Past Issues

Attentional blink is observed in an identification task of multiple targets during rapid serial visual presentation (RSVP) where performance for the second target (T2) that follows within 500ms of the first (T1) shows systematic decrease although that for T1 remains highly accurate. Theories accounting for attentional blink can be classified into two broad categories of resource depletion model and disruption of input filter model. Meanwhile, visual attention capacity shows hemifield independence between left and right visual fields, and many studies reported bilateral advantage in a range of visual working memory tasks. The current research tested two major theories of attentional blink using bilateral independence of attentional capacity. To this end, we conducted two experiments where two RSVPs were presented in either bilateral or unilateral visual fields. Experiment 1 presented two RSVPs which contained both T1 and T2 in either bilateral or unilateral visual fields and tested interaction between attentional blink and bilateral advantage. Experiment 2 removed T1 in one of the two RSVPs to test whether attentional blink obtains when identification of T1 and T2 utilize independent sources of attention across two visual fields. The results showed that subjects were more accurate when two RSVPs were presented in bilateral visual fields (i.e., bilateral advantage) although there was no interaction between attentional blink and bilateral advantage (Experiment 1). In addition, attentional blink for T2 was observed in a T1-absent RSVP even when two RSVPs were presented in bilateral visual fields (Experiment 2). These results support disruption of input filter model rather than resource depletion model.

keyword : Attentional Blink, Attentional Resources, Hemifield Independence, Bilateral Field Advantage, 주의 깜빡임, 주의 자원, 좌우시야 독립성, 양측영역 이득

The present study examined the effect of stimulus contrast and color on detection of a target embedded in streams of letters. In Experiment 1, each trial displayed four rapid serial visual presentation (RSVP) streams of letters (i.e., multi-RSVP), and each stream occupied one of four different locations. Each frame in the RSVP stream had four white distractors at the locations except one frame where a dim grey target was displayed at a location with three white distractors at the remaining locations. In the low-visibility target condition, the target`s grey color was slightly darker than the background grey whereas much dimmer in the high-visibility condition. Participants were asked to report presence of a predesignated target as quickly and accurately as possible upon its detection in each trial, and their target detection turned out more accurate and quicker in the high-visibility than the low-visibility condition. In Experiment 2, the same RSVP displays and task as Experiment were used, but the grey target letters in the high-visibility condition were replaced with those of distinct chromatic colors. Participants detected target presence more accurately in the high-visibility condition, but the reaction time did not differ between the visibility conditions. The results indicate that higher stimulus contrast as well as distinct color can improve perception of a target stimulus displayed among visually-demanding background, but also suggest that stimulus contrast may play a more substantial role for such perceptual improvement.

keyword : Stimulus Contrast, Color, RSVP, Visibility, Target Detection, 자극명암대비, 색상, 신속순차제시, 가시성, 표적 탐지

In hypothesis testing, the interpretation of a statistic obtained from the data analysis relies on a probabilistic distribution of the statistic constructed according to several statistical theories. For instance, the statistical significance of a mean difference between experimental conditions is determined according to a probabilistic distribution of the mean differences (e.g., Student`s t) constructed under several theoretical assumptions for population characteristics. The present study explored the logic and advantages of random-resampling approach for analyzing event-related potentials (ERPs) where a hypothesis is tested according to the distribution of empirical statistics that is constructed based on randomly resampled dataset of real measures rather than a theoretical distribution of the statistics. To motivate ERP researchers` understanding of the random-resampling approach, the present study further introduced a specific example of data analyses where a random-permutation procedure was applied according to the random-resampling principle, as well as discussing several cautions ahead of its practical application to ERP data analyses.

keyword : Hypothesis Testing, Random Resampling, Empirical Statistics, ERP Data Analyses, 가설 검증, 무선재추출, 경험적 통계치, ERP 자료 분석

Emotion affects many parts of human life such as learning ability, behavior and judgment. It is important to understand human nature. Emotion can only be inferred from facial expressions or gestures, what it actually is. In particular, emotion is difficult to classify not only because individuals feel differently about emotion but also because visually induced emotion does not sustain during whole testing period. To solve the problem, we acquired bio-signals and extracted features from those signals, which offer objective information about emotion stimulus. The emotion pattern classifier was composed of unsupervised learning algorithm with hidden nodes and feature vectors. Restricted Boltzmann machine (RBM) based on probability estimation was used in the unsupervised learning and maps emotion features to transformed dimensions. The emotion was characterized by non-linear classifiers with hidden nodes of a multi layer neural network, named deep belief network (DBN). The accuracy of DBN (about 94 %) was better than that of back-propagation neural network (about 40 %). The DBN showed good performance as the emotion pattern classifier.

keyword : Emotion, Biological Signal, Restricted Boltzmann Machine (RBM), Multilayer Neural Network (MNN), Deep Belief Network (DBN), 감정, 생체신호

`Smart Sensibility Mat (SSM)` was developed and manufactured for positive sensibility of newborn with fiber, digital, and sensibility technology to reflect features and advantages of kangaroo care. For tactile stimuli, the tube of the silicon material to provide a constant temperature of 32℃ was inserted into the mat and connected to the water-thermostat. To provide a uniform temperature throughout the mat, the fabric by the inserting conductive yarn was attached to the mat surface. After wrapping the mat with cotton pad, the polyurethane foam used as medicine in order to similar to the human skin was bonded to the surface of the mat. To provide the auditory stimuli of a level of 30dB with mother`s heartbeat sounds and voice recorded in advance, the Bluetooth speaker was inserted into the mat. To investigate the effects of SSM, 10 newborns who born within two weeks were involved in this experiment. While the baby was lying on each of the general mat (GM) and SSM, the baby`s physiological signals-heart rate, breathing rate, temperature- were measured and then, those were conducted t-test to examine the difference between the signals of SSM and GM. The results were as follows: heart rate (t=8.131, p<.001) and respiratory rate (t=7.227, p<.001) among the physiological signals of SSM decreased significantly than GM within the normal range. Temperature (t=1.062, p=0.292) at SSM showed a tendency to decrease than GM within the normal range. This means the tactile stimuli and the auditory stimuli providing from SSM give stable physiological responses. Thus, SSM leads to have psychological comfort and stability of newborns.

keyword : Kangaroo care, Newborn, Sensibility, Smart Sensibility Mat, Physiological Signal, Psychological Comfort, 캥거루 케어, 신생아, 감성, 스마트 성 매트, 생리신호, 심리적 안정