The unnoticed zoo: Inattentional deafness to animal sounds in music

Inattentional unawareness potentially occurs in several different sensory domains but is mainly described in visual paradigms ("inattentional blindness"; e.g., Simons & Chabris, 1999, Perception, 28, 1059-1074). Dalton and Fraenkel (2012, Cognition, 124, 367-372) were introducing "inattentional deafness" by showing that participants missed by 70% a voice repeatedly saying "I'm a Gorilla" when focusing on a primary conversation. The present study expanded this finding from the acoustic domain in a multifaceted way: First, we extended the validity perspective by using 10 acoustic samples-specifically, excerpts of popular musical pieces from different music genres. Second, we used as the secondary acoustic signal animal sounds. Those sounds originate from a completely different acoustic domain and are therefore highly distinctive from the primary sound. Participants' task was to count different musical features. Results (N = 37 participants) showed that the frequency of missed animal sounds was higher in participants with higher attentional focus and motivation. Additionally, attentional focus, perceptual load, and feature similarity/saliency were analyzed and did not have an influence on detecting or missing animal sounds. We could demonstrate that for 31.2% of the music plays, people did not recognize highly salient animal voices (regarding the type of acoustic source as well as the frequency spectra) when executing the primary (counting) task. This uncovered, significant effect supports the idea that inattentional deafness is even available when the unattended acoustic stimuli are highly salient.