Abstract
How does the spatial organization of objects affect their perceived numerosity? Previous studies have demonstrated that when simple, homogenous stimuli (dots), are presented in a regular configuration, they are judged to be more numerous than when presented in a random configuration (Ginsburg, 1978). However, such homogeneous stimuli are highly conducive to perceptual organization principles, such as grouping, that may not apply to real-word objects. In the current study, we examined the role of spatial organization of real-world scenes made up of everyday objects. Stimuli consisted of photographs of 40 different collections of between 11 and 32 office items (e.g. stapler, computer mouse, etc.) arranged on a desk. Each collection was used to generate two stimuli, one with the objects arranged in an organized manner and one in a disorganized manner (80 trials total). Both the organized and disorganized versions of each collection contained the same objects, centered on the same spatial locations; however in the organized condition the individual orientations of the items were parallel with each other and the contours of the desk while in the disorganized condition they were in random orientations. Each scene was presented for 500 msec. after which the participant guessed the number of items in the scene. While overall accuracy (i.e. measured as difference from actual numerosity) was similar across conditions, we found that that disorganized collections were judged as having more objects than organized collections. Thus, spatial organization produces an opposite effect in patterns of simple homogenous stimuli—where it leads to a perception of lower numerosity—and real-world scenes—where it leads to a perception of higher numerosity. This difference may depend on the subjective sense that disorganized configurations of real-world objects are 'cluttered', relative to typical/preferred organizations, leading to higher perceived numeorsity.
Meeting abstract presented at VSS 2014