Task-specific effects of looming audio: Influences on visual contrast and orientation sensitivity

Looming sounds are known to influence visual processing in various ways. Prior work suggests that performance on an orientation sensitivity task may be improved if visual presentation is preceded by looming audio, but not by non-looming audio. However, our recent work revealed that looming and non-looming alert sounds have a similar impact on performance in contrast sensitivity tasks. In the current study, we aim to reconcile these findings by comparing the effects of looming and non-looming sounds on contrast and orientation discrimination tasks within participants. Participants viewed tilted sinusoidal gratings and made judgments about their orientation (left/right). The gratings for the contrast discrimination task had low contrast and high deviation from vertical (±45°), whereas for the orientation discrimination task, they had a low deviation (less than ±2° from vertical) and full contrast. Immediately before visual stimulus presentation, there could be no sound, stationary sound, or looming sound. Sensitivity was measured as d' and compared across tasks and sound types. Our results indicate that neither task benefited more from looming sounds over stationary sounds, yielding no evidence for a looming bias in this domain. However, we found a differential effect between tasks, indicating that contrast discrimination was improved more by alert sounds than orientation discrimination, likely reflecting perceptual differences in the task types. Factors that may influence the effectiveness of looming sounds are discussed.