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Keith A. Schneider, Daphne Bavelier; Components of visual prior entry. Journal of Vision 2002;2(7):439. doi: https://doi.org/10.1167/2.7.439.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The prior entry hypothesis suggests that attention accelerates visual processing, reducing the latency to perception for attended stimuli. Historical evidence for the hypothesis has been mixed, and the purpose of this study is to compare the contributions of attention, response bias, and sensory facilitation to the observed apparent prior entry effects. Methods: In separate sessions, observers judged the apparent simultaneity (SJ) or temporal order (TOJ) of the onsets of two peripheral targets, to one of which attention was oriented with either exogenous, endogenous, gaze-directed, isoluminant exogenous or multiple exogenous cues. The cue lead times (CLT) and the presentation intervals (SOA) between the targets were systematically varied. Results: The points of subjective simultaneity (PSS), the SOA at which the observers were maximally uncertain about the order of the targets, shifted significantly for the TOJ as a function of CLT for all cue types in a manner expected from the temporal dynamics of attention, however, decision models that included response biases could completely account for these shifts. The SOAs at which the SJ was maximum were not significantly different from zero for the endogenous and gaze-directed cues and were smaller than the TOJ shifts in the PSS for the exogenous cues. For multiple exogenous cues, the shift in the SJ maximum decreased with the number of cues, from about 20 ms with one cue to an asymptote of about 10 ms for six or more cues. Conclusions: Prior entry may only occur for attentional cues that cause transient activity at the target location, and the effects of these cues are composed of roughly equal attentional and non-attentional components. The results from TOJ experiments are difficult to interpret due to the contribution of response biases, but the SJ can function as a reliable test of prior entry. Prior entry is not a general property of attention but rather more likely a bottom-up sensory phenomenon.
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