The role of attention in subitizing: Is the magical number 1?

Abstract

Abstract Subitizing, the fast and accurate enumeration of up to about 3 or 4 objects, has often been thought to be dependent on limited-capacity preattentive mechanisms. We used an attentional blink paradigm to investigate the extent to which subitizing requires attentional resources. On each trial, subjects identified a target letter in an RSVP stream and then enumerated dots presented in the stream that were either simultaneous with the target letter or followed it by up to 400 ms. For numerosities from 2 to 9, evidence of an attentional blink was observed; only enumeration of 0 or 1 elements was independent of lag. Thus, even enumeration of 2–3 objects, which is within the traditional subitizing range, appears to require attentional resources. The relation of this work to studies on the attentional requirements of detecting a unique item among distractors, a supposedly preattentive discrimination, is briefly discussed. Acknowledgements We would like to thank our research assistants Kevin Dieter and Loandra Torres for their contributions, and Chris Olivers and Derrick Watson for their cooperation. Also, we appreciate helpful comments from James Brockmole, Vince Di Lollo, Robert Gordon, and John Henderson. Preliminary data were presented at the 2006 Vision Sciences Society Conference in Sarasota, FL, USA.