Multisensory integration can alter information processing, and previous research has shown that such processes are modulated by sensory switch costs and prior experience. Here we report an incidental finding demonstrating, for the first time, the interplay between these processes and experimental factors, specifically the presence of the experimenter in the testing room. Experiment 1 demonstrates that multisensory motor facilitation in response to audiovisual stimuli is higher in those trials in which the sensory modality switches than when it repeats. Those participants (...) who completed the study while alone exhibited increased RT variability. Experiment 2 replicated these findings using the letters “b” and “d” presented as unisensory stimuli or congruent and incongruent multisensory stimuli. Multisensory enhancements were inflated following a sensory switch; that is, congruent and incongruent multisensory stimuli resulted in significant gains following a sensory switch in the monitored condition. However, when the participants were left alone, multisensory enhancements were only observed for repeating incongruent multisensory stimuli. These incidental findings therefore suggest that the effects of letter congruence and sensory switching on multisensory integration are partly modulated by the presence of an experimenter. (shrink)

Linking arbitrary shapes to personal labels or reward values results in immediate processing benefits for those stimuli that happen to be associated with the self or high rewards in perceptual matching tasks. Here we further explored how social and reward associations interact with multisensory stimuli by pairing labels and objects with tones. We also investigated whether self and reward biases persist for multisensory stimuli with the label removed after an association had been made. Both high reward stimuli and those associated (...) with the self, resulted in faster responses and improved discriminability, which persisted for multisensory stimuli even when the labels were removed. However, these self- and reward-biases partly depended on the specific alignment between the physical tones and the conceptual order. Performance for reward associations improved when the endpoints of low or high rewards were paired with low or high tones; meanwhile, for personal associations, there was a benefit when the self was paired with either low or high tones, but there was no effect when the stranger was associated with either endpoint. These results indicate that, unlike reward, social personal associations are not represented along a continuum with two marked endpoints but rather with a single reference point. (shrink)