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Jong-Ho Nam; Investigating Spatial Frequency Channels shared by 1st- and 2nd-order texture processing. Journal of Vision 2004;4(8):538. doi: 10.1167/4.8.538.
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It was investigated to determine whether spatial frequency channels follow by 1st- and 2nd-order texture processing are shared or separated. It was conjectured that if frequency channels are shared for 1st- and 2nd0-order texture processing, an adaptation to a stimulus pattern of 1st-order texture will elevate a threshold of 2nd-order texture segregation. Otherwise, adaptation top to 1st-order stimulus affect detecting 1st-order texture, not 2nd-order. It was used IID (Independently, Identically Distributed) texture to generate stimulus pattern. Five different frequencies, two segregation orientations for 1st- and 2nd-order texture were used respectively. First, segregation thresholds for 1st- and 2nd-order texture were measure for each subject respectively. Second, a pure sinewave grating was introduced to observe changes of segregation thresholds after adaptation. The adapting sinewave grating was presented for one minute before experimental block began, and for one quarter second before a testing stimulus was presented in each trial. There was a threshold elevation for adapted condition when spatial frequency and segregation orientation was same. Furthermore, the same result pattern was obtained for 2nd-order texture stimuli. However, there was no systematic threshold elevation when segregation orientation was orthogonal or spatial frequencies were fairly different. It was interpreted that segregation processing are separated for 1st- and 2nd-order texture in an earlier stage, spatial frequency channels followed by them was shared.
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