Numerosity adaptation effect
Encyclopedia
The numerosity adaptation effect is a perceptual phenomenon
in numerical cognition
which demonstrates non-symbolic numerical intuition
and exemplifies how numerical percepts can impose themselves upon human brain automatically. This effect was first described in 2008.
Presently, this effect is described only for controlled experimental conditions. In the illustration, a viewer should have a strong impression that the left display (lower figure) is more numerous than the right, after 30 seconds of viewing the adaptation (upper figure), although both have exactly the same number of dots. The viewer might also underestimate the number of dots presented in the display.
Both effects are resistant to manipulation of the non-numerical parameters of the display. Thus, this effect cannot be simply explained in terms of size, density, or contrast.
Perhaps the most astonishing aspect of these effects is that they happen immediately, and without conscious control (i.e., knowing that the numbers are equal would not hamper their happening). This points to the operation of a special and largely automatic processing system. As noted by Burr & Ross (2008):
and that the results may be better explained in terms of texture density such that only dots falling within the spatial region where the test is displayed effectively adapt the region.
However, as the display in the original experiments was of spots uniformly either white or black, the kurtosis account is inapplicable. The texture density explanation doesn't seem to disentangle the complexity of these phenomena as in the display the left field adapts to many dots, the
right field to few, and these adapters selectively affect the relevant test stimuli. It is not the number of dots in the entire display that causes the adaptation but only those within a particular area. At present, why adaptation have such profound effect on numerosity estimates remains largely unexplained.
Perception
Perception is the process of attaining awareness or understanding of the environment by organizing and interpreting sensory information. All perception involves signals in the nervous system, which in turn result from physical stimulation of the sense organs...
in numerical cognition
Numerical cognition
Numerical cognition is a subdiscipline of cognitive science that studies the cognitive, developmental and neural bases of numbers and mathematics. As with many cognitive science endeavors, this is a highly interdisciplinary topic, and includes researchers in cognitive psychology, developmental...
which demonstrates non-symbolic numerical intuition
Number sense
In mathematics education, number sense can refer to "an intuitive understanding of numbers, their magnitude, relationships, and how they are affected by operations." Many other definitions exist, but are similar to the one given...
and exemplifies how numerical percepts can impose themselves upon human brain automatically. This effect was first described in 2008.
Presently, this effect is described only for controlled experimental conditions. In the illustration, a viewer should have a strong impression that the left display (lower figure) is more numerous than the right, after 30 seconds of viewing the adaptation (upper figure), although both have exactly the same number of dots. The viewer might also underestimate the number of dots presented in the display.
Both effects are resistant to manipulation of the non-numerical parameters of the display. Thus, this effect cannot be simply explained in terms of size, density, or contrast.
Perhaps the most astonishing aspect of these effects is that they happen immediately, and without conscious control (i.e., knowing that the numbers are equal would not hamper their happening). This points to the operation of a special and largely automatic processing system. As noted by Burr & Ross (2008):
Possible explanations
Few explanations were suggested to explain these phenomena. It was argued that they are heavily dependent on density and less on numerosity. Also, it was suggested that numerosity may be correlated with kurtosisKurtosis
In probability theory and statistics, kurtosis is any measure of the "peakedness" of the probability distribution of a real-valued random variable...
and that the results may be better explained in terms of texture density such that only dots falling within the spatial region where the test is displayed effectively adapt the region.
However, as the display in the original experiments was of spots uniformly either white or black, the kurtosis account is inapplicable. The texture density explanation doesn't seem to disentangle the complexity of these phenomena as in the display the left field adapts to many dots, the
right field to few, and these adapters selectively affect the relevant test stimuli. It is not the number of dots in the entire display that causes the adaptation but only those within a particular area. At present, why adaptation have such profound effect on numerosity estimates remains largely unexplained.
See also
- Approximate number systemApproximate number systemThe approximate number system is a hypothetical physiological basis for the intuitive "number sense". As its name suggests, it only provides an approximate sense of number, and is not an accurate symbolic computation system...
- Numerical cognitionNumerical cognitionNumerical cognition is a subdiscipline of cognitive science that studies the cognitive, developmental and neural bases of numbers and mathematics. As with many cognitive science endeavors, this is a highly interdisciplinary topic, and includes researchers in cognitive psychology, developmental...
- Number senseNumber senseIn mathematics education, number sense can refer to "an intuitive understanding of numbers, their magnitude, relationships, and how they are affected by operations." Many other definitions exist, but are similar to the one given...
- NumeracyNumeracyNumeracy is the ability to reason with numbers and other mathematical concepts. A numerically literate person can manage and respond to the mathematical demands of life...