Modulating attentional load affects numerosity estimation: evidence against a pre-attentive subitizing mechanism

Vetter, P., Butterworth, B. and Bahrami, B. (2008) Modulating attentional load affects numerosity estimation: evidence against a pre-attentive subitizing mechanism. PLoS ONE, 3(9), e3269. (doi: 10.1371/journal.pone.0003269) (PMID:18813345) (PMCID:PMC2533400)

Abstract

Traditionally, the visual enumeration of a small number of items (1 to about 4), referred to as subitizing, has been thought of as a parallel and pre-attentive process and functionally different from the serial attentive enumeration of larger numerosities. We tested this hypothesis by employing a dual task paradigm that systematically manipulated the attentional resources available to an enumeration task. Enumeration accuracy for small numerosities was severely decreased as more attentional resources were taken away from the numerical task, challenging the traditionally held notion of subitizing as a pre-attentive, capacity-independent process. Judgement of larger numerosities was also affected by dual task conditions and attentional load. These results challenge the proposal that small numerosities are enumerated by a mechanism separate from large numerosities and support the idea of a single, attention-demanding enumeration mechanism.

• Item Type: Articles
• Additional Information: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Vetter, Dr Petra
• Authors: Vetter, P., Butterworth, B., and Bahrami, B.
• College/School: College of Science and Engineering > School of Psychology
• Journal Name: PLoS ONE
• Publisher: Public Library of Science
• ISSN: 1932-6203
• ISSN (Online): 1932-6203
• Published Online: 01 January 2008
• Copyright Holders: © 2008 Vetter et al
• First Published: First published in PLoS ONE 2008 3(9): e3269
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher