The color-sharing bonus: Roles of perceptual organization and attentive processes in visual working memory

Color repetitions in a visual scene boost working memory capacity for its elements, a phenomenon known as the color-sharing effect. This may occur because improved perceptual organization reduces information load or because the repetitions capture attention. The implications of these explanations differ drastically for both the theoretical meaning of this effect and its potential value for applications in design of visual materials. Previous research suggests that the color-sharing bonus is restricted to tests of the repeated colors themselves, which tends to support the idea that the repetitions capture attention, possibly to the exclusion of the remaining elements. We explicitly manipulated the availability of general attention during a visual change detection task by comparing groups of healthy young adults engaged in articulatory suppression or backward counting. We also tracked eye movements as an implicit indicator of selective attention. Estimated memory capacity was always higher when color duplicates were tested, and under full attention conditions this bonus spilled over to the unique colors too. Analyses of gazes showed that with full attention, participants tended to glance earlier at duplicate colors during stimulus presentation but prioritized looking at unique colors during the retention interval. This pattern of results suggests that the color-sharing bonus occurs due to efficient perceptual organization of the display, which might be enhanced by strategic attention allocation when attention is available.