Mentally retarded and nonretarded adults (n=32) performed visual vigilance tests in which single digits were presented at either a fast or slow rate and the rate shifted without warning. Retarded observers detected fewer targets and made more false alarms than did nonretarded observers in all test conditions. (Author/JDD)

Two experiments with five individuals having severe mental retardation identified some problems and limits in training reversals of previously learned discrimination tasks using stimulus control shaping methodology. (DB)