Adaptation to continuous perturbation of balance: progressive reduction of postural muscle activity with invariant or increasing oscillations of the center of mass depending on perturbation frequency and vision conditions

We investigated the adaptation of balancing behavior during a continuous, predictable perturbation of stance consisting of 3-min backward and forward horizontal sinusoidal oscillations of the support base. Two visual conditions (eyes-open, EO; eyes-closed, EC) and two oscillation frequencies (LF, 0.2 Hz; HF, 0.6 Hz) were used. Center of Mass (CoM) and Center of Pressure (CoP) oscillations and EMG of Soleus (Sol) and Tibialis Anterior (TA) were recorded. The time course of each variable was estimated through an exponential model. An adaptation index allowed comparison of the degree of adaptation of different variables. Muscle activity pattern was initially prominent under the more challenging conditions (HF, EC and EO; LF, EC) and diminished progressively to reach a steady state. At HF, the behavior of CoM and CoP was almost invariant. The time-constant of EMG adaptation was shorter for TA than for Sol. With EC, the adaptation index showed a larger decay in the TA than Sol activity at the end of the balancing trial, pointing to a different role of the two muscles in the adaptation process. At LF, CoM and CoP oscillations increased during the balancing trial to match the platform translations. This occurred regardless of the different EMG patterns under EO and EC. Contrary to CoM and CoP, the adaptation of the muscle activities had a similar time-course at both HF and LF, in spite of the two frequencies implying a different number of oscillation cycles. During adaptation, under critical balancing conditions (HF), postural muscle activity is tuned to that sufficient for keeping CoM within narrow limits. On the contrary, at LF, when vision permits, a similar decreasing pattern of muscle activity parallels a progressive increase in CoM oscillation amplitude, and the adaptive balancing behavior shifts from the initially reactive behavior to one of passive riding the platform. Adaptive balance control would rely on on-line computation of risk of falling and sensory inflow, while minimizing balance challenge and muscle effort. The results from this study contribute to the understanding of plasticity of the balance control mechanisms under posture-challenging conditions.     

You must have been a beautiful baby: ratings of infant facial attractiveness fail to predict ratings of adult attractiveness

Facial attractiveness has been studied extensively, but little research has examined the stability of facial attractiveness of individuals across different stages of development. We conducted a study examining the relationship between facial attractiveness in infants (age 24 months and under) and the same individuals as young adults (age 16–18 years) using infant and adult photographs from high school yearbooks. Contrary to expectations, independent raters’ assessments of infant facial attractiveness did not correlate with adult facial attractiveness. These results are discussed in terms of the adaptive function of heightened attractiveness in infancy, which likely evolved to elicit and maintain parental care.     

Preschoolers' use of dynamic facial, bodily, and vocal cues to emotion

In daily experience, children have access to a variety of cues to others’ emotions, including face, voice, and body posture. Determining which cues they use at which ages will help to reveal how the ability to recognize emotions develops. For happiness, sadness, anger, and fear, preschoolers (3-5 years, N = 144) were asked to label the emotion conveyed by dynamic cues in four cue conditions. The Face-only, Body Posture-only, and Multi-cue (face, body, and voice) conditions all were well recognized (M > 70%). In the Voice-only condition, recognition of sadness was high (72%), but recognition of the three other emotions was significantly lower (34%).     

The role of Theory of Mind in assessing cooperative intentions

Folk wisdom indicates that people vary in the extent to which they can assess others’ cooperative intentions. In two studies we investigated whether Theory of Mind (ToM), the ability to represent mental states of others, is related to accuracy in the recognition of cooperativeness. Participants completed a ToM task and were asked to assess either video clips of people playing a variation of a Prisoner’s Dilemma (PD) game (Study 1, N = 88), or photographs of people playing PD taken at the very moment when they were expressing a decision to cooperate or to defect (Study 2, N = 99). We found relationships between ToM and cooperative intention recognition only in Study 1, when participants were exposed to long versions of the video clips. In contrast to previous reports, participants in our samples did not score higher than chance in cooperativeness assessment except for Study 1 in the condition with short video clips. Our results question human expertise at identifying defectors and cooperators and do not provide clear support for an association between ToM and cooperativeness assessment. The findings are discussed from the perspective of an evolutionary arms race between interpreting and masking cooperative intentions.     

Facial affect recognition deficits: A potential contributor to aggression in psychotic illness

The current literature suggests a relationship between psychosis and the likelihood of engaging in aggressive behavior, though the factors involved are unclear. In this paper we use a social information processing framework to consider mediators of aggressive behavior in psychosis, especially facial affect recognition (FAR) deficits. The theoretical underpinnings of aggressive behavior are explored using the General Aggression Model (GAM) and FAR deficits are posited as a possible contributor to increased aggression in psychosis. Current research investigating the relationship between FAR, psychosis, and aggression is critically examined, and the role of potential confounding variables including positive symptoms, psychopathic personality traits, childhood trauma, and substance use briefly explored. In conclusion, we argue that socioemotional processing deficits, such as impaired FAR, are a fruitful area for research aimed at understanding, and hence reducing the risk of violence in psychosis.     

