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The measurement of approximate number system acuity across the lifespan is compromised by congruency effects

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posted on 14.05.2018, 13:38 by Jade E. Norris, Sarah Clayton, Camilla GilmoreCamilla Gilmore, Matthew InglisMatthew Inglis, Julie Castronovo
Recent studies have highlighted the influence of visual cues such as dot size and cumulative surface area on the measurement of the approximate number system (ANS). Previous studies assessing ANS acuity in ageing have all applied stimuli generated by the Panamath protocol, which does not control nor measure the influence of convex hull. Crucially, convex hull has recently been identified as an influential visual cue present in dot arrays, with its impact on older adults’ ANS acuity yet to be investigated. The current study therefore investigated the manipulation of convex hull by the Panamath protocol, and its effect on the measurement of ANS acuity in younger and older participants. Firstly, analyses of the stimuli generated by Panamath revealed a confound between numerosity ratio and convex hull ratio. Secondly, although older adults were somewhat less accurate than younger adults on convex hull incongruent trials, ANS acuity was broadly similar between the groups. These findings have implications for the valid measurement of ANS acuity across all ages, and suggest that the Panamath protocol produces stimuli that do not adequately control for the influence of convex hull on numerosity discrimination.



  • Science


  • Mathematical Sciences

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Quarterly Journal of Experimental Psychology


NORRIS, J.E. ... et al, 2018. The measurement of approximate number system acuity across the lifespan is compromised by congruency effects. Quarterly Journal of Experimental Psychology, 72 (5), pp.1037-1046.


SAGE Publications © Experimental Psychology Society


AM (Accepted Manuscript)

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This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

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This paper was published in the journal Quarterly Journal of Experimental Psychology and the definitive published version is available at https://doi.org/10.1177/1747021818779020.