Right hemisphere superiority for subitising

Abstract

Lateral differences in the enumeration of small sets of items (i.e., between two and five) were investigated in a normal adult sample. Confounds due to stimulus repetition, which have characterised previous subitising research, were eliminated in a task involving the presentation of purely random item arrays to the left and right visual fields. The results indicated a clear left visual field advantage for the enumeration of arrays containing three to four items. This finding is consistent with the widely held view that the subitising process is used to enumerate arrays of up to four items, and calls into question Butterworth's (1999) recent claim that subitising is a left hemisphere process. The implications for previous pattern recognition and visual process accounts of this ability are considered.