Unconscious Attentional Capture Effect Can be Induced by Perceptual Learning

Previous ERP studies have shown that N2pc serves as an index for salient stimuli that capture attention, even if they are task irrelevant. This study aims to investigate whether nonsalient stimuli can capture attention automatically and unconsciously after perceptual learning. Adult subjects were trained with a visual search task for eight to ten sessions. The training task was to detect whether the target (triangle with one particular direction) was present or not. After training, an ERP session was performed, in which subjects were required to detect the presence of either the trained triangle (i.e., the target triangle in the training sessions) or an untrained triangle. Results showed that, while the untrained triangle did not elicit an N2pc effect, the trained triangle elicited a significant N2pc effect regardless of whether it was perceived correctly or not, even when it was task irrelevant. Moreover, the N2pc effect for the trained triangle was completely retained 3 months later. These results suggest that, after perceptual learning, previously unsalient stimuli become more salient and can capture attention automatically and unconsciously. Once the facilitating process of the unsalient stimulus has been built up in the brain, it can last for a long time.