As part of a research project concerned with the function of the human operator in semi-automated man-machine systems, the monitoring behavior of the operator carrying out a process control task was investigated. More specifically, a study was made of the way this monitoring behavior changes as a result of using new instrument types or different presentation modes on the control panel. In the present experiment, two display variables were used, the first one being continuous or intermittent presentation of the controlled variables. The second display variable was controlling with or without a predictor instrument. Other independent variables were type of control task and first or second half of the control task. Results show that subjects monitored the controlled variables with longer eye fixations if the predictor instrument was not available. Also, the controlled variables were monitored more frequently in the second half of the control task. However, both effects interacted significantly with type of task. These results are interpreted and discussed in relation to control performance and control task difficulty.
