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Arielle Veenemans, Patrick Cavanagh; Tailgate masking: the obliterating effect of the unattended pre-mask. Journal of Vision 2011;11(11):216. doi: https://doi.org/10.1167/11.11.216.
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In standard masking paradigms it is not possible to attend to a target without also attending to the masks that precede and/or follow it. However, in this experiment, we used an apparent motion paradigm where observers could attentively track a central target location without attending to the masks, allowing us to examine if the strength of masking depends on the amount of attention falling on the masks.
Three adjacent stimuli – a mask, a target, and a mask – stepped along a path circling fixation. The displacement on each step matched the spacing between the stimuli so that each location received a temporal sequence of mask-target-mask. At high target contrasts, the target was clearly visible at the location between the masks. At lower contrasts however, the target vanished, leaving a blank space between the two masks. This result was robust over a wide range of timings and spacings.
We then changed the spacing of either the preceding or the following mask so that one of the masks no longer fell on the target location on each step. When only the mask preceding the target was aligned with the target, the masking was slightly reduced compared to when both pre- and post-masks were aligned on the target. The post-mask alone had little effect on the target visibility. This indicates that masking can occur even when no attention is allocated to the mask but the effectiveness of unattended masks arises principally from the pre-mask (forward masking).
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