Grouping strategies in induced perceptual grouping

Induced grouping refers to the influence of a perceived group of elements on the grouping of another set of elements that cannot be explained by other grouping principles. Vickery (2008) first highlighted this phenomenon and, despite convincing demonstrations of this principle, seems to be the only direct study. Here we report two successful large sample replications of one of Vickery's experiments. We also explain Vickery's results with a cortical model of visual grouping and selection. We extended a previous model, so that it performs a feature-based search of an image for a target. We show that induced grouping effects are the result of a connection strategy that links together target pairs in a visual search task combined with a selection strategy that tends to place a selection signal at locations close to the target pair features. These strategies interact because the connection strategy that links target pairs also sometimes links inducing elements, thereby influencing the selection signal location. The model extension plays a key role in explaining this phenomenon and enables the model to simulate other tasks, like visual search, where the observer uses a dynamic and feature-guided selection process.