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Pi-Chun Huang, Robert Hess; Dynamics of collinear facilitation: Fast yet sustained. Journal of Vision 2008;8(6):272. doi: 10.1167/8.6.272.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose. It is well established that the detection of a luminance-defined Gabor is improved if measured in the presence of two high contrast aligned flanking Gabors and this is termed collinear facilitation. Here the temporal properties in collinear facilitation were investigated in order to better the understanding of its underlying mechanism. Methods and Results. Collinear facilitation was measured at different onset times of the target (2 cpd, 1 octave bandwidth, 80ms presenting time) when the contrast of the flanks was modulated at 1 Hz (1 sec) and the results showed that facilitation occurred in the spatially out-of-phase condition, suggesting a long-lasting, sustained facilitatory effect. In experiment 2, the order between target and flanks in collinear facilitation was investigated by varying the ISI between target and flanks, both of which were presented for 50ms. Results were collected for 3 different target-flank distances (2, 3, 6 λ). The results showed that the amount of facilitation decreased with the time lag between target and flanks and the peak was shifted with the target-flanks distance. However, we also found the peak facilitatory effect occurred when the target preceded the flanks. The results showed that maximal facilitation occurs at or before (not after) flank presentation, suggesting fast dynamics. Conclusion. The dynamics of collinear facilitation are complex. Facilitation occurs rapidly (tens of milliseconds) lowering thresholds at and sometimes before flank presentation but its effects are sustained (hundreds of milliseconds).
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