"This study was designed to investigate the relationship between amount of transfer of skill in two-dimensional tracking and degree of physical similarity between training and test control sensitivity when the display was interrupted periodically during both training and test. Interrupting the display simulated the situation in which the operator is forced to divert his attention from tracking to perform other tasks. The general procedure was as follows. Groups of subjects were trained with one or the other of two control-display (C/D) ratios. Following training, all groups were tested while using the lower ratio (more sensitive control). In Experiment I, two groups were employed under conditions of interrupted display. In Experiment II, these groups were replicated and an additional two groups with non-interrupted tracking signals were employed. In both experiments, tracking performance during training was adversely affected by the higher sensitivity control and interruptions ; but, while interruptions lowered tracking performance during test, none of the transferred groups were inferior to their control groups Thus, tracking with an interrupted display apparently is not more sensitive to differential transfer effects attributable to differences in control sensitivity than is tracking with a continuous display, as used in previous studies. These results are compatible with the notion that the general features of a task are learned in early practice and only later, unique aspects ere learned from which differential transfer effects may result."--Abstract.