A shared numerical magnitude representation evidenced by the distance effect in frequency-tagging EEG

Area of Science:

• Cognitive Neuroscience
• Neuroscience
• Psychology

Background:

• Humans can abstract numerical information from diverse codes and contexts.
• Debate exists on whether magnitude information access uses common or distinct brain representations.

Purpose of the Study:

• To investigate if numerical magnitude processing relies on shared neural representations across different number codes.
• To identify a reliable neural marker for magnitude representation shared across various numerical formats.

Main Methods:

• Electrophysiological responses were recorded in humans.
• Stimuli included rapid streams of numbers (6 Hz) in varying codes: Arabic digits, number words, dot patterns, and finger configurations.
• Deviant numerosity variations (every five items) were presented to elicit discrimination responses.

Main Results:

• Clear discrimination responses (1.2 Hz) over parieto-occipital electrodes indicated abstraction and generalization of numerical information across codes.
• Larger right-hemispheric responses for distant numerical deviations (e.g., base "2", deviant "8") compared to close deviations (e.g., base "2", deviant "3") suggest magnitude processing.
• Neural responses correlated with behavioral performance on an independent numerical comparison task, supporting the distance effect.

Conclusions:

• A shared neural representation for numerical magnitude exists across different codes (digits, words, patterns, fingers).
• The study provides an unambiguous neural marker for this shared magnitude representation.
• Findings support a generalized system for numerical magnitude processing in the human brain.