Trust in and use of automation: their dependence on occurrence patterns of malfunctions

The dynamics of trust in and use of automation are shown to depend on the occurrence patterns of malfunctions. Two experiments have been conducted as part of this study. The first experiment compared the effects of two typical occurrence patterns, continuous and discrete. The second experiment analyzed the effects of the combination of the two malfunction occurrence patterns. Several analyses were performed and the following findings were obtained. If continuous malfunctions occur, operator trust is reduced significantly, and eventually the operator does not rely on the automation, even under circumstances that are easy for the automation to handle. The longer the continuity, the longer this effect lasts. In contrast, discrete malfunctioning does not cause a significant decline in the operator's level of trust. A single malfunction or a small number of discrete malfunctions causes that some operators not to rely on the automation when the operation is difficult for the automation. However, the level of trust returns quickly under normal operating conditions. As operators gradually experience more individual malfunctions, they appear to become less sensitive to the malfunctioning.