A common visual metric for approximate number and density
Open Access
- 21 November 2011
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 108 (49), 19552-19557
- https://doi.org/10.1073/pnas.1113195108
Abstract
There is considerable interest in how humans estimate the number of objects in a scene in the context of an extensive literature on how we estimate the density (i.e., spacing) of objects. Here, we show that our sense of number and our sense of density are intertwined. Presented with two patches, observers found it more difficult to spot differences in either density or numerosity when those patches were mismatched in overall size, and their errors were consistent with larger patches appearing both denser and more numerous. We propose that density is estimated using the relative response of mechanisms tuned to low and high spatial frequencies (SFs), because energy at high SFs is largely determined by the number of objects, whereas low SF energy depends more on the area occupied by elements. This measure is biased by overall stimulus size in the same way as human observers, and by estimating number using the same measure scaled by relative stimulus size, we can explain all of our results. This model is a simple, biologically plausible common metric for perceptual number and density.Keywords
This publication has 33 references indexed in Scilit:
- Effect of the luminance signal on adaptation-based time compressionJournal of Vision, 2011
- Observers Exploit Stochastic Models of Sensory Change to Help Judge the Passage of TimeCurrent Biology, 2011
- How might the discrepancy in the effects of perceptual variables on numerosity judgment be reconciled?Attention, Perception, & Psychophysics, 2010
- Number estimation relies on a set of segmented objectsCognition, 2009
- Connectedness affects dot numerosity judgment: Implications for configural processingPsychonomic Bulletin & Review, 2009
- How Humans Count: Numerosity and the Parietal CortexThe Neuroscientist, 2009
- Modulating Attentional Load Affects Numerosity Estimation: Evidence against a Pre-Attentive Subitizing MechanismPLOS ONE, 2008
- Monotonic Coding of Numerosity in Macaque Lateral Intraparietal AreaPLoS Biology, 2007
- Sometimes area counts more than numberProceedings of the National Academy of Sciences of the United States of America, 2006
- Representation of the Quantity of Visual Items in the Primate Prefrontal CortexScience, 2002