Explicit Auditory Discrimination Improves During the Visual Attentional Blink

Abstract

Gating of sensory information is an elementary function, necessary for survival. In a series of studies, we investigated how sensory modalities interact in this process. We previously probed implicit allocation of multisensory attention during the Attentional Blink (AB), a failure to report a second target closely following first target detection (Haroush et al., ECVP 2007). In that study, we examined AB effects on the event-related Mismatch Negativity (MMN), which is ‘automatically’ elicited upon appearance of a deviant within a sequence of sounds. We found that MMN amplitude surprisingly increased during the AB, presumably underlying enhanced implicit auditory change detection processes. Here, we examined whether and how this effect translates into behavior, testing explicit auditory discrimination during a visual AB. Subjects were asked to identify two visual targets (T1&T2) embedded within a rapid distractor stimulus stream, and simultaneously perform an auditory discrimination task in a two-alternative-forced-choice, 2down-1up staircase paradigm. The first sound appeared at the beginning of the trial, (before visual T1), and the second simultaneously with visual T2, at variable SOAs. Three auditory protocol blocks were used with/without fixed reference tones to distinguish sensory classification from working-memory (WM) dependent discrimination (Nahum et al., 2009). When auditory discrimination was WM dependent, auditory performance during visual attentional blink trials significantly improved compared to trials where both visual targets were correctly reported. In contrast, sensory classification alone did not benefit from the visual AB, presumably because of its independence of WM. We conclude that attention-controlled WM resources that could not be used by the visual system during the AB are freed to be employed by the auditory system. Notably, this attention allocation is evident despite the additional resources taxed by task-switching. These results have implications for current theories of multiple information processing bottlenecks.