Effects of galvanic vestibular stimulation on response interference following visual motion primes.

One impressive demonstration of a counter-regulation of unfounded motor responses comes from response priming with moving dot stimuli: Participants respond faster to the direction of static arrow targets if they are preceded by dots moving in the opposite compared to the same direction (i.e., negative compatibility effect, NCE). This NCE occurs with stimulus onset asynchronies (SOAs) above 200 ms; with SOAs below 200 ms, a positive compatibility effect (PCE) occurs. The current research aimed to investigate the involvement of the vestibular system in the NCE. Galvanic vestibular stimulation (GVS) with either right-anodal/left-cathodal (R-GVS) or left-anodal/right-cathodal (L-GVS) stimulation or no stimulation was applied. We expected no influence of GVS on the PCE, and differential influences on the NCE of R-GVS vs. L-GVS. The results largely confirmed these expectations. In a short SOA condition (147 ms), PCEs occurred independent of GVS. In contrast, the NCE in the longer SOA condition (360 ms) was influenced by vestibular stimulation: There was a significant NCE with R-GVS, but non-significant effects with L-GVS as well as with no vestibular stimulation. This strikingly demonstrated the important influence of the vestibular system for response regulation processes as reflected in response priming.