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Updated: Jun 13, 2026
10:27
Training Synesthetic Letter-color Associations by Reading in Color
Published on: February 20, 2014
Neural basis of individual differences in synesthetic experiences
1Department of Psychology, University of Amsterdam, 1018WB Amsterdam, The Netherlands. R.Rouw@uva.nl
Summary
Synesthesia links private mental experiences to brain function. Grapheme-color synesthetes show distinct neural patterns for "in-mind" versus "outside-world" color perceptions, revealing unique brain mechanisms for subjective experiences.
Area of Science:
- Neuroscience
- Cognitive Science
- Psychology
Background:
- The relationship between subjective mental experiences and brain structure/function is poorly understood.
- Synesthesia, a condition where sensory experiences trigger additional perceptions, offers a unique model for studying stable phenomenological traits.
- Grapheme-color synesthesia, where letters/numbers evoke colors, is a common form studied here.
Purpose of the Study:
- To investigate the neural basis of different qualitative properties of synesthetic experiences.
- To explore individual differences in grapheme-color synesthesia, specifically the distinction between 'associator' (in-mind) and 'projector' (outside-world) experiences.
- To correlate subjective synesthetic experiences with specific brain structure and function.
Main Methods:
- Utilized voxel-based morphometry and functional magnetic resonance imaging (fMRI) to examine gray matter structure and function.
- Studied a cohort of 42 grapheme-color synesthetes (16 projectors, 26 associators) and non-synesthetes.
- Analyzed individual differences in synesthetic experiences.
Main Results:
- Identified shared neural mechanisms for all grapheme-color synesthetes, particularly in the posterior superior parietal lobe involved in sensory integration.
- Found distinct neural mechanisms underlying 'in-the-mind' (associator) versus 'outside-world' (projector) synesthetic experiences.
- Associated 'outside-world' experiences with visual, auditory, motor, and frontal brain areas; 'in-the-mind' experiences with the hippocampus and parahippocampal gyrus (memory-related areas).
Conclusions:
- Subjective differences in synesthesia are underpinned by distinct neural mechanisms.
- The functional properties of mediating brain mechanisms align with the characteristics of subjective experiences.
- This study elucidates the neural correlates of different types of synesthetic perception.
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