Unconscious Perceptual Learning: Periphery versus Fixation
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Perceptual Learning can be defined as training-induced improvement in the performance of perceptual tasks. While the effects of attention on conscious perceptual learning are well established, attentional influences in the absence of stimulus awareness are less explored. Carmel & Carrasco (2012b) examined whether differential deployment of spatial attention can affect perceptual learning for unconsciously perceived targets and used Continuous Flash Suppression to suppress stimuli from visual awareness. During target presentation, participants performed a simple task which directed spatial attention towards peripheral locations along two diagonals: While the first diagonal engaged attention on 80% of trials, the second diagonal was only attended on 20% of trials. Despite this unbalanced distribution of attention, results revealed a generalisation of unconscious perceptual learning and demonstrated performance improvements across all peripheral locations. Following up on this work, the present study used an experimental design very similar to Carmel & Carrasco (2012b) and manipulated spatial attention in two different conditions: In the Periphery Condition, a single diagonal was attended on 100% of trials and thus directed attention to only two peripheral locations. In the Fixation Condition, attention was deployed to the display centre. Directing attention in the Periphery Condition resulted in generalised perceptual learning and hence induced learning transfer from attended to previously unattended locations. In the Fixation Condition, on the other hand, perceptual learning could not be found. Overall, these findings suggest that deployment of spatial attention to a subset of peripheral locations is sufficient to induce a generalisation of unconscious perceptual learning. Moreover, these results highlight that attending to the periphery is not only sufficient, but also necessary for unconscious perceptual learning to occur.