Enhanced local processing of dynamic visual information in autism: evidence from speed discrimination

An important issue for understanding visual perception in autism concerns whether individuals with this neurodevelopmental disorder possess an advantage in processing local visual information, and if so, what is the nature of this advantage. Perception of movement speed is a visual process that relies on computation of local spatiotemporal signals but requires the comparison of information from more than a single spatial location or temporal point. This study examined speed discrimination in adolescents (ages 13-18 years old) with autism spectrum disorders (ASD). Compared to healthy controls (n=17), individuals with ASD (n=19) showed similarly precise speed discrimination when two comparison motion stimuli (random dot patterns) were presented closely in time (0.5s). With a longer temporal interval (3s) between the motion stimuli, individuals with ASD outperformed healthy controls on speed discrimination. On a second task--global motion perception--in which individuals were asked to detect coherent motion, individuals with ASD exhibited slightly degraded performance levels. The observed temporally selective enhancement in speed discrimination indicates that a local processing advantage in autism develops over a longer temporal range and is not limited to the spatial domain. These results suggest a dynamic perceptual mechanism for understanding, and therapeutically addressing, atypical visual processing in this neurodevelopmental disorder.