stimuli were used as frequent standard stimuli in oddball paradigm.. The P300 and late positive potential(LPP) components of the ERPs elicited by three types of affective pictures and control stimuli were analysed. Affective pictures elicited significantly higher ERPs relative to control stimuli. Compared to the right midfrontal activation group, the left midfrontal activation group exhibited higher ERPs to positive pictures and higher PA and BAS, but lower ERPs to negative pictures and lower BIS. FBA, BAS and BIS are significantly correlated with ERP components. In hierarchical regression analysis, FBA predicted higher ERPs to positive pictures and lower ERPs to negative pictures whereas BIS predicted higher ERPs to negative pictures. This results suggest that the trait motivational direction hypothesis is more plausible than the valence hypothesis to explain the mechanisms of frontal brain asymmetry in processing emotional stimuli.
Abstract
Baddeley(1986, 2000) proposed a working memory model which is composed of the executive control system, the visuospatial sketchpad, and the phonological loop. In studying the nature of the phonological loop, a variety of articulatory suppression behaviors have been applied in experiments, but their effects have not been intensively investigated. This study tried to probe effects of articulatory suppression behaviors, especially on working memory performances. Subvocal and overt speech forms, two speeds of rehearsal (articulation), presence or absence of suppression monitoring, and several kinds of suppression words were contrasted while participants tried to remember memory items auditorily presented. Working memory performances were measured by the memory span (Exp. 1) and the number of correctly recalled items (Exp. 2 & 3). Results are as follows: Overt articulatory suppression (Exp. 1), slow speeded rehearsal (Exp. 1) and non-condensation of suppression words (Exp. 2), and monitoring suppression words (Exp. 3) had more negative effects on working memory performances than its counterpart condition, respectively. In the subvocal articulatory suppression condition of Exp. 1, working memory performances varied with the rehearsal speed. And in the non-condensed condition of Exp. 2, the performances varied with kinds of suppression words. It was concluded that articulatory suppression behaviors have effects on the performances of working memory system, and these effects resulted from speech automatization of articulatory suppression behaviors. The results and conclusion of this study are not consistent with Baddeley's model which has not observed the effects of articulatory suppression behaviors. From this it follows that Baddeley's model should be reconfigured to include the effects of articulatory suppression behaviors.
Abstract
Successful feedback learning relies on the individual's ability to consistently adjust behavior, based on repeated stimulus-response-outcome experiences, and ability to retrieve previously learned information from memory. The present study investigated the neuroanatomical bases of individual differences underlying two types of performance, acquisition and memory, during feedback based S-R learning, using voxel-based morphometry (VBM). Whole-brain structural magnetic resonance imaging (MRI, 3T) scans were obtained from healthy young subjects (N = 22: M/F = 4/18). Multiple regression analysis revealed that individual differences in learning rate were positively correlated with gray matter volume of the left superior parietal region, indicating that efficiency in acquisition may be associated with attentional control. The individual differences in memory rate were positively correlated with volume of the right posterior hippocampal region, which is known to be involved in formation of long-term memory. These results demonstrate a double dissociation between learning-acquisition and memory-performance.
Abstract
One of the main factors that explain individual differences in working memory capacity is cognitive styles. Although it was proposed that cognitive style consists of three independent dimensions of object, spatial and verbal, the relationship between working memory and the three-dimensional cognitive style has been unknown. Thus, we sought to examine the validity of the Korean version of the Object-Spatial Imagery and Verbal Questionnaire (OSIVQ; Blazhenkove & Kozhevnikov, 2009) (experiment 1), and the relationship between cognitive style and working memory by evaluating the differences in performance on working memory tasks according to individuals' cognitive styles (experiment 2). In the experiment 1, we found that the Korean version of OSIVQ consisted of three main factors (Object, Spatial, and Verbal) and showed satisfactory reliability and validity. These results were repeatedly observed for another sample. In the experiment 2, we found that the greater object style was preferred, the higher accuracy in the object task was scored and that the greater spatial style was preferred, the higher accuracy in the spatial task was shown. In other words, these results demonstrate that there is a close relationship between cognitive style and working memory. Our results suggest that repetitive use of a particular information processing method, according to the preference on the cognitive styles, can lead to improvement in relevant working memory capability.
Abstract
The aim of the present study is to elucidate the differences in neural correlates in a vigilance task performance according to stress level between extraverts and introverts. Forty-three subjects were assigned to two groups (21 extraverts; 9 males, 22 introverts; 9 males). Subjects in the two groups performed a vigilance task either under a social stress or not during the event-related potential (ERP) recording. Results showed that the response accuracies of both groups in the stress condition were higher than those in the no-stress condition. ERPs revealed that (1) N2-P2 peak-to-peak amplitudes and contingent negative variation (CNV) mean amplitudes in the introversion group were significantly greater than those in the extraversion group, (2) the N2-P2 peak-to-peak amplitudes increased significantly at Fz site in the stress condition in the extraversion group. These results suggest that introverts may sustain higher level of arousal than extraverts, regardless of stress condition, and extraverts may show augmented arousal or attention levels, specifically in performance under stress.
Abstract
Auditory fear memory is represented as long-lasting changes in the two input pathways into the lateral nucleus of the amygdala (LA): thalamo-amygdala and thalamo-cortico-amygdala pathways. Previously in our laboratory, we have shown that plasticity in the thalamo-amygdala pathway is critical for fear memory formation when electrical stimulation of the medial division of the medial geniculate nucleus of the thalamus (MGm) was used as the conditioned stimulus (CS). This short-circuit approach with the electrical brain stimulation as the CS (eCS) allowed us to test the efficacy of a particular pathway of interest without involving other sensory pathways. In the current study, we tested whether synaptic plasticity in the cortical pathway could support fear memory formation in rats by pairing the electrical stimulation of the secondary auditory cortex (Te3) with the footshock unconditioned stimulus (US). Following six paired presentations of the eCS and US, rats in the Te3-paired group showed significant level of freezing in the eCS-only test session, compared to a group that received unpaired presentations of the eCS and US. In addition, we also included MGm-paired group that received paired presentation of the MGm stimulation and US. The level of freezing to the eCS in the test session was comparable between Te3- and MGm-paired group. To examine the long-term maintenance of conditioned fear memory, freezing was measured 3 weeks after the acquisition session with the eCS. Both MGm-paired and Te3-paired groups showed considerable level of freezing and there was no significant difference between the two groups. In conclusion, both thalamic and cortical input pathways into the amygdala effectivly support fear conditioning when brain stimulation was used as the CS, suggesting that learning-induced changes in either the thalamo-amygdala or the cortico-amygdala synapse might be sufficient for storing fear memory.