The role of attention and response requirements on ERP correlates of auditory awareness

Abstract

Previous research on electrophysiological correlates of auditory awareness has found both an early “auditory awareness negativity” (AAN) and late, “late positivity” (LP) as potential markers of auditory awareness. Earlier studies have sought to separate correlates of auditory awareness from response requirements but have come up with mixed results. Furthermore, no previous studies have investigated the effects of attention on the recently discovered correlates of auditory awareness. We implemented a GO / NOGO paradigm to control for both attention and response requirements, whilst measuring the effects of the latter on previously discovered correlates of auditory awareness AAN and LP using a factorial mass univariate approach. The results show a prolonged AAN for aware trials starting around 250 ms post stimulus, a relatively late LP in 450 - 600 ms post stimulus when the interaction of response requirements was factored in with awareness, a mid-latency LP for awareness and response requirement interaction around 500 ms and a late LP starting from 700 ms post stimulus related to response requirements and attention but not awareness. Given the two-part structure of the LP component, the result seems to corroborate earlier studies suggesting the earlier part of LP is domain specific, while the later part is domain-general. The scalp topography of AAN was left lateralised possibly because the stimuli were syllables. We also found a negativity after around 400 ms after stimulus onset, which could be the language-related N400 component. The results are in line with theories that regard the AAN as the earliest correlate of auditory awareness and LP as later correlate of access consciousness. The early AAN was not affected by attention, while the later LP showed modulation by both attention and response requirements.