Abstract
It is now clear that most animals, including humans, possess an ability to rapidly estimate number. Some have questioned whether this ability arises from dedicated numerosity mechanisms, or is derived indirectly from judgements of density or other attributes. We describe a series of psychophysical experiments, largely using adaptation techniques, which demonstrate clearly the existence of a number sense in humans. The number sense is truly general, extending over space, time and sensory modality, and is closely linked with action. We further show that when multiple cues are present, numerosity emerges as the natural dimension for discrimination. However, when element density increases past a certain level, the elements become too crowded to parse, and the scene is perceived as a texture rather than array of elements. The two different regimes are psychophysically discriminable in that they follow distinct psychophysical laws, and show different dependencies on eccentricity, luminance levels and effects of perceptual grouping. The distinction is important, as the ability to discriminate numerosity, but not texture, correlates with formal maths skills.This article is part of the discussion meeting issue ‘The origins of numerical abilities’.
Highlights
Humans may be the only species with a linguistically mediated code for numbers, we share an approximate, non-verbal representation of number with many animal species, as many papers in this special issue make amply clear
The human psychophysical results presented here clearly reinforce the animal studies demonstrating the existence of a system dedicated to the perception of numerosity, the number of objects within a particular field of view
This system seems to be quite independent of mechanisms dedicated to texture perception, but is closely connected with systems for estimating the numerosity of sequences of events, in any sensory modality, and with the production of actions
Summary
Humans may be the only species with a linguistically mediated code for numbers, we share an approximate, non-verbal representation of number with many animal species, as many papers in this special issue make amply clear. The evolutionary advantage of this capacity is obvious, facilitating choice of areas with more food, and/or more conspecies, and allowing quick determination of which group of competitors is more numerous. How is numerosity sensed—directly, by a number sense, as suggested by the physiological and behavioural studies in many species [1,2,3,4,5,6], or indirectly via other means, such as estimating texture density [7,8,9,10,11,12]? What are the limits of the number sense? How is numerosity sensed—directly, by a number sense, as suggested by the physiological and behavioural studies in many species [1,2,3,4,5,6], or indirectly via other means, such as estimating texture density [7,8,9,10,11,12]? What are the limits of the number sense?
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Philosophical Transactions of the Royal Society B: Biological Sciences
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
