Article

Subitizing reflects visuo-spatial object individuation capacity

Center for Mind/Brain Sciences, University of Trento, Italy.
Cognition (Impact Factor: 3.63). 06/2011; 121(1):147-53. DOI: 10.1016/j.cognition.2011.05.007
Source: PubMed

ABSTRACT

Subitizing is the immediate apprehension of the exact number of items in small sets. Despite more than a 100years of research around this phenomenon, its nature and origin are still unknown. One view posits that it reflects a number estimation process common for small and large sets, which precision decreases as the number of items increases, according to Weber's law. Another view proposes that it reflects a non-numerical mechanism of visual indexing of multiple objects in parallel that is limited in capacity. In a previous research we have gathered evidence against the Weberian estimation hypothesis. Here we provide first direct evidence for the alternative object indexing hypothesis, and show that subitizing reflects a domain general mechanism shared with other tasks that require multiple object individuation.

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Available from: David Melcher, Feb 06, 2014
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    • "Recently, visual subitizing has been shown to be strongly related to visual working memory capacity (Piazza et al., 2011). Interestingly, loading working memory impairs estimation precision in the subitizing range but not in the numerosity estimation range (N > 4). "
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    ABSTRACT: Although humans are the only species to possess language-driven abstract mathematical capacities, we share with many other animals a nonverbal capacity for estimating quantities or numerosity. For some time, researchers have clearly differentiated between small numbers of items-less than about four-referred to as the subitizing range, and larger numbers, where counting or estimation is required. In this review, we examine more recent evidence suggesting a further division, between sets of items greater than the subitizing range, but sparse enough to be individuated as single items; and densely packed stimuli, where they crowd each other into what is better considered as a texture. These two different regimes are psychophysically discriminable in that they follow distinct psychophysical laws and show different dependencies on eccentricity and on luminance levels. But provided the elements are not too crowded (less than about two items per square degree in central vision, less in the periphery), there is little evidence that estimation of numerosity depends on mechanisms responsive to texture. The distinction is important, as the ability to discriminate numerosity, but not texture, correlates with formal maths skills.
    Full-text · Article · Sep 2015 · Perception
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    • "Thus, it may be possible that both visual memory for objects and enumeration share a common resource with similar capacity limitations and variations that correlate between subjects (Cutini & Bonato, 2012; Piazza et al., 2011). This has been hypothesized to result from an initial competitive process of the individuation of the objects present in a visual scene (Melcher & Piazza, 2011). "

    Full-text · Dataset · Jul 2015
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    • "Thus, it may be possible that both visual memory for objects and enumeration share a common resource with similar capacity limitations and variations that correlate between subjects (Cutini & Bonato, 2012; Piazza et al., 2011). This has been hypothesized to result from an initial competitive process of the individuation of the objects present in a visual scene (Melcher & Piazza, 2011). "

    Full-text · Dataset · Jul 2015
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