Abstract
The attentional blink (AB) is typically thought to represent attenuated post-perceptual processing of the second of two targets identified in an RSVP stream. However, recent fMRI evidence has demonstrated that BOLD responses in visual cortex, including V1, can be attenuated during the AB. While this evidence is consistent with the notion that earlier stages of processing are also attenuated during the AB, recent EEG evidence has shown that the striate cortex generated C1 ERP component is not attenuated during the AB (Jacoby et al. 2011). This EEG evidence suggests that the attenuated BOLD responses in V1 observed in the fMRI studies resulted from feedback from higher-order processing areas. These studies provide suggestive neural evidence that the AB may arise from perceptual failures as well as post-perceptual failures, but the precise impact of the AB on the earliest stages of neural processing remains unclear. To investigate this issue, we manipulated first target (T1) difficulty and used EEG to measure neural activity in response to a task-irrelevant probe present in upper or lower visual fields simultaneously with the centrally presented second target (T2). Analysis of the ERP data (n=11) confirmed that the C1 component evoked by the probe presentation at T2 was not suppressed during the AB when compared to outside the AB (p>.05) and it was not modulated by T1 difficulty (p>.05). However, mean ERP amplitude in the 220-240ms time range measured at occipital and parietal electrodes contralateral to the probe location was significantly reduced under increased T1 difficulty inside the AB, but not outside the AB (p<.05). These findings provide further evidence that V1 activity is not reduced during the AB, not is it modulated by increased attentional demands imposed by T1. However, the findings do suggest that T1 difficulty modulates activity evoked by task-irrelevant information presented during the AB.
Meeting abstract presented at VSS 2013