Numerosity and cumulative surface area are perceived holistically as integral dimensions

Area of Science:

• Cognitive Psychology
• Perception
• Numerical Cognition

Background:

• The dominant theory suggests numerosity perception relies on an abstract code, separate from non-numerical visual features.
• This abstract numerosity code is believed to be uncontaminated by other visual information, such as object size or density.

Purpose of the Study:

• To investigate whether number and cumulative surface area are processed as integral or separable dimensions in visual perception.
• To challenge the dominant view of an abstract numerosity code by examining the holistic perception of quantity and area.

Main Methods:

• Two experiments assessed perceived similarity of dot arrays varying in number and cumulative area.
• Stimulus space modeling using Euclidean and city-block distances compared holistic versus separable dimension perception.
• Models controlled for other magnitude properties like density and image similarity.

Main Results:

• Perceived similarity was best modeled by Euclidean distance, indicating holistic processing of number and cumulative area.
• This pattern is comparable to other integral dimensions (e.g., brightness/saturation) but distinct from separable dimensions (e.g., shape/color).
• Euclidean distance remained the superior model even after controlling for confounding factors like density.

Conclusions:

• Numerosity perception involves the obligatory processing of non-numerical magnitude, specifically cumulative surface area.
• These findings contradict the dominant view of an abstract, uncontaminated numerosity code.
• Visual number perception is not purely abstract but is intertwined with the perception of other visual magnitudes.