A visual sense of number

David Burr¹ & John Ross²

Correspondence: dave [at] in.pi.cnr.it

Correspondence: jr [at] psy.uwa.edu.au

1. Dipartimento di Psicologia, Universita' di Firenze, Italy
2. School of Psychology, The University of Western Australia

PDF (59.4 KB)

Document Type:

Manuscript

Date:

Received 20 November 2007 08:56 UTC; Posted 20 November 2007

Subjects:

Neuroscience

Tags:

• Vision
• perception
• numerosity
• adaptation

Abstract:

Evidence exists for a non-verbal capacity to apprehend number, in humans¹ (including infants^2,3) and in other primates^4-6. Here we show that perceived numerosity is susceptible to adaptation, along with primary visual properties of a scene like colour, contrast, size and speed. Apparent numerosity was decreased by adapting to large numbers of dots and increased by adapting to small numbers, the effect depended entirely on the numerosity of the adapter, not on contrast, size, orientation or pixel density, and occurred with very low adapter contrasts. We suggest that numerosity is also an independent primary visual property, not reducible to others like spatial frequency or density of texture⁷.

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