No trust on the left side: Hemifacial asymmetries for trustworthiness and emotional expressions

People can discriminate cheaters from cooperators by their appearance. However, successful cheater detection can be thwarted by a posed smile, which cheaters display with greater emotional intensity than cooperators. The present study investigated the underlying neural and cognitive mechanisms of a posed smile, which cheaters use to conceal their anti-social attitude, in terms of hemifacial asymmetries of emotional expressions. Raters (50 women and 50 men) performed trustworthiness judgments on composite faces of cheaters and cooperators, operationally defined by the number of deceptions in an economic game. The left–left composites of cheaters were judged to be more trustworthy than the right–right composites when the models posed a happy expression. This left-hemiface advantage for the happy expression was not observed for cooperators. In addition, the left-hemiface advantage of cheaters disappeared for the angry expression. These results suggest that cheaters used the left hemiface, which is connected to the emotional side of the brain (i.e., the right hemisphere), more effectively than the right hemiface to conceal their anti-social attitude.     

How children with facial differences are perceived by non-affected children and adolescents: Perceiver effects on stereotypical attitudes

Children with a facial difference are presumed to be at risk of social stigmatization. The purposes of this study were twofold: (1) to assess the effect of facial differences on social perceptions by unaffected children and adolescents; and (2) to identify perceiver characteristics that predict stereotypical attitudes toward facial differences. Participants were 344 non-affected children and adolescents, ages 8–17 years. Participants rated digitally altered images of 12 children depicted either with or without a facial difference. Results show that participants attributed less favorable characteristics to children with a facial difference than to those without. Moreover, participants reported less willingness to interact with or befriend a child with a facial difference. Significant predictors of low discriminative attitudes were older participant age and previous contact with someone with a facial difference. Our data call attention to the need for public education programs targeted at reducing negative attitudes toward facial differences.     

Left-view sequences of faces are superior to right-view ones for view generalization

Faces learned from multiple viewpoints are recognized better with left than right three-quarter views. This left-view superiority could be explained by perceptual experience, facial asymmetry, or hemispheric specialization. In the present study, we investigated whether left-view sequences are also more effective in recognizing same and novel views of a face. In a sequential matching task, a view sequence showing a face rotating around a left (?30°) or a right (+30°) angle, with an amplitude of 30°, was followed by a static test view with the same viewpoint as the sequence (?30° or +30°) or with a novel one (0°, +30°, or ?30°). We found a superiority of left-view sequences independently of the test viewpoint, but no superiority of left over right test views. These results do not seem compatible with the perceptual experience hypothesis, which predicts superiority only for left-side test views (?30°). Also, a facial asymmetry judgement task showed no correlation between the asymmetry of individual faces and the left-view sequence superiority. A superiority of left-view sequences for novel as well as same test views argues in favour of an explanation by hemispheric specialization, because of the possible role of the right hemisphere in extracting facial identity information.     

Spatial compatibility interference effects: a double dissociation between two measures

ABSTRACT

In spatial compatibility tasks, when the spatial location of a stimulus is irrelevant it nevertheless interferes when a response is required in a different spatial location. For example, response with a left key-press is slowed when the stimulus is presented to the right as compared to the left side of a computer screen. However, in some conditions this interference effect is not detected in reaction time (RT) measures. It is typically assumed that the lack of effect means the irrelevant spatial code was not analysed or that the information rapidly decayed before response. However, we show that even in conditions where there appears to be no spatial interference when measuring RTs, effects can nevertheless be detected after response when recording facial electromyography responses. This dissociation between two measures highlights the importance of diverging methods to investigate visuomotor processes as conclusions based on only one measure can be misleading.     

Faces as perceptual wholes: The interplay between component and configural properties in face processing

The relative dominance of component and configural properties in face processing is a controversial issue. We examined this issue by testing whether the discriminability of components predicts the discrimination of faces with similar versus dissimilar configurations. Discrimination of faces with similar configurations was determined by components discriminability, indicating independent processing of facial components. The presence of configural variation had no effect on discriminating faces with highly discriminable components, suggesting that discrimination was based on the components. The presence of configural variation, however, facilitated the discrimination of faces with more difficult-to-discriminate components, above and beyond what would be predicted by the configural or componential discriminability, indicating interactive processing. No effect of configural variation was observed in discriminating inverted faces. These results suggest that both component and configural properties contribute to the processing of upright faces and no property necessarily dominates the other. Upright face discrimination can rely on components, configural properties, or interactive processing of component and configural properties, depending on the information available and the discriminability of the properties. Inverted faces are dominated by componential processing. The finding that interactive processing of component and configural properties surfaced when the properties were of similar, not very high discriminability, suggests that such interactive processing may be the dominant form of face processing in everyday life.