초록

Abstract

How does working memory (WM) load affect concurrent visual selection? A previous study has shown that high WM load increases functional magnetic resonance imaging (fMRI) signals for task-irrelevant information, suggesting that visual selection is impaired with a WM load. In contrast, recent behavioral experiments demonstrated that visual selection can be enhanced if the type of WM load overlaps with distractor processing. Using fMRI, the current experiment extends the previous behavioral findings by demonstrating that loading WM with face images can reduce task-irrelevant face processing in the face-selective cortical region, the fusiform face are (FFA). In Experiment 1, while remembering a famous (low load) or novel (high load) face, participants performed a politician-athlete classification for names overlaid on distractor faces. In Experiment 2, participants remembered one novel face (low load) or three different novel faces (high load) for the WM task. In both experiments, high WM load enhanced target selection. The FFA responses were reduced to face distractors when WM was demanded. We further demonstrated that these results were not driven by load-dependent baseline shifts in the FFA activity in Experiment 3. In conjunction with previous studies, the current findings suggest that WM load can attenuate distractor interference and improve target selection when the contents of WM shares limited-capacity processing with distractors.

초록

Abstract

The present study investigated perception of biological motion (BM) focusing on two issues. Although it has been reported that the right posterior region of the superior temporal sulcus (pSTS) is more strongly activated than the left pSTS when viewing BM, the reason is not well understood. Second, most previous studies have focused on the accuracy of BM perception while reaction time (RT) to BM compared with other motion signals remains relatively unknown. BM and non-BM stimuli were briefly presented in each (left and right) visual field in Task 1. In Task 2, the same stimuli were displayed at the center. RT and accuracy were measured in both tasks. To explore a possible perceptual correlate of the neural anisotropy in the pSTS, RT and accuracy between the two visual fields were compared (Task 1). To examine the efficiency of BM processing, RT and accuracy differences between BM and non-BM were examined (Task 1 and Task 2). The result from Task 1 demonstrated that RT was faster and accuracy was higher when BM was presented in the left visual field. This suggests a perceptual correlate of greater right pSTS activation associated with BM perception. The results from Task 1 and Task 2 revealed that BM was detected more quickly and accurately than non-BM, suggesting that BM processing is more efficient than other global motion processing when information is limited by brief exposure. Analysis of error trials from the two tasks also suggests a perceptual bias of judging ambiguous motion signals as BM.

초록

인출 유도 망각이란 이전에 학습한 항목을 반복적으로 인출하는 것이 인출시키지 않은 관련 항목의 망각을 일으키는 현상을 말한다. 본 연구는 인출 유도 망각에 미치는 부적 정서의 효과를 조사하게 위해 계획되었다. 두 개의 실험에 총 189명의 참가자가 자원하였다. 실험 1에서는 범주의 정서 강도를 조작하여 RIF를 관찰하였다. 학습 목록의 정서가는 각 범주에 해당하는 중성 단어에 정서적 형용사를 함께 제시하여 정서가를 덧붙이는 방식으로 조작되었다. 참가자들은 먼저 총 6개 범주에 속한 6개씩의 범주 내 예제 단어들을 학습하였다. 이후에 참가자들에게 범주 내 단어들의 절반에 대한 인출 연습을 실시하였다. 참가자들은 최종적으로 이전에 학습했던 모든 단어들에 대한 회상 검사를 받았다. 실험 1의 결과 중성범주 목록과 약한 정서범주 목록에서 RIF가 관찰되었다. 실험 2에서는 모든 범주 내 자극이 부적인 조건, Rp+가 부적이고 Rp-가 중성인 조건, Rp+가 중성이고 Rp-가 부적인 조건, 그리고 모두 중성인 네 개의 조건으로 조작하였다. 인출연습을 시킨 단어들(RP+)이 중성이고 인출연습을 시키지 않은 단어들(RP-)이 부적정서인 범주 조건을 제외하고 모든 조건에서 RIF가 관찰되었다. 두 실험의 결과는 강한 부적 정서자극에 대해 RIF가 관찰되지 않을 가능성이 있다는 점을 제안한다.

Abstract

Retrieval-induced forgetting implies that repeatedly retrieving a subset of previously studied items can cause forgetting of related non-retrieved material. The present study was designed to investigate the effect of negative emotion on retrieval-induced forgetting(RIF). Two experiments were conducted with 189 volunteers. The emotional valence within lists was manipulated as attaching emotional adjectives on neutral words in each category. Participants studied words from total 6 categories and it consisted of neutral and emotional stimuli in each category. And then they repeatedly retrieved a subset of the neutral material. Later, a recall test was conducted for all previously studied items. When participants studied neutral and negative stimuli in one category and then only repeatedly retrieved a subset of the neutral material (RP+), retrieval practice on the neutral items caused effect of the retrieval-induced forgetting on the emotional stimuli (RP-). Namely, the emotional valence had a different effect on retrieval-induced forgetting across RP+ and RP- conditions. And the effect systemically varied with the intensity of emotionality in the lists.

