In response to a previous article proposing perceptual reinforcement of stereotyped movements in autistic and mentally retarded persons, it is argued that this theory fails to take into account biological findings and theory regarding pathological stereotyped acts. An alternative theory derived from neurological concepts is suggested. (Author/DB)

The authors respond to criticism of their paper proposing a perceptual reinforcement of stereotyped movements in autistic and mentally retarded persons. The alternative theory based on neurobiological factors is judged to be insufficiently detailed and inadequate in scope. (Author/DB)

Visual analysis is examined as the dominant analytical method for single-case time series, in a study with 37 postgraduate research students which varied serial dependence, amount of random variability, and effect size. False alarm rates were high, but miss rates were low, indicating that visual analysts are not conservative judges, and serial…