The effect of height and shoulder-to-hip ratio on interpersonal space in virtual environment.

Previous research has associated men's physical features such as height and Shoulder-to-Hip Ratio (SHR) with dominance. Proxemics literature has suggested that the interpersonal space (comfort distance) increases in threatening and uncomfortable situations and decreases in unthreatening and comfortable situations. In the current study, we aimed to investigate the effect of different heights and SHRs on comfortable interpersonal distance by systematic manipulation of virtual confederates bodily features. More specifically, participants determined their comfort distances from virtual male confederates with different heights and SHRs in a virtual environment. We hypothesized that a virtual confederate's height and SHR influences the perception of interpersonal dominance; and consequently interpersonal space increases for taller and broader confederates as a result of increased interpersonal dominance. Results showed that comfortable interpersonal distance was positively associated with height for male participants, but not for female participants. No effect was found for shoulder width, neither for male nor female participants. Results were discussed in terms of the importance of height as a signal of dominance and fighting ability.

Audiovisual integration increases the intentional step synchronization of side-by-side walkers.

When people walk side-by-side, they often synchronize their steps. To achieve this, individuals might cross-modally match audiovisual signals from the movements of the partner and kinesthetic, cutaneous, visual and auditory signals from their own movements. Because signals from different sensory systems are processed with noise and asynchronously, the challenge of the CNS is to derive the best estimate based on this conflicting information. This is currently thought to be done by a mechanism operating as a Maximum Likelihood Estimator (MLE). The present work investigated whether audiovisual signals from the partner are integrated according to MLE in order to synchronize steps during walking. Three experiments were conducted in which the sensory cues from a walking partner were virtually simulated. In Experiment 1 seven participants were instructed to synchronize with human-sized Point Light Walkers and/or footstep sounds. Results revealed highest synchronization performance with auditory and audiovisual cues. This was quantified by the time to achieve synchronization and by synchronization variability. However, this auditory dominance effect might have been due to artifacts of the setup. Therefore, in Experiment 2 human-sized virtual mannequins were implemented. Also, audiovisual stimuli were rendered in real-time and thus were synchronous and co-localized. All four participants synchronized best with audiovisual cues. For three of the four participants results point toward their optimal integration consistent with the MLE model. Experiment 3 yielded performance decrements for all three participants when the cues were incongruent. Overall, these findings suggest that individuals might optimally integrate audiovisual cues to synchronize steps during side-by-side walking.

Judging time-to-passage of looming sounds: Evidence for the use of distance-based information.

Perceptual judgments are an essential mechanism for our everyday interaction with other moving agents or events. For instance, estimation of the time remaining before an object contacts or passes us is essential to act upon or to avoid that object. Previous studies have demonstrated that participants use different cues to estimate the time to contact or the time to passage of approaching visual stimuli. Despite the considerable number of studies on the judgment of approaching auditory stimuli, not much is known about the cues that guide listeners' performance in an auditory Time-to-Passage (TTP) task. The present study evaluates how accurately participants judge approaching white-noise stimuli in a TTP task that included variable occlusion periods (portion of the presentation time where the stimulus is not audible). Results showed that participants were able to accurately estimate TTP and their performance, in general, was weakly affected by occlusion periods. Moreover, we looked into the psychoacoustic variables provided by the stimuli and analysed how binaural cues related with the performance obtained in the psychophysical task. The binaural temporal difference seems to be the psychoacoustic cue guiding participants' performance for lower amounts of occlusion, while the binaural loudness difference seems to be the cue guiding performance for higher amounts of occlusion. These results allowed us to explain the perceptual strategies used by participants in a TTP task (maintaining accuracy by shifting the informative cue for TTP estimation), and to demonstrate that the psychoacoustic cue guiding listeners' performance changes according to the occlusion period.