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Maria Lev, Uri Polat; A time window for temporal facilitation. Journal of Vision 2011;11(11):1070. doi: 10.1167/11.11.1070.
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© ARVO (1962-2015); The Authors (2016-present)
Collinear facilitation is an enhancement in the visibility of a target by laterally placed collinear flankers (COL). A non-collinear configuration (parallel, side-by-side, SBS) produces less facilitation. In our previous study (Lev & Polat; When simultaneous presentation results in backward masking VSS 2010), we explored the facilitation using ERP recording and found that the latency of SBS is delayed by about 10 ms compared to COL. The results suggest that the temporal delay is underlying the reduced facilitation. Here we report results from a study (behaviour and ERP) in which we presented the flankers (in either COL or SBS configuration) at target-flankers separation of 3λ (duration = 60 ms) either before the target (forward masking) (ISI = 20, 40, or 60 ms, SOA = 80, 100, or 120 ms) or simultaneously with the target (ISI = 0). We found that presenting the flankers 20 ms before the target enhanced the response speed, resulting in a shorter latency of the P1 component about 10 ms for both COL and SBS, compared to the simultaneous presentation (ISI = 0). This effect was not found for ISI of 40 and 60 ms. Behaviour data support the ERP results. The timing that we used doesn't suggest an attentional confound. Altogether, the results support the suggestion that the signal evoked by the flankers in both COL and SBS configurations is delayed due to slow lateral prorogation time. Thus, forward presentation of 20 ms enables a better temporal matching of lateral and target signals (temporal integration), boosting up lateral facilitation.
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