Figure 1. Motion generation and experimental setup.

Subjects were positioned at the centre of a 1 meter radial arc extending from −90° to 90° along the audio-visual horizon. Their heads remained in a fixed position, stabilized by a chin rest and motion direction was alternated between trials. HRIRs from adjacent positions spaced by θ° were convolved with the broadband input stimulus before being sequentially played to achieve apparent auditory motion, presented via headphones. The auditory stimuli were spatially offset from visual stimuli by an amount μ° throughout the motion path. Subjects made a 2AFC judgement of the leading modality as it crossed the approximate midline.