Neural Markers of Speech Processing During Inattentional Deafness

Cognitive scientists have long debated the capabilities of non-conscious perception, defined as the level of processing of external stimuli that people do not consciously experience. While much is known about non-conscious visual perception, the auditory modality has received less focus. Here, we examine the level of processing for audible and intelligible spoken words that participants did not notice during the performance of another difficult visual task. Using repeated occurrences of such inattentional deafness, alongside objective and subjective awareness probes, we measure the processing of supraliminal, but undetected words. In two pre-registered EEG experiments (N = 67), we show a unique, temporally late, neural response that differentiates words from pseudowords in the absence of conscious awareness. Additionally, an exploratory analysis found a behavioral interference of undetected words with visual task performance. Both results were contingent on the relevance of word detection to participants, implying that auditory non-conscious processing is not automatic but goal-dependent. Overall, our results support flexible capabilities for non-conscious speech perception, suggesting the ability to integrate acoustic information over time.