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Yasuto Tanaka, Satoru Miyauchi, Masaka Misaki, Tomoe Hayakawa, Takara Tashiro; Asymmetrical long-range interaction between upper and lower visual hemifields. Journal of Vision 2005;5(8):724. doi: 10.1167/5.8.724.
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© ARVO (1962-2015); The Authors (2016-present)
According to previous studies of lateral connection using the Gabor lateral masking paradigm, the long-range interaction was found with collinear configuration where target-flanker direction was co-axial and co-oriented. No asymmetry was found between horizontal and vertical axes in fovea (Polat and Sagi 1993). Here we show asymmetrical long-range interaction between upper and lower visual fields. Horizontally oriented Gabor target was presented on the vertical meridian either at the upper or lower visual field (3.2 deg eccentricity). Eyes were fixated at the central spot. Two collinearly configured (=horizontal) Gabor stimuli were flanked simultaneously at the left and right sides of the target (lambda=sigma=0.2deg, duration=100ms, C=0.4) for each visual field. Contrast detection threshold for target was measured using the temporal 2AFC staircase method for different target-flanker distances ranging 3 to 24lambda. Normalized threshold (=comparison with no-flanker condition) facilitated up to 20 lambda with magnitude of 0.14+−0.04 log units (averaged over 3–20lambda, 4 observers) with the flanker-target presentation at the upper visual field. The facilitation was limited within the distance at 3 to 9lambda with the magnitude of 0.08+−0.02 log units with the presentation at the lower visual field. Similar asymmetry was found with other target eccentricities (1.6 degrees and 4.8 degrees). These results demonstrate that long-range interaction is extended and exaggerated to horizontal peripheral direction at the upper visual hemifield compared with the lower visual field, suggesting the asymmetrical horizontal long-range interaction between upper and lower visual fields occurring at early stages of visual processing.
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