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Anomalous global effects induced by 'blind' distractors in visual hemifield defects
S Van der Stigchel1, T C W Nijboer, D P Bergsma
1Department of Experimental Psychology, Helmholtz Institute, Utrecht University, The Netherlands. S.VanderStigchel@uu.nl
Brain and Cognition
|July 20, 2010
Summary
Stimuli in a blind visual field can influence eye movements, even without awareness. This study found blind field distractors paradoxically shifted saccade endpoints away from them, unlike in normal vision.
Area of Science:
- Neuroscience
- Ophthalmology
- Visual perception
Background:
- Stimuli in the blind visual field can trigger oculomotor competition without conscious awareness.
- The global effect, a saccade endpoint shift, typically occurs when targets and distractors are near each other.
Purpose of the Study:
- To investigate if blind hemifield distractors can induce a global effect in individuals with optic radiation or striate cortex lesions.
- To compare the oculomotor response to blind hemifield distractors with responses to visible hemifield distractors.
Main Methods:
- Studied three participants with lesions affecting visual processing pathways (optic radiations or striate cortex).
- Presented stimuli in the blind hemifield and measured saccade endpoint shifts.
Main Results:
- Blind field distractors significantly shifted saccadic endpoints in two of three participants.
- The shift direction was paradoxical: endpoints moved away from blind field distractors.
- In contrast, visible hemifield distractors elicited the normal global effect (shift towards the distractor).
Conclusions:
- Elements in the blind visual field can modulate oculomotor system interactions.
- These interactions may differ significantly from those observed in normal vision.
- Further research is needed to understand the mechanisms behind these paradoxical oculomotor responses.
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