Identifying Patterns of Similarities and Differences between Gesture Production and Comprehension in Autism and Typical Development

Production and comprehension of gesture emerge early and are key to subsequent language development in typical development. Compared to typically developing (TD) children, children with autism spectrum disorders (ASD) exhibit difficulties and/or differences in gesture production. However, we do not yet know if gesture production either shows similar patterns to gesture comprehension across different ages and learners, or alternatively, lags behind gesture comprehension, thus mimicking a pattern akin to speech comprehension and production. In this study, we focus on the gestures produced and comprehended by a group of young TD children and children with ASD—comparable in language ability—with the goal to identify whether gesture production and comprehension follow similar patterns between ages and between learners. We elicited production of gesture in a semi-structured parent–child play and comprehension of gesture in a structured experimenter-child play across two studies. We tested whether young TD children (ages 2–4) follow a similar trajectory in their production and comprehension of gesture (Study 1) across ages, and if so, whether this alignment remains similar for verbal children with ASD (Mage = 5 years), comparable to TD children in language ability (Study 2). Our results provided evidence for similarities between gesture production and comprehension across ages and across learners, suggesting that comprehension and production of gesture form a largely integrated system of communication.

Differences in the production and perception of communicative kinematics in autism

In human communication, social intentions and meaning are often revealed in the way we move. In this study, we investigate the flexibility of human communication in terms of kinematic modulation in a clinical population, namely, autistic individuals. The aim of this study was twofold: to assess 1) whether communicatively relevant kinematic features of gestures differ between autistic and neurotypical individuals, and 2) if autistic individuals use communicative kinematic modulation to support gesture recognition. We tested autistic and neurotypical individuals on a silent gesture production task and a gesture comprehension task. We measured movement during the gesture production task using a Kinect motion tracking device in order to determine if autistic individuals differed from neurotypical individuals in their gesture kinematics. For the gesture comprehension task, we utilized stick-light figures as stimuli and, by testing for a correlation between the kinematics of these videos and recognition performance, we assessed whether autistic individuals used communicatively relevant kinematic cues to support recognition. We found that 1) silent gestures produced by autistic and neurotypical individuals differ in communicatively relevant kinematic features, such as the number of meaningful holds between movements, and 2) while autistic individuals are overall unimpaired at recognizing gestures, they processed repetition and complexity, measured as the amount of submovements perceived, different than neurotypicals do. These findings highlight how subtle aspects of neurotypical behavior can be experienced differently by autistic individuals, and demonstrate the relationship between movement kinematics and social interaction in high-functioning autistic individuals.

How our hands shape our minds: Six developmental pathways

In the current, empirically grounded paper, we first explore the ways in which manual actions, that is actions performed with hands and arms such as reaching, grasping, and manipulating objects, shape the mind. Based on recent empirical research, we suggest six embodied developmental pathways which solve unique challenges faced by infants and children during development. I) Co-opted motor simulation allows action anticipation, II) interactive specialisation allows executive control to emerge from reaching and grasping. III) Active exploration and IV) error based-learning facilitate cognition and perception. Action based social interactions facilitate V) language development and VI) gesture comprehension. These pathways exemplify how manual actions and the underlying neural processes controlling actions are used by the infant to structure the world and develop cognitive capacities and learn from interactions with the physical and social world. Through an individual difference, correlational approach, we note that these abilities and processes measured in infancy have long-term associations with cognitive and perceptual development into childhood and beyond.

The role of conflict, feedback, and action comprehension in monitoring of action errors: Evidence for internal and external routes

The mechanisms and brain regions underlying error monitoring in complex action are poorly understood, yet errors and impaired error correction in these tasks are hallmarks of apraxia, a common disorder associated with left hemisphere stroke. Accounts of monitoring of language posit an internal route by which production planning or competition between candidate representations provide predictive signals that monitoring is required to prevent error, and an external route in which output is monitored using the comprehension system. Abnormal reliance on the external route has been associated with damage to brain regions critical for sensory-motor transformation and a pattern of gradual error ‘clean-up’ called conduite d’approche (CD). Action pantomime data from 67 participants with left hemisphere stroke were consistent with versions of internal route theories positing that competition signals monitoring requirements. Support Vector Regression Lesion Symptom Mapping (SVR-LSM) showed that lesions in the inferior parietal, posterior temporal, and arcuate fasciculus/superior longitudinal fasciculus predicted action conduite d’approche, overlapping the regions previously observed in the language domain. A second experiment with 12 patients who produced substantial action CD assessed whether factors impacting the internal route (action production ability, competition) versus external route (vision of produced actions, action comprehension) influenced correction attempts. In these ‘high CD’ patients, vision of produced actions and integrity of gesture comprehension interacted to determine successful error correction, supporting external route theories. Viewed together, these and other data suggest that skilled actions are monitored both by an internal route in which conflict aids in detection and correction of errors during production planning, and an external route that detects mismatches between produced actions and stored knowledge of action appearance. The parallels between language and action monitoring mechanisms and neuroanatomical networks pave the way for further exploration of common and distinct processes across these domains.

Gestural modality and addressee perspective influence how we reason about time

A growing body of literature has established that spatiotemporal metaphoric reasoning processes can be affected by the active experience of motion (such as actual motion, fictive motion, and abstract motion). In this study, the effects of metaphoric gestures on spatiotemporal metaphor use and the effects of addressee perspective on comprehension of these gestures are investigated. Participants were asked an ambiguous question that yields different responses depending on which metaphor variant is used. This question was asked with simultaneously produced metaphoric gestures depicting either sagittal or lateral motion and presented to participants either in shared perspective (side by side) or opposing (face to face) perspective. Findings suggest that not only does gesture influence metaphoric reasoning in discourse interpretation, but that addressees reliably interpret gestures from their own perspective, even when it is not shared with the speaker. Furthermore, conversational bystanders similarly adopt the perspective of the addressee in gesture comprehension.

The Role of Embodiment and Individual Empathy Levels in Gesture Comprehension

Research suggests that the action-observation network is involved in both emotional-embodiment (empathy) and action-embodiment (imitation) mechanisms. Here we tested whether empathy modulates action-embodiment, hypothesizing that restricting imitation abilities will impair performance in a hand gesture comprehension task. Moreover, we hypothesized that empathy levels will modulate the imitation restriction effect. One hundred twenty participants with a range of empathy scores performed gesture comprehension under restricted and unrestricted hand conditions. Empathetic participants performed better under the unrestricted compared to the restricted condition, and compared to the low empathy participants. Remarkably however, the latter showed the exactly opposite pattern and performed better under the restricted condition. This pattern was not found in a facial expression recognition task. The selective interaction of embodiment restriction and empathy suggests that empathy modulates the way people employ embodiment in gesture comprehension. We discuss the potential of embodiment-induced therapy to improve empathetic abilities in individuals with low empathy.