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Do graphemes attract spatial attention in grapheme-color synesthesia?
G Volberg1, A S Chockley2, M W Greenlee1
1Institute for Psychology, University of Regensburg, Germany.
Neuropsychologia
|March 7, 2017
Summary
Grapheme-color synesthetes show increased brain activity in response to specific graphemes. However, these graphemes do not automatically attract spatial attention, challenging previous hypotheses.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Sensory Perception
Background:
- Grapheme-color synesthesia involves experiencing colors with achromatic graphemes.
- The role of spatial attention in synesthetic perception remains unclear.
Purpose of the Study:
- To investigate if grapheme inducers automatically attract spatial attention in synesthetes.
- To explore the neural mechanisms underlying synesthetic color experience.
Main Methods:
- Electroencephalography (EEG) was used to record oscillatory responses.
- Participants judged Gabor patch orientation after viewing achromatic inducers or colored non-inducers.
- Stimuli were presented in either the left or right visual hemifield.
Main Results:
- Synesthetes exhibited an early theta power increase for right-sided inducers, originating from the left fusiform gyrus.
- No alpha power asymmetries, suggesting no shift in spatial attention, were found.
- Synesthetes demonstrated heightened responsiveness in grapheme processing areas to inducers.
Conclusions:
- Synesthetic grapheme processing areas are more responsive in synesthetes.
- Contrary to the hypothesis, inducers did not automatically attract spatial attention in synesthetes.
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