Abstract
The mechanisms that subserve mid-level attentional processes in adults have been implicated in infant object representation. One theoretical issue in both literatures concerns what entities can be attended, indexed, and traced through space and time. The theory of object-based attention states that objects are privileged in this mid-level system. Previous work with adults (Scholl & vanMarle, 2003) and infants has provided evidence that entity tracking is disrupted by non-cohesion. Huntley-Fenner et al. (2002) and Chiang & Wynn (2000) have shown that 8- and 12-month old infants cannot trace the numerical identity of non-cohesive entities through occlusion. But theories of adult attention propose that attention can also be assigned to locations, or to perceptual features, suggesting that infants may be able to index distinct portions of non-cohesive entities if no tracking of individuals through time and/or occlusion is required. In the present study, 40 8-month-old infants were habituated to displays of either one or two portions of sand poured onto a stage, or to one or two perceptually similar solid piles lowered by a string onto a stage, and their looking time to the familiar vs. novel number of entities (once they were at rest on the stage floor) was measured. Infants did not distinguish one from two portions of sand; in contrast, they easily differentiated one from two solid objects. These results provide strong evidence for object-based attentional processes in infancy, with perhaps even stronger constraints on attentional selection than in adulthood. Objects (bounded, cohesive wholes) attracted indexes, whereas non-objects did not.