FIGURE 1.

Illustration of the setup and an audio-visual trial. Six speaker positions from –22.5 to 22.5° in steps of 9° are represented by black boxes. The curtain covering the speakers is only transparent for illustration purposes and was visually opaque and only acoustically transparent. A chin rest used to fixate the head is not displayed. At first, a green laser dot appeared as fixation point and participants could start the trial by pointing to the fixation dot and pressing a button. The trial started when the pointing error was below ± 10°. During a second interval, a step motor adjusted a second laser used for stimulus presentation. Auditory (indicated by blue waves) and visual (red light cone) stimuli were presented for 200 ms in synchrony. Participants could respond immediately by pointing toward the perceived direction and pressing a button on the pointer. Corrective feedback followed instantaneously in form of a centrally presented arrow. The color of the arrow (green for reward, red for no reward) and a unique sound indicated whether a reward was obtained. After a varying interval (600–800 ms) the green laser dot reappeared, and the participant could start the next trial. Avatar image adapted from “Low Poly Character” by TehJoran (2011) (https://www.blendswap.com/blend/3408) licensed under CC BY.