Cite as:
Huang P, Chen I, Lee I, 2001, "Multiple spatial-frequency channels for the detection of orientation modulation patterns" Perception 30 ECVP Abstract Supplement

Multiple spatial-frequency channels for the detection of orientation modulation patterns

P Huang, I Chen, I Lee

Sensitivities of the second-order texture mechanisms to orientation modulation (OM) frequencies have been assessed by measuring subjects' detection thresholds for high micropattern-density OM gratings. The OM functions show a clear bandpass characteristic, peaking at 0.22 cycles deg^-1 with a bandwidth of 4.54 octaves. We investigated whether the OMF function is subserved by a single or multiple spatial-frequency channels with subthreshold summation experiments. OM contrast thresholds were measured for compound gratings containing two contrast-added sinusoidal OM components. The spatial-frequency ratios between the two components were 2, 3, 4.5, and 6. The two components were either in phase or out of phase. The results showed that the degrees of summation were inversely proportional to the spatial-frequency separations between components. For compound gratings composed of components with the spatial- frequency ratio of 3, the detection thresholds were insensitive to phase relationships between components. Our results thus support the multiple-spatial-frequency-channels model for the second-order OM detection.

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