Samenvatting
Changes in performance at a visual vigilance task over eight 40-minutes sessions were studied in three groups of eight subjects. The task was to inspect a series of displays of small disks for the occasional presence of a disk of slightly-greater area than the others. Substantial improvement in overall detection rate occurred in all three groups. Analysis indicated that in each case this improvement was to due a genuine increase in discriminatory efficiency and not to any change in response criterion.