Joint Effects of Nonverbal Accuracy and Nonverbal Processing Speed on Social Functioning among Children with Autism-Spectrum Disorders and Their Typically-Developing Peers

Background: Nonverbal accuracy, or the ability to infer others’ emotions from nonverbal cues such as facial expressions, is an important contributor to social success. In naturalistic settings, nonverbal cues are displayed quickly and change rapidly. However, the speed with which children encode nonverbal information about others’ emotions is an under-studied area. As yet, for example, it is unknown whether children with autism-spectrum disorders (ASDs) process nonverbal information at the same pace as their typically-developing (TD) peers. It is also unknown whether nonverbal processing speed explains a significant increment in the variance of children’s social functioning, over and above nonverbal accuracy.  Objectives: The objective of this study is to examine the relationship between nonverbal accuracy, nonverbal processing speed, and social functioning among ASD and TD children. We hypothesize that ASD children will score lower on measures of nonverbal accuracy and process nonverbal cues more slowly than their TD peers. We also hypothesize that nonverbal processing speed will predict a significant increment in teacher-reported social functioning, over and above nonverbal accuracy alone. Methods: A total of 160 TD children and 20 children with ASDs ages 5 to 14 completed multiple tests of affect recognition. Accuracy and processing speed (reaction time) were recorded. Regression procedures were used with the TD sample to estimate expected means for accuracy and reaction time at each age. In addition, expected variability around those regression estimates was computed. The distance in standard deviations from the expected mean for each child's age was then calculated. Results: Children with ASDs process nonverbal information more slowly than their TD peers. In addition, the relationship between nonverbal accuracy and teacher-reported social functioning depends on nonverbal processing speed. Specifically, children who process nonverbal information slowly and inaccurately are substantially less well-liked than children in possession of nonverbal processing speed, nonverbal accuracy, or both. Overall, nonverbal accuracy, nonverbal processing speed, and an accuracy by speed interaction term explain significantly more variance in social functioning than nonverbal accuracy alone. Conclusions: Nonverbal processing speed plays an important role in social functioning and is impaired among children with ASDs. Further attention to this dimension of nonverbal processing is needed.