I thank Eric Courchesne of the Autism and Brain Development Research Laboratory for providing facilities and financial support for part of this work, and, more importantly, for his friendship which spanned most of my time in San Diego. I also thank Steve Hillyard for productive discussions on his and my work on attentional modulation of the SSVEP, Brian Egaas and Greg Allen for advice and friendship, and Robert Ringrose of the MIT Artificial Intelligence Laboratory for providing computing facilities for the latter part of this work. Insightful comments from an anonymous reviewer were helpful during revision of this paper.