August 2009
Volume 9, Issue 8
Vision Sciences Society Annual Meeting Abstract  |   August 2009
A visual sense of number
Author Affiliations
  • David Burr
    Dipartimento di Psicologia, Università Degli Studi di Firenze and Department of Psychology, University of Western Australia
Journal of Vision August 2009, Vol.9, 12. doi:
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      David Burr; A visual sense of number. Journal of Vision 2009;9(8):12.

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      © ARVO (1962-2015); The Authors (2016-present)

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Evidence exists for a non-verbal capacity to apprehend number, in humans (including infants), and in other primates. We investigated numerosity perception in adult humans, by measuring Weber fractions with a series of techniques, and by adaptation. The Weber fraction measurements suggest that number estimation and “subitizing” share common mechanisms. Adapting to large numbers of dots increased apparent numerosity (by a factor of 2–3), and adapting to small numbers increased it. The magnitude of adaptation depended primarily on the numerosity of the adapter, not on size, orientation or contrast of test or adapter, and occurred with very low adapter contrasts. Varying pixel density had no effect on adaptation, showing that it depended solely on numerosity, not related visual properties like texture density. We propose that just as we have a direct visual sense of the reddishness of half a dozen ripe cherries so we do of their sixishness. In other words there are distinct qualia for numerosity, as there are for colour, brightness and contrast, not reducible to spatial frequency or density of texture.

Burr, D. (2009). A visual sense of number [Abstract]. Journal of Vision, 9(8):12, 12a,, doi:10.1167/9.8.12. [CrossRef]

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