Yonsei University · Neuroscience
Professor Sang Chul Chong's research lab specializes in visual perception, with a focus on how the human visual system processes and represents complex visual information. The lab investigates core mechanisms such as ensemble perception—where the visual system summarizes groups of similar objects into statistical representations like mean size or numerosity—and how attention modulates these processes. Key research directions include the interplay between selective attention and perceptual grouping, the role of spatial clustering in improving ensemble representation, and the neural and cognitive underpinnings of number sense and visual statistics. The lab combines behavioral experiments with innovative task designs to uncover how attention and perceptual organization shape our perception of visual ensembles and quantities.
Figures are computed from collected data and may differ slightly.
We investigated the effects of attention on dominance durations during binocular rivalry. In a series of three experiments, observers performed several tasks while viewing rival stimuli to ensure and control deployment of attention. We found that endogenous attention can prolong dominance durations of attended stimulus. We developed a novel single-task procedure where observer's responses in an attentional task were used to objectively estimate dominance durations of the attended stimulus. Using
In everyday scenes, objects rarely appear in isolation. Clustered objects in a scene are less readily identified than objects in isolation. We form a summary representation of the group as a whole. What properties characterize this summary? Likely candidates are statistical descriptors including the mean, the range and the variance. Understanding how these statistics are extracted is one goal for the study of perception. In a series of experiments, we investigated the accuracy of judgments of th
Visual environments often contain multiple elements, some of which are similar to one another or spatially grouped together. In the current study we investigated how one can use perceptual groups in representing ensemble features of the groups. In experiment 1 we found that participants' performance improved when items were easily segmented by a grouping cue based on proximity, suggesting that spatial grouping facilitates extracting and remembering ensemble representations from visual arrays con
The current study investigated whether attentional mechanisms operate on ensembles as higher-order units for selection. In Experiment 1, we presented sets of circles and asked participants to compare the mean sizes of the sets while concurrently detecting a small probe appearing at a centroid of one of the sets. We found that, both with and even without the task instruction to favour larger mean sizes, people's mean size judgement was more accurate for the sets with larger mean sizes. In additio
Quantity or numerosity is one of the basic properties of our environment. Humans and animals both have the neural representation of quantity or 'number sense'. The ability to extract and to manipulate numbers is closely related to our various cognitive functions such as the capacity of working memory, mathematical achievement, and texture perception. Evidence shows that the sense of number is not a unitary mechanism but rather a composition of two distinct processes; enumeration and estimation.
For efficient use of limited capacity, the visual system summarizes redundant information and prioritizes relevant information, strategies known respectively as <i>ensemble perception</i> and <i>selective attention</i>. Although previous studies showed a close relationship between these strategies, the specific mechanisms underlying the relationship have not been determined. We investigated how attention modulated mean-size computation. Fourteen people participated in this study. We hypothesized
Previous studies have shown that the visual system is able to estimate properties such as area, numerosity, and mean size efficiently and accurately. In the current study, we investigated whether our percepts of each of them could be based on ratios of the other two of these three properties. In each trial, observers viewed a display containing various quantities of filled circles and judged whether the magnitude of a property of the display, such as summed area, numerosity, or average size of t
Open papers in the app to read, cite, and organize with AI.
