Adaptive visual search in the distractor previewing effect: Focusing on feature previewing history and task context

신은삼 한국인지및생물심리학회 2015 한국심리학회지 인지 및 생물 Vol.27 No.2

The nature of adaptive visual search was investigated using the distractor previewing effect (DPE). In a color oddball search task, search times increase for targets whose colors were previewed in a preceding target-absent display (TAD) compared to distractors whose colors being previewed in the TAD. Thus, target-color previewing (TP) trials are typically slower than distractor-color previewing (DP) trials, and this response time (RT) difference is the DPE. For the purpose of the study, color previewing history was varied to examine temporal integration of visual experience with trial-by-trial adjustments being simultaneously made, and task context were manipulated to induce (un)predictable target appearance times. TADs ranging from 0 to 5 (Exp. 1) or from 0 to 2 (Exp. 2) were presented prior to a target-present display, and the number of TADs was blocked (Exp. A) or randomized (Exp. B), resulting in four experiments 1A, 1B, 2A, and 2B being conducted. All experiments similarly showed: (a) increased RTs for TP than for DP trials; (b) increased RTs with increasing TADs; and (c) different DPEs as a function of the TAD. In addition, Experiments 2A and 2B showed that search times depended on the colors of the TAD, immediately rather than remotely preceding the target display. Differences were also found between the block (predictable) and random (unpredictable) designs. Compared to no color previewing trials, all TP trials were slower in both designs, but DP trials differed in that RT was faster in all TADs in the unpredictable context but only in the 1TAD and 2TADs in the predictable context. Moreover, the unpredictable context did not showed a DPE after one TAD presentation unlike the predictable context. These results suggest that (a) visual experience leaves memory traces and is accumulated into memory while trial-by-trial adjustments are made; and further (b) depending on the demand that a given task requires humans exert their top-down control of attention accordingly.

Interactions between Visual Working Memory Representations in Grouping Contexts

신은삼,황성민,정상철 한국인지및생물심리학회 2020 한국심리학회지 인지 및 생물 Vol.32 No.4

Studies have shown that stimulus representations interact in visual working memory (VWM). Using Gestalt grouping cues, we investigated how VWM representations of individual stimuli interact in grouping contexts. Two closely located colored circles (proximity) were connected or separated by a line (connectedness). These pairs were shown in memory and test arrays. Participants performed color change detection tasks in which they were asked not only to detect changes but also to locate the changed items. Color change was made to one (Experiment 1) or two (Experiment 2) item(s) in each test array. In Experiment 1, individual items grouped by both proximity and connectedness showed lower detection performance than those only by proximity. In Experiment 2, the colors of two stimuli changed in the same group (intragroup) or across different groups (intergroup). As in Experiment 1, the same grouping effect was observed in the intragroup-change condition. In addition, the change detections were better in the intragroup- than intergroup-change condition. This effect was reversed when data obtained from correctly detected (not necessarily located) trials were analyzed. Collectively, change detections of individual items differed depending on grouping strength, group membership status, and levels of data analysis, suggesting that items represented in VWM affect one another in a hierarchical structure.

he Effects of Aging and Physical Fitness on Working Memory Capacity

신은삼,Carrie Brumback-Peltz,Brian A. Gordon,Edward McAuley,Gabriele Gratton,Monica Fabiani 한국인지및생물심리학회 2012 한국심리학회지 인지 및 생물 Vol.24 No.2

Previous studies indicate that physical fitness plays a protective role against age-related cognitive decline (e.g., Colcombe & Kramer, 2003). Using event-related potentials (ERPs), we investigated age-related cognitive decline in working memory processing and whether physical fitness positively influences working memory capacity in older adults. Data from 13 younger and 25 older adults (tested for their physical fitness) were analyzed. The participants performed a modified Sternberg memory search task while ERPs were recorded. The memory set was presented in upper-case letters, with a memory set size varying from 2 to 6. A lower-case probe letter following the memory set required a positive (“old”) or negative (“new”) response. Behavioral data showed age-related but not fitness-related differences. The ERPs, elicited by the memory set, showed (a) an age effect in the posterior P1 component, and (b) age and fitness effects in the frontal negativity. These results suggest that age affects general working memory processes, but physical fitness may help specifically to reduce the decline of working memory capacity.

편측성 준비 전위(lateralized readiness potential): 대측 통제를 이용한 운동 관련 전위에 관하여

신은삼 한국인지및생물심리학회 2012 한국심리학회지 인지 및 생물 Vol.24 No.4

The lateralized readiness potential (LRP) that uses the contralateral organization of motor control is derived from event-related brain potentials (ERPs). Because of the high temporal resolution of the technique, it has been a beneficial research method investigating mental chronometry in human information processing. In particular, studies using the LRP have shown evidence that information flows continuously and concurrently in the brain. In this review, I introduced the background of the LRP emergence, basic principles behind its arithmetic computations, LRP types, data analysis and statistical tests. Finally, I reviewed studies in which the LRP was used and applied for various purposes, and suggested that the LRP can contribute to expanding the scope of brain research in the country. 신경계의 운동 체계가 대측적으로 조직화되어 있음을 이용하여 개발된 편측성 준비 전위(LRP: lateralized readiness potential)는 사건관련전위(ERP: event-related potential)에서 도출되는 특수 파형으로서 그것의 높은 시간적 해상도를 바탕으로 심리 시간분석법(mental chronometry)적 연구 발전에 큰 공헌을 해왔다. 특히 인간의 정보처리 양식이 동시적이고 연속적이라는 증거를 제공하면서 그 유용성을 확장해왔다. 본 논문에서는 LRP의 발달 배경, 도출 원리, 종류, 분석 및 검증 방법을 개관하였고 LRP를 이용한 응용 연구 또한 소개하였다.

Memory Representations in Visual Working Memory: Representational Quality and Memory Access

신은삼,Monica Fabiani,Gabriele Gratton 한국인지및생물심리학회 2013 한국심리학회지 인지 및 생물 Vol.25 No.4

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.

노화 관련 뇌인지 변화와 운동의 긍정적 영향

신은삼(Eunsam Shin) 한국인지과학회 2013 인지과학 Vol.24 No.1