Temporal judgements of internal and external events in persons with and without autism.

When participants make judgments about the onset of self-initiated movements they typically report the movement occurred earlier than it had [Obhi, S. S., & Haggard, P. (2004). Free will and free won't. American Scientific, 92, 358-365.]. One interpretation is that feed-forward processes lead to awareness of the movement prior to execution. Because individuals with autism experience reduced preparatory activity prior to a voluntary movement, the present study sought to determine whether these anticipatory biases are exhibited by persons with autism. Participants watched a dot move in a circle and pressed the spacebar any time after one revolution. A tone either followed the participants' voluntary movement or was computer generated. Participants in both groups made anticipatory judgements regarding movement initiation ( approximately 100 ms). When the movement and tone occurred together this anticipatory bias was also present, regardless of which event participants focused on. Individuals with autism appear to have access to a similar representation of voluntary movements, however this representation may be more variable.