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Sage EP Boettcher, Freek van Ede, Anna C Nobre; Neural indices of proactive target templates. Journal of Vision 2019;19(10):247c. doi: https://doi.org/10.1167/19.10.247c.
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In perception, representational templates are proposed to be used proactively to anticipate target stimuli and facilitate performance. We designed a novel task and recorded EEG to test for the neural instantiation of representations of anticipated targets. In an associative-cueing task, observers were presented with a cue followed by a target on each trial. One of three possible targets was presented for 30ms followed by a mask and a forced choice discrimination response. Half of the cues were predictive of the target identity for two of the targets (67% validity) while the remaining cues were neutral (33% chance for each of the three potential targets to follow). The remaining target had an occurrence probability of 33%, irrespective of the preceding cue. Importantly, two distinct identity cues predicted the same target, enabling us to tease apart activity associated with cue vs. target representations. Analysis of the event related potentials locked to the onset of the cue indicates an effect of identity cues relative to the neutral cues – despite the fact that all cues predicted the occurrence of a target after the same interval in the same location. Specifically, we see an early posterior positivity followed by a late frontal negativity for identity relative to neutral cues. Additionally, we used multivariate pattern analysis to investigate whether the identity of the predicted target could be decoded during the cue period, independently from cue-related differences. This revealed traces of the upcoming target identity in similar periods as the observed ERP differences. The instantiation of a target template from memory thus appears to unfold dynamically in time, and to be reflected in complementary signatures of the EEG. In sum, we provide evidence for a dynamic predictive perceptual mechanism which can be used to facilitate the processing of incoming visual information.
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