The role of human movement kinematics in internal state inference

The kinematics of our movements reflect our internal (mental and affective) states. This thesis tests the hypothesis that these kinematic signals contribute to judgments about others’ internal states through models based on our own actions. Chapter 1 details the theoretical background and previous literature that motivates this hypothesis. Chapter 2 (typical adults) and 3 (typical adolescents) test the hypothesis that we use models of our own action kinematics to make judgments about others’ affective states. Both experiments support the hypothesis by demonstrating that differences in one’s own typical action kinematics determine the perceived intensity of affective states of observed point-light walkers. Chapters 4, 5, and 6 examine the hypothesis that atypical movement kinematics in autism spectrum disorder (autism) contribute to social communication difficulties. Chapters 4 and 5 measure two basic skills required to make internal state judgments from observing others’ actions: visual time perception and sensitivity to kinematic signals that describe ‘natural’ motion. Both studies find no deficits in the autism group compared to the typically developed group – and some enhanced abilities – suggesting that these basic skills are intact. However, Chapter 6 demonstrates that typically developed individuals are impaired at reading mental states from autistic actions, suggesting that atypical movement kinematics may be partly contributing to bi-directional communicative difficulties experienced between individuals with autism and their typical peers. Chapter 7 investigates whether differences in movement kinematics early in development are associated with later social skills in a group of infants at high- or low-risk of developing autism. Indeed, movement kinematics at 10 months of age predicts social abilities at 14 months of age, demonstrating the value of kinematic markers for predicting social functioning and possibly disorder. Chapter 8 summarises the studies presented in this thesis, which show support for the hypothesis that we judge others’ internal states through models based on our own actions

The role of human movement kinematics in internal state inference

The kinematics of our movements reflect our internal (mental and affective) states. This thesis tests the hypothesis that these kinematic signals contribute to judgments about others’ internal states through models based on our own actions. Chapter 1 details the theoretical background and previous literature that motivates this hypothesis. Chapter 2 (typical adults) and 3 (typical adolescents) test the hypothesis that we use models of our own action kinematics to make judgments about others’ affective states. Both experiments support the hypothesis by demonstrating that differences in one’s own typical action kinematics determine the perceived intensity of affective states of observed point-light walkers. Chapters 4, 5, and 6 examine the hypothesis that atypical movement kinematics in autism spectrum disorder (autism) contribute to social communication difficulties. Chapters 4 and 5 measure two basic skills required to make internal state judgments from observing others’ actions: visual time perception and sensitivity to kinematic signals that describe ‘natural’ motion. Both studies find no deficits in the autism group compared to the typically developed group – and some enhanced abilities – suggesting that these basic skills are intact. However, Chapter 6 demonstrates that typically developed individuals are impaired at reading mental states from autistic actions, suggesting that atypical movement kinematics may be partly contributing to bi-directional communicative difficulties experienced between individuals with autism and their typical peers. Chapter 7 investigates whether differences in movement kinematics early in development are associated with later social skills in a group of infants at high- or low-risk of developing autism. Indeed, movement kinematics at 10 months of age predicts social abilities at 14 months of age, demonstrating the value of kinematic markers for predicting social functioning and possibly disorder. Chapter 8 summarises the studies presented in this thesis, which show support for the hypothesis that we judge others’ internal states through models based on our own actions

Association between action kinematics and emotion perception across adolescence

Research with adults suggests that we interpret others’ internal states from kinematic cues, using models calibrated to our own action experiences. Changes in action production that occur during adolescence may therefore have implications for adolescents’ understanding of others. Here we examined whether, like adults, adolescents use velocity cues to determine others’ emotions, and whether any emotion perception differences would be those predicted based on differences in action production. We measured preferred walking velocity in groups of Early (11-12 years old), Middle (13-14 years old) and Late (16-18 years old) adolescents, and adults, and recorded their perception of happy, angry and sad ‘point-light walkers’. Preferred walking velocity decreased across age and ratings of emotional stimuli with manipulated velocity demonstrated that all groups used velocity cues to determine emotion. Importantly, the relative intensity ratings of different emotions also differed across development in a manner that was predicted based on the group differences in walking velocity. Further regression analyses demonstrated that emotion perception was predicted by own movement velocity, rather than age or pubertal stage per se. These results suggest that changes in action production across adolescence are indeed accompanied by corresponding changes in how emotions are perceived from velocity. These findings indicate the importance of examining differences in action production across development when interpreting differences in understanding of others

Our own action kinematics predict the perceived affective states of others.