초록

손 움직임과 손에 일어나는 촉각은 시각 움직임 지각에 영향을 준다고 알려져 있다. 그렇지만 이전 연구에서 이 두 요인의 효과는 독립적으로 검증되었다. 본 연구는 이 두 요인이 모두 투입되었을 때 움직임 지각이 어떻게 달라지는지를 살펴보았다. 세 실험에서, 참여자는 두 점이 수평 방향으로 움직일 때 서로 통과하는 움직임 또는 되돌아오는 반동 움직임으로 애매하게 보이는 움직임 자극을 보면서 자신들의 손을 두 점의 움직임과 같이 움직였는데, 박수치듯이 두 손을 가운데서 되돌아오게 하거나 서로 지나치게 하였다. 실험결과, 손을 지나치게 했을 때 두 점의 지나침 움직임이 손을 지나치게 했을 때보다 더 많이 보고하였다. 그런데 두 단서가 서로 되돌아 오는 조건을 만들었을 때 서로에 대한 움직임 지각 효과가 상쇄되었다. 또한 손을 박수치듯 가운데로 움직였다 되돌아오는 조건은 두 점의 반동 지각을 충분히 이끌지 못했는데, 이는 손을 움직일 때 발생하는 운동 감각이 시각 움직임에 미치는 영향은 두 점이 한 방향으로 지나치는 움직임 지각에 제한됨을 시사한다.

Abstract

Tests show hand movement and hand touch influence the perception of visual motion. However, previous studies tested these two factors independently. This study examined how differently participants might disambiguate ambiguity in visual motion with simultaneous manipulation of hand movement and touch. While participants observed a streaming/bouncing ambiguous motion display, consisting of two disks that moved horizontally, they moved both hands toward each other, along with the two disks, and either returned from the middle or continued, crossing each other, either with or without the hands touching in the middle. The results supported previous studies showing hand crossing induced greater visual streaming perception, while hand touching induced greater visual bouncing perception. However, when both cues conflicted, their effects decreased significantly, suggesting kinesthetic information and cutaneous touch information additionally influence vision. In addition, the results showed hand returning, alone, did not induce visual bouncing perception, suggesting that kinesthetic information may be effective only for motions in which an object moves along a straight or smooth trajectory or only during initiation of the object's motion.

초록

본 연구는 상관부트스트랩(bootstrapped correlation difference, BCD)법과 진폭부트스트랩(bootstrapped amplitude difference, BAD)법을 이용하여 P300-기반 유죄지식검사의 탐지정확률을 도출하고 이를 비교하였다. 강기영과 김영윤(2010)의 연구에서 유죄집단과 무죄집단으로 분류된 총 24명의 피험자들의 사건관련전위 데이터를 이용하여 부트스트랩 분석을 수행하였다. 개개 피험자들의 세 가지 자극 유형(목표자극, 탐침자극, 무관련자극)에 대한 두정중심영역(Pz) 혹은 전두중심영역(Fz)에서의 모든 시행의 사건관련전위 진폭값이 분석에 이용되었다. 목표자극은 유죄지식을 포함하지 않는 실험과제와 관련된 자극으로, 모든 피험자는 실험과제에서 목표자극과 목표자극이 아닌 자극을 분류하도록 지시받았다. 탐침자극은 유죄지식을 포함한 자극으로, 무관련자극은 유죄지식을 포함하지 않는 실험과제와 관련이 없는 자극으로 구성되었다. 부트스트랩 분석은 BCD법과 BAD법으로 나뉘어 실시하였다. BCD법은 목표자극과 탐침자극의 사건관련전위 사이의 상관이 탐침자극과 무관련자극의 사건관련전위 사이의 상관보다 큰지를 계산하는 방법이며, BAD법은 탐침자극의 P300 진폭이 무관련자극의 P300 진폭보다 큰지를 계산하여 한 피험자의 유/무죄 여부를 가려내는 방법이다. 부트스트랩 분석 결과 판정불능을 제외한 BCD법의 탐지정확률은 최대 80.0%, 판정불능을 제외한 BAD법의 탐지정확률은 최대 56.5%로 BCD법의 탐지정확률이 더 높게 나타났다. 본 연구에서는 탐지정확률을 계산하는 방법 중 BAD법보다 BCD법이 더 효율적인 방법으로 나타났다.

