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Assessing Binocular Central Visual Field and Binocular Eye Movements in a Dichoptic Viewing Condition
Published on: July 21, 2020
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The object-based shift direction anisotropy is modulated by the horizontal visual field meridian.
Adam J Barnas1,2, Adam S Greenberg1,3
1Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
Quarterly Journal of Experimental Psychology (2006)
|January 27, 2024
Summary
The shift direction anisotropy (SDA), where horizontal attention shifts are faster than vertical, is reduced when the horizontal meridian is visually enhanced. This suggests meridians play a key role in how attention is reallocated.
Area of Science:
- Cognitive Neuroscience
- Visual Attention Research
- Human Perception
Background:
- Object-based attention reallocation across visual field meridians shows a faster horizontal than vertical shift (shift direction anisotropy, SDA).
- The meridians' role in the emergence of SDA requires further investigation, particularly concerning their modulatory influence.
Purpose of the Study:
- To investigate the modulatory role of visual meridians in the emergence of the shift direction anisotropy (SDA).
- To test the hypothesis that manipulating the horizontal meridian selectively modulates SDA, considering separate attentional resource pools in each cortical hemisphere.
Main Methods:
- Four experiments involved participants detecting targets on "L"-shaped objects with manipulated meridian local feature contrast.
- Manipulations included perceptually strong (visible lines, colour borders) and weak (illusory borders) enhancements of horizontal and vertical meridians.
- Reaction times (RTs) for horizontal and vertical shifts were recorded and compared across conditions.
Main Results:
- Weak meridian enhancements did not significantly alter SDA magnitude.
- Strong enhancements of the horizontal meridian significantly reduced SDA compared to vertical enhancement and no-enhancement conditions.
- The SDA was eliminated when the horizontal meridian was strongly enhanced with a visible line, making horizontal and vertical shift RTs equivalent.
Conclusions:
- The shift direction anisotropy (SDA) appears to emerge from the reallocation of object-based attention across the horizontal meridian.
- Findings support theories suggesting anatomical visual system segregations influence attentional resource allocation and inter/intra-hemispheric competition.
