The Relationship between Motor Performance and the Broad Autism Phenotype When Performing Movements of Varying Complexity

Background: For effective social communication, we must proficiently interpret and use body language, which illustrates the link between social and motor behaviour. The proficiency of these skills progress based on an individual’s experiences and interactions.

Objectives: The purpose of this study was to investigate the relationship between motor behaviour and self-reported social communication skills of individuals without a diagnosed psychological or physical condition using the Broad Autism Phenotype Questionnaire (BAPQ).

Methods: Twenty-four individuals without autism spectrum disorder were recruited. Each participant completed the BAPQ (measuring rigidity, aloofness, and pragmatic language) and a motor task. During the motor task, participants were asked to look at, make a button-press, or point to one of two pictures of animals that appeared with an 18° visual angle on the left and right sides of a computer monitor (CNE, Gainesville, FL; resolution 1920x1080 pixels, refresh rate = 60Hz). The target image was indicated by either an auditory (sound of the animal) or a visual (matching picture located central on the screen) cue. The dependent variables were mean and standard deviation of the reaction time (RT) and movement time (MT) of the saccade and hand movements. Gaze behaviour was sampled using the Eyelink1000plus eye-tracker (SR Research Ltd., Ottawa, ON) at 500Hz. Hand movements were recorded using custom built micro-switches that acted as home switches/buttons. A series of simple regression analyses were used within participants to examine the relationship between motor performance in the six conditions (2 sensory modalities by 3 motor tasks) and the BAPQ subscale scores.

Results: Overall, the analysis for motor planning demonstrated that the look conditions were the most challenging (i.e. longest RTs) for participants, and the auditory look condition was significantly more challenging than the visual look condition. The following results are presented by the three BAPQ subscales: (1) Rigidity was positively correlated with saccade RT during the auditory look condition (R²=0.398), suggesting that individuals with higher rigidity experienced increased cognitive stress during this challenging task affecting their efficiency to create and carry out a motor plan. (2) Aloof behaviour was positively correlated with the variability of saccade RT during the auditory point condition (R²=0.167), suggesting that more aloof individuals are less practiced in this type of multisensory (social communication) action. (3) Pragmatic language was negatively correlated with mean hand RT during the auditory point (R²=0.311), the visual button-press (R²=0.283), and the visual point (R²=0.398) conditions, and negatively correlated with mean saccade MT during the visual button-press (R²=0.277) and visual point (R²=0.179) conditions. The latter findings suggest that individuals with higher pragmatic language scores (i.e. those less confidence in social verbal skills) attend better to visual information during eye-hand coordinated tasks.

Conclusions: The present study demonstrates explicit relationships between self-report social communication skills and motor performance. Specifically, auditory tasks were more difficult for rigid and aloof individuals and visual tasks were easier for individuals with higher pragmatic language scores (i.e. less confidence in pragmatic language skills). Results from these studies may inform new therapies targeting eye-hand coordination performance using auditory stimuli.