Suppression during binocular rivalry broadens orientation tuning.
During binocular-rivalry suppression, an ordinarily visible stimulus is erased from awareness, but how is the sensory representation of that stimulus affected? Although it is established that rivalry suppression attenuates signal strength, the influence of suppression on signal fidelity remains unknown. Here, we show that noise plays a hitherto undiscovered role in the degradation of the percept under suppression. In Experiment 1, we measured psychometric functions for a stimulus presented under dominance and suppression, and found that the slope of these functions was shallower under suppression-a result suggesting that the signal representation was rendered noisier. Experiment 2 then revealed the source of this noise: An examination of the influence of suppression on the orientation bandwidth of noise masking showed that tuning bandwidth is significantly broadened under suppression. Thus, the discriminability of a suppressed stimulus is weakened not only by a general decrease in signal strength, but also by broader orientation tuning that introduces more noise in the neural representation of the suppressed stimulus.
Department of Psychology, Vanderbilt University, Nashville, TN 37203, USA. s.ling@vanderbilt.edu
Sam
S
Ling
Randolph
R
Blake
D001288:Attention; D001364:Awareness; D015350:Contrast Sensitivity; D004192:Discrimination, Psychological; D006801:Humans; D007600:Judgment; D009949:Orientation; D010364:Pattern Recognition, Visual; D010470:Perceptual Masking; D011601:Psychophysics; D011930:Reaction Time; D012684:Sensory Thresholds; D015357:Vision Disparity