Our movement kinematics provideuseful cues aboutour affective states. Given that our experiences furnish models that help us to interpret our environment, and that a rich source of action experience comes from our own movements,the present study examined whetherwe use models of our own action kinematics to make judgments about the affective states of others. For example,relative to one’s typical kinematics, anger isassociated with fast movements. Therefore, the extent to which we perceive angerin others maybe determined by the degreeto which their movementsare faster than our own typicalmovements. We related participants’walking kinematicsin a neutral contextto their judgments of the affective statesconveyed byobserved point-light walkers(PLWs). Aspredicted,we found a linear relationship between one’s own walking kinematics and affective state judgments, such that faster participants rated sloweremotionsmore intensely relative to their ratings for faster emotions. This relationship was absent when observing PLWs where differences in velocity between affective states were removed. These findings suggest that perception of affective states in others is predicted by one’s own movement kinematics, withimportant implications for perception of, and interaction with,those who move differentl

Atypical emotion recognition from bodies is associated with perceptual difficulties in healthy aging.

A range of processes are required for recognizing others’ affective states. It is particularly important that we process the perceptual cues providing information about these states. These experiments tested the hypothesis that difficulties with affective state identification in older adults (OAs) arise, at least partly, from deficits in perceptual processing. To this end we presented “point light display” whole body stimuli to healthy OAs and comparison younger adults (YAs) in 3 signal detection experiments. We examined the ability of OAs to recognize visual bodily information—posture and kinematics—and whether impaired recognition of affective states can be explained by deficits in processing these cues. OAs exhibited reduced sensitivity to postural cues (Experiment 1) but not to kinematic cues (Experiment 2) in affectively neutral stimuli. Importantly, they also exhibited reduced sensitivity only to affective states conveyed predominantly through posture (Experiment 3) —that is, the cue they were impaired in perceiving. These findings highlight how affective state identification difficulties in OAs may arise from problems in perceptual processing and demonstrate more widely how it is essential to consider the contribution of perceptual processes to emotion recognition. (APA PsycInfo Database Record (c) 2019 APA, all rights reserved

Interaction takes two: typical adults exhibit mind-blindness towards those with Autism Spectrum Disorder

Recent work suggests that we are better at interpreting the movements of others who move like us, and that individuals with Autism Spectrum Disorder (ASD) move in a quantifiably different way from typical individuals. Therefore, ‘social impairments’ exhibited by individuals with ASD may, at least in part, represent a failure by typical individuals to infer the correct mental states from the movements of those with ASD. To examine this possibility, individuals with ASD and typical adults manually directed two triangles to generate animations depicting mental state interactions. Kinematic analysis of the generated animations demonstrated that the participants with ASD moved atypically, specifically with increased jerk compared to the typical participants. In confirmation of our primary hypothesis, typical individuals were better able to identify the mental state portrayed in the animations produced by typical, relative to autistic individuals. The participants with ASD did not show this ‘same group’ advantage, demonstrating comparable performance for the two sets of animations. These findings have significant implications for clinical assessment and intervention in ASD, and potentially other populations with atypical movement

Time on your hands: Perceived duration of sensory events is biased toward concurrent actions