Abstract

We compared detection accuracies of P300-based guilty knowledge test based on 2 bootstrap approaches: bootstrapped correlation difference (BCD) and bootstrapped amplitude difference (BAD). Event-related potential data of the guilty group (n=12) and the innocent group (n=12) in Kang and Kim(2010)'s study were subjected to bootstrap analysis. P300 amplitude from all single sweeps of each of target, probe, and irrelevant stimulus at the parietal midline (Pz) or the frontal midline (Fz) electrode site was collected for each participant. Target stimulus is relevant to the experimental task, but not related to the crime. Participants were asked to discriminate the target stimulus from other stimuli. Probe stimulus includes the critical information of the crime, the guilty knowledge, thus guilty participants are supposed to pay attention to it compared to irrelevant stimulus. Irrelevant stimulus is not relevant to the crime and the task. Two different bootstrap analysis were applied to determine individual's guilt or innocence. BCD method estimated double-centered correlation coefficients between the average of target and probe sweeps, and between the average of probe and irrelevant sweeps for a participant. If the former are greater than the latter in 600 trials out of 1,000 bootstrap iterations, the participant is regarded as guilty. BAD method estimated amplitude difference between probe and irrelevant sweeps, and if the difference is positive, the participant is found to be guilty. As a result, BCD method outperformed BAD method. The detection accuracies, without indeterminacy, of BCD and BAD were up to 80.0%, 56.5%, respectively. It seems that BCD method is more appropriate to determine individual's guilt or innocence, and to get high detection accuracy of the guilty knowledge test using event-related potentials.

초록

사람들이 예측을 할 때 어떤 정보를 이용할까? 인과 베이즈 모형은 인과 구조의 제약인 마크로프 원리에 의해 인과 예측이 이루어진다고 주장한다. 하지만, 선행 연구들은 사람들이 마르코프 원리가 제안하는 차단 규칙을 일관되게 위반하고 있음을 보고하고 있으며, 이는 인과 베이즈 모형의 심리적 실재성을 위협하는 것이다. 본 연구는 사람들이 어떻게 인과추론을 하는지 3가지 가설, 불충분 인과모형 가설, 모순가설(Walsh & Sloman, 2004), 그리고 기저 메커니즘 가설(Rehder & Burnett, 2005)을 검증하였다. 실험 1은 인과 충분성이 보장된 인과 구조에서도 차단 규칙은 위반됨을 보여주었으며, 이는 모순 가설(Walsh & Sloman, 2004)을 지지하는 결과이다. 실험 2는 실험 1에서 발생 가능한 혼입 변인을 통제하였다. 하지만 그 결과는 실험 1과 동일하였다. 실험 1과 실험 2의 결과가 인과 베이즈 모형에 시사하는 바를 논의하였다.

Abstract

What kind of information do people use to make predictions? The principle that causal Bayes nets suggest is that people follow structural constraints like the Markov principle. Previous studies have cast doubt on the psychological validity of the screening-off principle. I tested three hypotheses about how people used causal information to make predictions. Experiment 1 revealed that people violated the screening-off rule even when a causal structure was causally sufficient supporting the contradiction hypothesis (Walsh and Sloman, 2004). Experiment 2 controlled possible compounding in Experiment 1 but still reported the violation. Possible implications to the causal Bayes net formalism were discussed.

초록

Abstract

Fear conditioning, in which a neutral conditioned stimulus (CS) is contingently paired with an aversive unconditioned stimulus (US) and acquires capacity to elicit conditioned response (CR), has been studied extensively to elucidate neural substrate of associative memory. It has been shown that the critical change for the fear memory is stored as a form of modified synaptic response in the lateral nucleus (LA) of the amygdala. On the other hand, extinction, in which the fear CR is reduced as a result of repeated exposure to the CS without the US, has been known to depend on the infralimbic cortex (IL) of the medial prefrontal cortex. However, little is known about the interaction between the IL and LA over the course of extinction process. In the current study, we investigated the synaptic changes in the IL-LA pathway by measuring evoked field potentials (EFPs) before and after fear extinction. Following fear conditioning in which the rats were presented with five parings of the CS and footshock US, they were subjected to two extinction sessions composed of 10 CS-only trials each. In addition, they received a retention test composed of three CS-only presentations. To measure synaptic plasticity, evoked field potentials (EFPs) were recorded in the lateral nucleus of the amygdala (LA) by stimulating the IL, six hours after every session. The recorded EFP was significantly increased after the first extinction but not after the subsequent sessions. These data indicate that dynamic regulation of IL-LA synaptic efficacy underlies the suppression of conditioned fear response following extinction and suggest that consolidation of memory extinction involves changes in other synapses than IL-LA pathway.