Peripheral arterial tone as an on-line measure of flight load.

We investigated variations in continuous and discrete flight demands in a simulated flight mission employing a novel physiological measure of invested effort, Peripheral Arterial Tone (PAT). Twelve male subjects performed a computer-simulated agricultural flight task. They were required to fly over a specific lane of a field (continuous task) and change lanes in response to flags, which were presented at varying intervals (discrete task). The difficulty of the flight task was manipulated by changing the plane control (single- vs. dual-axis control), while the difficulty associated with the discrete events was manipulated byvarying the amount of lateral change signalled by the flag (no change vs. 1.5 or 3 lanes of change). PAT amplitude values were lower in the difficult level of the continuous task and was further attenuated following the appearance of the flag whena change in the flight position was required.