Perception of Dynamic Point Light Facial Expression

This study uses point light displays both to investigate the roles of global and local motion analyses in the perception of dynamic facial expressions and to measure the information threshold for reliable recognition of emotions. We videotaped the faces of actors wearing black makeup with white dots while they dynamically produced each of 6 basic Darwin/Ekman emotional expressions. The number of point lights was varied to systematically manipulate amount of information available. For all but one of the expressions, discriminability (d′) increased approximately linearly with number of point lights, with most remaining largely discriminable with as few as only 6 point lights. This finding supports reliance on global motion patterns produced by facial muscles. However, discriminability for the happy expression was notably higher and largely unaffected by number of point lights and thus appears to rely on characteristic local motion, probably the unique upward curvature of the mouth. The findings indicate that recognition of facial expression is not a unitary process and that different expressions may be conveyed by different perceptual information, but in general, basic facial emotional expressions typically remain largely discriminable with as few as 6 dynamic point lights.

Auditory capture of visual apparent motion, both laterally and looming

Traditional tests of multisensory stimuli typically support that vision dominates spatial judgments and audition dominates temporal ones. Here, we examine if unambiguous auditory spatial cues can capture ambiguous visual ones in judgments of direction of apparent motion. The visual motion judgments include both lateral movement and movement in depth, each when coupled with auditory stimuli moving at one of four rates. Experiment 1 tested lateral visual movement judgments (leftward vs rightward) coupled with auditory stimuli that moved laterally. Experiment 2 tested depth visual movement judgments (approaching vs receding) coupled with auditory stimuli that got louder or quieter. Results of Experiment 1 revealed and replicated an overall leftward motion bias, but with additional acoustic capture to experience visual movement away from the side on which sound initially occurred, and no effect of auditory motion speed. Results of Experiment 2 revealed and replicated an approaching motion bias, but with no effect of initial sound intensity, and an additional systematic capture effect of auditory motion speed. Faster changes in acoustic intensity produced larger visual motion capture consistent with the direction of acoustic intensity change. Findings of both experiments generalized over conditions of listening device (head phones vs speakers) and test-setting (Laboratory vs Web-based data-collection). The leftward and approaching motion bias results replicate previous research. Our principal new findings, the auditory motion capture effects, confirm the multisensory nature of dynamic spatial perception and support that extent of inter-sensory capture is a function of the relative reliability of spatial information acquired by each sensory modality.

Baseball's sight-audition farness effect (SAFE) when umpiring baserunners: Judging precedence of competing visual versus auditory events

Baseball umpires judge force-outs at first-base by comparing the sound of ball-mitt contact to the sight of foot-base contact. This study examines if distant observer judgments of the temporal order of visual versus auditory events are biased due to the slow speed of sound, or if judgments made from farther away systematically compensate for acoustic delays of sound. Seventy and 81 participants observed videos projected onto a gymnasium wall from 0, 100, or 200 feet, and made multisensory precedence judgments regarding which cue occurred first, visual ("safe") or auditory ("out"). Experiment 1 used visual flash versus auditory click; Experiment 2, colliding visual stimuli versus auditory click; Experiment 3, films of base-runners with basemen catching balls. Our findings confirm a sight-audition farness effect (SAFE) bias such that when visual information is impoverished, distant observers making multisensory precedence judgments typically do not fully compensate for acoustic delays due to the slow speed of sound, which can lead to disagreements. In short, distant fans will tend to have more of a bias to experience baserunners as safe, compared with nearby umpires. (PsycINFO Database Record (c) 2018 APA, all rights reserved).