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Related Experiment Video

Updated: Jan 3, 2026

Development of a Gaze-Contingent Display Framework Designed for Perceptual and Oculomotor Research with Simulated Central Vision Loss

Development of a Gaze-Contingent Display Framework Designed for Perceptual and Oculomotor Research with Simulated Central Vision Loss

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Three-systems for visual numerosity: A single case study.

G Anobile¹, F Tomaiuolo², S Campana³

¹Department of Developmental Neuroscience, IRCCS Stella Maris Foundation, Pisa, Italy.

Neuropsychologia

|November 15, 2019

Summary

This summary is machine-generated.

Human numerosity perception relies on three distinct mechanisms. Neuropsychological study of a patient with simultanagnosia supports this, revealing deficits in low and high numerosity judgments but not intermediate ones.

Keywords:

Approximate number system Density perception Numerical cognition Numerosity perception Simultanagnosia Subitizing

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Area of Science:

Cognitive Neuroscience
Neuropsychology

Background:

Human numerosity judgments span a wide range, suggesting multiple underlying mechanisms.
Previous research indicates distinct attentional effects on low, intermediate, and high numerosity processing.

Observation:

A patient with simultanagnosia (PA) exhibited severe deficits in multiple object tracking.
PA showed significant impairments in discriminating low (3 dots) and high (64, 128 dots) numerosities, and dot-distances.

Findings:

PA's discrimination thresholds were unexpectedly preserved for intermediate numerosities (12, 16 dots).
PA's numerosity deficits followed a U-shaped function, correlating with attentional and spatial judgment impairments.

Implications:

These findings provide neuropsychological support for a three-system model of numerosity perception.
The study highlights the critical role of attention and spatial processing in different numerosity ranges.