Investigating perceptual grouping by common region through a repetition discrimination task

Visual perception is critical in helping people understand and infer states of the world in which they live. The Gestalt law of common region describes how elements belonging in the same region tend to be perceptually grouped together pre-attentively. An important feat in vision is the ability to organize an unstructured world into more coherent groups of objects. Recent evidence suggests that perceptual grouping occurs not only from visual similarity, but also from associative similarity. More specifically, visually dissimilar shapes are perceptually grouped if they have a learned association. This study investigated how effectively perceptual grouping can form through visual statistical learning. Participants performed a repetition discrimination task (RDT), a type of visual task, on the computer and responded with keyboard presses. Standard perceptual grouping was found in the training phase as participants had significantly faster discrimination times when the target shapes in the visual search row were grouped by common region (within-group condition) compared to shapes from an equidistant but different region (between-group condition). The perceptual grouping effect did not replicate in a transfer phase, where common region grouping was removed but shape associations remained. Finally, there were no significant differences in discrimination time between within-group and between-group conditions. This study showed that grouping of objects through visual cues did not lead to strong learning of associative similarity.