Putting Figure-Ground and Grouping into Context

Animated Display Examples

by Joseph L. Brooks and Jon Driver

Institute of Cognitive Neuroscience, University College London

Edge and Region Grouped Condition

The lower section (below the red occluder) is the locally-biased section. Palmer & Brooks' Edge-Region Grouping cue is used to assign the edge in this section to the left, black region. The lower section's edge moves in common fate with the edge of the upper section. This is an example of edge-grouping. This display also contains region grouping because the regions in both sections of the display are the same color. Our results indicate that participants assign the edge of the upper locally-unbiased section to the left up to 80% of the time in this condition. This is significantly different than no preference in the direction of assigning the edge (50%) and thus suggests a bias from the context that is dependent on edge and region grouping between the two sections.***The exact speed of the animation will depend on your computer. In the experiments the edges oscillated at either 1.0 Hz or 1.5 Hz.

Edge-Only Grouped Condition

In the following example, edge-grouping is present but region grouping is not present because the regions in the biased and unbiased sections are different colors. Our experiments show that participants are significantly influence by the biased context when they make judgments about the locally-unbiased section (upper section here). However, the effect is weaker than when both edge and region grouping are both present (example above).

Region-Only Grouped Condition

In the following example the edges in the biased and locally-unbiased sections are NOT grouped. They move independently of one another. However, region grouping by color similarity is present. We found that in this condition, context-consistent judgments of the locally-unbiased section (upper section here) we not greater than 50% suggesting that region-grouping alone in the presence of strong evidence against edge-grouping is not sufficient for mediating the spread of figure-ground organization.

Ungrouped Condition

In the following example, neither edge-grouping or region-grouping are present. Context-consistent judgments in the locally-unbiased section (upper section here) were not different from 50%.