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Anna Grubert, Martin Eimer; Temporal dynamics of attentional templates. Journal of Vision 2017;17(10):74. doi: 10.1167/17.10.74.
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© ARVO (1962-2015); The Authors (2016-present)
Attentional templates (representations of target features) are activated prior to search to guide spatial attention to target-matching events in the visual field. To investigate the temporal dynamics of preparatory template activation, we developed a new rapid serial probe presentation technique and measured N2pc components to these probes during single-colour and multiple-colour search. Participants searched for colour-defined targets that appeared together with different-colour distractors in circular search displays. During this task, a continuous stream of circular probe displays appeared at a different location closer to fixation. These task-irrelevant displays contained one coloured and five grey items. All probe and search displays were presented for 50ms and were separated by a 200ms stimulus onset asynchrony. In Experiment 1, target colour was constant (e.g., red), and probe arrays contained either a target-colour or a distractor-colour singleton. Only target-matching probes triggered an N2pc, indicative of template-guided attentional capture. No N2pc was elicited for probes that appeared directly after a preceding search display and the N2pc was largest for probes that immediately preceded the next search display. This demonstrates that template activation is not constant, but is modulated in line with temporal task parameters. A control experiment showed that the apparent transient template de-activation following search displays is not an automatic consequence of target identity or response-related processing. Analogous N2pc results were found in Experiment 2, where target colour alternated predictably across successive search displays (e.g., red, green, red), and singleton probes either matched the previous or the upcoming target colour. Both types of probes triggered a similar N2pc pattern, suggesting simultaneous activation of colour target templates during multiple-colour search even when the upcoming target colour is known. These results show that our new rapid serial probe presentation method can provide novel electrophysiological insight into the time course of attentional templates.
Meeting abstract presented at VSS 2017
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