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Updated: Dec 23, 2025
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Training Synesthetic Letter-color Associations by Reading in Color
Published on: February 20, 2014
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Reduced perceptual narrowing in synesthesia.
Daphne Maurer1, Julian K Ghloum2, Laura C Gibson2
1Department of Psychology, Neuroscience & Behaviour, McMaster University, Hamilton, ON, Canada L8S 4K1; maurer@mcmaster.ca.
Summary
Synesthesia may result from incomplete brain pruning. Synesthetes show enhanced ability to distinguish non-native sounds, faces, and inverted faces, suggesting broader perceptual benefits.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Developmental Psychology
Background:
- Synesthesia is a neurological trait involving cross-sensory experiences.
- A leading hypothesis suggests synesthesia arises from insufficient synaptic pruning in early development.
- This pruning refines neural pathways based on experience.
Purpose of the Study:
- To test the incomplete pruning hypothesis of synesthesia.
- To investigate if synesthetes possess superior discrimination abilities for percepts typically pruned during development.
Main Methods:
- Compared discrimination abilities of synesthetes and control groups.
- Tested discrimination of non-native phonemes (Hindi retroflex vs. dental), chimpanzee faces, and inverted human faces.
- Utilized multiple samples and testing sites for robust data.
Main Results:
- Synesthetes significantly outperformed control groups in all non-native discrimination tasks.
- Performance mirrored that of 6-month-old infants before experience-dependent pruning occurs.
- Superiority was consistent across phoneme, facial, and inverted facial stimuli.
Conclusions:
- Findings support the incomplete pruning hypothesis of synesthesia.
- Residual cortical connectivity in synesthesia may enhance perceptual abilities beyond specific synesthetic experiences.
- This suggests a broader role for synaptic pruning in shaping perceptual development.
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