Gilmore-et-al-20445911.2016.1221828.pdf (1.06 MB)
Download file

Congruency effects in dot comparison tasks: convex hull is more important than dot area

Download (1.06 MB)
journal contribution
posted on 07.09.2016, 08:40 by Camilla GilmoreCamilla Gilmore, Lucy Cragg, Grace Hogan, Matthew InglisMatthew Inglis
The dot comparison task, in which participants select the more numerous of two dot arrays, has become the predominant method of assessing Approximate Number System (ANS) acuity. Creation of the dot arrays requires the manipulation of visual characteristics, such as dot size and convex hull. For the task to provide a valid measure of ANS acuity, participants must ignore these characteristics and respond on the basis of number. Here, we report two experiments that explore the influence of dot area and convex hull on participants’ accuracy on dot comparison tasks. We found that individuals’ ability to ignore dot area information increases with age and display time. However, the influence of convex hull information remains stable across development and with additional time. This suggests that convex hull information is more difficult to inhibit when making judgements about numerosity and therefore it is crucial to control this when creating dot comparison tasks.


This work was funded by a grant (RES-062-23-3280) from the Economic and Social Research Council, UK (CG and LC), a Royal Society Dorothy Hodgkin Research Fellowship (CG) and a Royal Society Worshipful Company of Actuaries Research Fellowship (MI).



  • Science


  • Mathematics Education Centre

Published in

Journal of Cognitive Psychology


GILMORE, C. ... et al., 2016. Congruency effects in dot comparison tasks: convex hull is more important than dot area. Journal of Cognitive Psychology, 28 (8), pp.923-931


Informa UK (© the authors)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at:

Acceptance date


Publication date



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 work is properly cited.





Usage metrics