Rapid enumeration within a fraction of a single glance: The role of visible persistence in object individuation capacity

Abstract

The number of items that can be individuated at a single glance is limited. Here, we investigate object individuation at a higher temporal resolution, in fractions of a single glance. In two experiments involving object individuation we manipulated the duration of visual persistence of the target items with a forward masking procedure. The number of items as well as their stimulus–onset asynchrony (SOA) to the mask was varied independently. The results showed main effects of numerosity and SOA, as well as an interaction. These effects were not caused by a generic reduction of item visibility by the mask. Instead, the SOA manipulation appeared to fractionate the time to access the sensory image. These findings suggest that the capacity limit of 3–4 items found in object individuation is, at least partially, the consequence of the temporal window of access to sensory information.

Keywords:

• Capacity
• Object individuation
• Sensory memory
• Subitizing
• Visible persistence

Acknowledgements

The research was supported in part by the Italian Ministry of Universities and Research (MIUR) project PRIN 2009 and by the Fondazione Cassa di Risparmio di Trento e Rovereto.