Anomalous Perception of Biological Motion in Autism: A Conceptual Review and Meta-Analysis

Abstract

Despite its popularity, the construct of biological motion (BM) and its putative anomalies in autism spectrum disorder (ASD) are not completely clarified. In this article, we present a meta-analysis investigating the putative anomalies of BM perception in ASD. Through a systematic literature search, we found 30 studies that investigated BM perception in both ASD and typical developing peers by using point-light display stimuli. A general meta-analysis including all these studies showed a moderate deficit of individuals with ASD in BM processing, but also a high heterogeneity. This heterogeneity was explored in different additional meta-analyses where studies were grouped according to levels of complexity of the BM task employed (first-order, direct and instrumental), and according to the manipulation of low-level perceptual features (spatial vs. temporal) of the control stimuli. Results suggest that the most severe deficit in ASD is evident when perception of BM is serving a secondary purpose (e.g., inferring intentionality/action/emotion) and, interestingly, that temporal dynamics of stimuli are an important factor in determining BM processing anomalies in ASD. Our results question the traditional understanding of BM anomalies in ASD as a monolithic deficit and suggest a paradigm shift that deconstructs BM into distinct levels of processing and specific spatio-temporal subcomponents.

Figure 1

Flow diagram of the selection of studies included in the current meta-analysis. The number of studies included or excluded at each step of the evaluation process is indicated in each of the diagram boxes.

Figure 2

(A) Forest plot of the differences in the BM performance between the ASD and TD groups. Positive values indicate a better performance for the TD group as compared to the performance of the ASD group. (B) Funnel plot indicating the publication bias in studies of BM processing in ASD vs. TD. White circles represent the missing studies identified by the trim and fill test.

Figure 3

(A) Forest plot of studies investigating the difference in first-order level of BM processing between ASD and TD group. (B) Forest plot of studies investigating the difference in direct level of BM processing between ASD and TD group. (C) Forest plot of studies investigating the difference in instrumental level of BM processing between ASD and TD group. In all plots, positive values indicate a better performance for the TD group as compared to the performance of the ASD group.

Figure 4

(A) Forest plot of studies investigating the difference in BM performance between ASD and TD group that employed spatial scramble stimuli. (B) Forest plot of studies investigating the difference in BM performance between ASD and TD group that employed temporal scramble stimuli. In both plots, positive values indicate a better performance for the TD group as compared to the performance of the ASD group.

Figure 5

Forest plot of studies investigating the difference in the processing of non-BM stimuli between ASD and TD group. Positive values indicate a better performance for the TD group as compared to the performance of the ASD group.