Comparing internal representations of facial expression kinematics between autistic and non‐autistic adults

Abstract

Recent developments suggest that autistic individuals require dynamic angry expressions to have a higher speed in order for them to be successfully identified. Therefore, it is plausible that autistic individuals do not have a ‘deficit’ in angry expression recognition, but rather their internal representation of these expressions is characterised by very high‐speed movement. In this study, matched groups of autistic and non‐autistic adults completed a novel emotion‐based task which employed dynamic displays of happy, angry and sad point light facial (PLF) expressions. On each trial, participants moved a slider to manipulate the speed of a PLF stimulus until it moved at a speed that, in their ‘mind's eye’, was typical of happy, angry or sad expressions. Participants were shown three different types of PLFs—those showing the full‐face, only the eye region, and only the mouth region, wherein the latter two were included to test whether differences in facial information sampling underpinned any dissimilarities in speed attributions. Across both groups, participants attributed the highest speeds to angry, then happy, then sad, facial motion. Participants increased the speed of angry and happy expressions by 41% and 27% respectively and decreased the speed of sad expressions by 18%. This suggests that participants have ‘caricatured’ internal representations of emotion, wherein emotion‐related kinematic cues are over‐emphasised. There were no differences between autistic and non‐autistic individuals in the speeds attributed to full‐face and partial‐face angry, happy and sad expressions respectively. Consequently, we find no evidence that autistic adults possess atypically fast internal representations of anger.

Autistic adults exhibit highly precise representations of others’ emotions but a reduced influence of emotion representations on emotion recognition accuracy

“…Next, to compare the distances between emotion representations across participant groups, we constructed a linear mixed effects model with distance as the dependent variable, emotion pair (angry-happy, angry-sad, happy-sad), group (autistic, non-autistic), the interaction between emotion pair and group [independent variables], age, sex, non-verbal reasoning, and alexithymia [control variables] as predictors, and subject number as a random intercept. In line with the results from our previous study 30 , this analysis found that there was a significant main effect of emotion [F(2,176) = 74.31 p < 0.001]: the distance between angry and sad emotion representations was largest [mean(SEM) = 2.25(0.11)], followed by the distances between angry and happy [mean(SEM) = 1.21(0.09)] and happy and sad [mean(SEM) = 1.14(0.07)] representations. There was no main effect of group [ p = 0.117], nor an interaction between emotion pair and group [ p = 0.317], suggesting that autistic and non-autistic individuals do not significantly differ in the differentiation of visual emotion representations.…”

“…To determine whether there are differences between autistic and non-autistic individuals in these abilities, the current study employed three tasks involving dynamic point light displays of angry, happy and sad facial expressions. The first task was an adapted version of our “ ExpressionMap ” task 17 , 30 , 31 which uses a method of adjustment design. On each trial, participants were required to manipulate a dial to speed-up or slow-down PLF stimuli until they matched their visual representation of anger, happiness, or sadness.…”

“…Although this was an active design choice, motivated by previous research demonstrating a causal role of speed cues in emotion recognition 32 and other a priori hypotheses (see Ref. 30 ), in future work we will develop our paradigms to encompass other spatiotemporal emotion cues. Thus, facilitating comparisons of visual emotion representations between autistic and non-autistic individuals with respect to other cues such as the degree of spatial exaggeration, movement onset/offset, texture and colour.…”

Non‐autistic adults can recognize posed autistic facial expressions: Implications for internal representations of emotion

“…One possibility is that when autistic people produce real (as opposed to posed) expressions, performance factors affect their ability to produce expressions that match their internal representations, making them less recognizable. For example, context, interoceptive or motor difficulties (e.g., Keating et al, 2022), or experiencing more than one emotion simultaneously (e.g., Clore & Ortony, 2013) can influence the production of expressions in the real world.…”

“…Interestingly, another recent study compared an aspect of the internal representations of autistic and non‐autistic people's facial expressions of emotions. In Keating et al (2022), autistic and non‐autistic participants watched point‐light displays of facial expressions of happiness, sadness, and anger produced by non‐autistic actors. Participants adjusted the speed with which the expressions unfolded, until the speed matched their expectation for how quickly faces take on each of the three expressions.…”