Perceptual systems must rapidly generate accurate representations of the world from sensory inputs that are corrupted by internal and external noise. We can typically obtain more veridical representations by integrating information from multiple channels, but this integration can lead to biases when inputs are, in fact, not from the same source. Although a considerable amount is known about how different sources of information are combined to influence what we perceive, it is not known whether temporal features are combined. It is vital to address this question given the divergent predictions made by different models of cue combination and time perception concerning the plausibility of cross-modal temporal integration, and the implications that such integration would have for research programs in action control and social cognition. Here we present four experiments investigating the influence of movement duration on the perceived duration of an auditory tone. Participants either explicitly (Experiments 1–2) or implicitly (Experiments 3–4) produced hand movements of shorter or longer durations, while judging the duration of a concurrently presented tone (500–950 ms in duration). Across all experiments, judgments of tone duration were attracted toward the duration of executed movements (i.e., tones were perceived to be longer when executing a movement of longer duration). Our results demonstrate that temporal informa-tion associated with movement biases perceived auditory duration, placing important constraints on theories modeling cue integration for state estimation, as well as models of time perception, action control and social cognition

Atypical emotion recognition from bodies is associated with perceptual difficulties in healthy aging

A range of processes are required for recognizing others’ affective states. It is particularly important that we process the perceptual cues providing information about these states. These experiments tested the hypothesis that difficulties with affective state identification in older adults (OAs) arise, at least partly, from deficits in perceptual processing. To this end we presented ‘point light display’ whole body stimuli to healthy OAs and comparison younger adults (YAs) in three signal detection experiments. We examined the ability of OAs to recognize visual bodily information – posture and kinematics – and whether impaired recognition of affective states can be explained by deficits in processing these cues. OAs exhibited reduced sensitivity to postural cues (Experiment 1) but not to kinematic cues (Experiment 2) in affectively-neutral stimuli. Importantly, they also exhibited reduced sensitivity only to affective states conveyed predominantly through posture (Experiment 3) – i.e., the cue they were impaired in perceiving. These findings highlight how affective state identification difficulties in OAs may arise from problems in perceptual processing, and demonstrate more widely how it is essential to consider the contribution of perceptual processes to emotion recognition

Typical auditory-motor and enhanced visual-motor temporal synchronization in adults with Autism Spectrum Disorder

The perception of subsecond durations in adults with Autism Spectrum Disorder (hereafter ‘autism’; n=25 Experiment 1, n=21 Experiment 2) and matched typical adults (n=24 Experiment 1, n=22 Experiment 2) was examined by requiring participants to perform an action in time with auditory (Experiment 1) or visual (Experiment 2) events. Individuals with autism performed comparably to typical participants in the auditory task and exhibited less temporal error relative to their typical counterparts in the visual task. These findings suggest that perception of subsecond intervals is intact in autism, if not enhanced. Results support recent Bayesian theories of enhanced visual-perceptual precision in people with autism, and extend empirical support into the precision of subsecond temporal estimates

Association between action kinematics and emotion perception across adolescence

Research with adults suggests that we interpret others’ internal states from kinematic cues, using models calibrated to our own action experiences. Changes in action production that occur during adolescence may therefore have implications for adolescents’ understanding of others. Here we examined whether, like adults, adolescents use velocity cues to determine others’ emotions, and whether any emotion perception differences would be those predicted based on differences in action production. We measured preferred walking velocity in groups of Early (11-12 years old), Middle (13-14 years old) and Late (16-18 years old) adolescents, and adults, and recorded their perception of happy, angry and sad ‘point-light walkers’. Preferred walking velocity decreased across age and ratings of emotional stimuli with manipulated velocity demonstrated that all groups used velocity cues to determine emotion. Importantly, the relative intensity ratings of different emotions also differed across development in a manner that was predicted based on the group differences in walking velocity. Further regression analyses demonstrated that emotion perception was predicted by own movement velocity, rather than age or pubertal stage per se. These results suggest that changes in action production across adolescence are indeed accompanied by corresponding changes in how emotions are perceived from velocity. These findings indicate the importance of examining differences in action production across development when interpreting differences in understanding of others