Shared capacity limitations in auditory scene analysis and central attention: Evidence from auditory search in a dual-task paradigm.

Auditory scene analysis enables listeners to segregate and group a mixture of sounds into coherent streams, but it remains controversial to what extent this process depends on the availability of central attention. While previous research suggests that the guidance of visual attention may be independent of central capacity limitations, it remains unclear whether auditory selective attention can operate in parallel with central attention. Across two online experiments, it was tested whether attentional search in complex auditory scenes is limited in capacity and subject to the central processing bottleneck using a dual-task paradigm with the locus-of-slack method. Participants were first asked to identify target sounds within auditory scenes of varying set sizes (1-8 sounds), either as a single task or together with a visual discrimination task at variable stimulus onset asynchronies (SOAs). Results from single-task blocks revealed robust auditory set-size effects on response times and error rates, indicating capacity limitations and serial processing during auditory scene analysis. In the dual-task paradigm, auditory search times increased at short SOAs, demonstrating a psychological refractory period. Critically, the auditory set-size effects persisted, but were not attenuated at short SOAs, suggesting that auditory search time has not been absorbed into the slack due to the central processing bottleneck. In contrast to some evidence from the visual attention literature, these findings indicate that auditory scene analysis and central attention depend on shared capacity limitations, thus highlighting the importance of attentional control in complex listening situations.