Comparison between Face and Object Processing in Youths with Autism Spectrum Disorder: An event related potentials study

Abstract

Objective: Incapability in face perception and recognition is one of the main issues in autism spectrum disorders (ASD). Event related potential (ERP) studies have revealed controversial insights on autistic brain responses to faces and objects. The current investigation examined the ERP components of young children with ASD compared to a typically developing (TD) group when looking at the upright and inverted images of faces and cars.

Methods: Fourteen children and adolescents aged between 9 and 17 diagnosed as having ASD were compared with 18 age- gender matched normally developing individuals. All participants' ERPs were recorded while they were seeing the images of human faces and objects in both upright and inverted positions. The ERP components including N170 (latency and amplitude) were compared between the two groups in two conditions of upright and inverted using the repeated measure analysis method.

Results: The processing speed for upright faces was faster than the inverted faces in the TD group; however, the difference was not significant. A significant difference was observed in terms of N170 latency between the two groups for different stimulus categories such as objects and faces(p<0.05). Moreover, inverted vs. upright stimuli in both groups elicited a greater response in terms of N170 amplitude in both groups, and this effect was significantly prominent in the right hemisphere (p<0.05). The N170 amplitude turned out to be greater for the inverted vs. upright stimuli irrespective of the stimuli type and group.

Conclusion: These data suggest youths with ASD have difficulty processing information, particularly in face perception regardless of the stimuli orientation.

Keywords: Autism; N170; event related potentials; face; object.

Figure 1

Waveforms for ASD and TD groups averaged across the P7, P8 electrodes in each hemisphere. This figure depicts the grand average across all subjects in each group for upright faces, upright cars, inverted faces, and inverted cars. Vertical line shows amplitude (μV) and horizontal line shows time (second).