Inability to move one's face dampens facial expression perception.

Humans rely heavily on facial expressions for social communication to convey their thoughts and emotions and to understand them in others. One prominent but controversial view is that humans learn to recognize the significance of facial expressions by mimicking the expressions of others. This view predicts that an inability to make facial expressions (e.g., facial paralysis) would result in reduced perceptual sensitivity to others' facial expressions. To test this hypothesis, we developed a diverse battery of sensitive emotion recognition tasks to characterize expression perception in individuals with Moebius Syndrome (MBS), a congenital neurological disorder that causes facial palsy. Using computer-based detection tasks we systematically assessed expression perception thresholds for static and dynamic face and body expressions. We found that while MBS individuals were able to perform challenging perceptual control tasks and body expression tasks, they were less efficient at extracting emotion from facial expressions, compared to matched controls. Exploratory analyses of fMRI data from a small group of MBS participants suggested potentially reduced engagement of the amygdala in MBS participants during expression processing relative to matched controls. Collectively, these results suggest a role for facial mimicry and consequent facial feedback and motor experience in the perception of others' facial expressions.

Individuals with schizophrenia display behaviour inconsistent with learned social impressions during a gambling task.

Many studies of social perception and judgement have required individuals to make evaluations of social parameters based on static presentations of social stimuli. In the current study, we assessed whether individuals with a schizophrenia spectrum disorder and community controls differed in their judgements of others based on a series of computerized encounters designed to simulate impression formation over time. Twenty-eight community controls and 29 individuals with a schizophrenia spectrum disorder completed 25 gambling interactions with three different computer partners. After interacting with each partner, subjects rated how much they liked, trusted, and would like to play again with each partner. Results indicated that while individuals with schizophrenia rated the three partners differently (evaluating partners who returned more money higher than partners who returned less money), they did not adjust their gambling strategies with the different partners. Community controls adjusted the amount of money they gambled with the different partners, gambling more with partners that returned more money and gambling less with partners who returned less money, despite not rating the neutral and positive partners significantly differently from one another. These results suggest differences in behavioural strategies and social evaluation practices between community controls and individuals with schizophrenia. PRACTITIONER POINTS: Schizophrenia (SZ) and community control (CC) participants evaluate virtual partners on a gambling task in accordance with their behaviour (e.g., positive > neutral > negative in terms of trustworthiness, how much they liked them, and the likelihood that they would play with that individual again). Individuals with schizophrenia gambled equally with neutral, negative, and positive partner. Individuals with schizophrenia demonstrate an intact ability to form social impressions based on others' behaviour. However, subsequent behaviour does not parallel the formed impression (i.e., changing their gambling amount so that they are betting less money with a virtual partner they know is untrustworthy).

Endogenous visuospatial attention increases visual awareness independent of visual discrimination sensitivity.

Visuospatial attention often improves task performance by increasing signal gain at attended locations and decreasing noise at unattended locations. Attention is also believed to be the mechanism that allows information to enter awareness. In this experiment, we assessed whether orienting endogenous visuospatial attention with cues differentially affects visual discrimination sensitivity (an objective task performance) and visual awareness (the subjective feeling of perceiving) during the same discrimination task. Gabor patch targets were presented laterally, either at low contrast (contrast stimuli) or at high contrast embedded in noise (noise stimuli). Participants reported their orientation either in a 3-alternative choice task (clockwise, counterclockwise, unknown) that allowed for both objective and subjective reports, or in a 2-alternative choice task (clockwise, counterclockwise) that provided a control for objective reports. Signal detection theory models were fit to the experimental data: estimated perceptual sensitivity reflected objective performance; decision criteria, or subjective biases, were a proxy for visual awareness. Attention increased sensitivity (i.e., improved objective performance) for the contrast, but not for the noise stimuli. Indeed, with the latter, attention did not further enhance the already high target signal or reduce the already low uncertainty on its position. Interestingly, for both contrast and noise stimuli, attention resulted in more liberal criteria, i.e., awareness increased. The noise condition is thus an experimental configuration where people think they see the targets they attend to better, even if they do not. This could be explained by an internal representation of their attentional state, which influences awareness independent of objective visual signals.

Elevated arousal levels enhance contrast perception.

Our state of arousal fluctuates from moment to moment-fluctuations that can have profound impacts on behavior. Arousal has been proposed to play a powerful, widespread role in the brain, influencing processes as far ranging as perception, memory, learning, and decision making. Although arousal clearly plays a critical role in modulating behavior, the mechanisms underlying this modulation remain poorly understood. To address this knowledge gap, we examined the modulatory role of arousal on one of the cornerstones of visual perception: contrast perception. Using a reward-driven paradigm to manipulate arousal state, we discovered that elevated arousal state substantially enhances visual sensitivity, incurring a multiplicative modulation of contrast response. Contrast defines vision, determining whether objects appear visible or invisible to us, and these results indicate that one of the consequences of decreased arousal state is an impaired ability to visually process our environment.