Abstract
Cueing attention after the disappearance of visual stimuli biases which items will be remembered best (Sperling, 1960; Sligte et al., 2008). The classical interpretation is that post-cueing influences memory consolidation, but not subjective visual experience. We recently challenged this view by showing that post-cued attention can improve objective and subjective report of a single item at threshold-contrast (Sergent et al., 2013). This suggests that conscious perception itself could be influenced retroactively. Here we tested whether post-cued attention can increase one's chances of seeing a stimulus, or whether it merely allows a more precise recall of its features. Attention was cued to the right or left side of a visual display after a single, threshold-contrast Gabor patch had been presented on the same or opposite side. Subjects then reported the precise orientation of the target by matching the orientation of a probe Gabor. A mixture-model analysis of this continuous measure of angular error allowed estimating both the percentage of guesses and the precision of encoding for non-guesses (Zhang & Luck, 2008). Post-cueing at the correct location had no influence on the precision of the reported angle, but significantly decreased the number of guesses. This suggests that post-cued attention in this instance induces discrete shifts in conscious access to the target percept, rather than preventing a decline in the resolution of remembered features. Using a similar approach in an iconic memory setting with several high-contrast items, we further showed that the performance advantage conferred by post-cueing is attributable not only to the maintained precision of perceptual information (as classically assumed), but also to an increased probability of accessing this information. These results suggest that attention can retrospectively trigger conscious access to sensory traces that were not consciously accessed in the first place.
Meeting abstract presented at VSS 2015