Supplementary data for the article: Expectancy or Salience? — Replicating Senders’ Dial-Monitoring Experiments With a Gaze-Contingent Window

Introduction. In the 1950s and 1960, John Senders carried out a number of influential experiments on the monitoring of multidegree-of-freedom systems. In these experiments, participants were tasked to detect events (threshold crossings) for multiple dials, each presenting a different signal with different bandwidth. Senders’ analyses showed a nearlylinear relationship between signal bandwidth and the amount of attention paid to the dial, and he argued that humans sample according to bandwidth, in line with the NyquistShannon sampling theorem.Objective. The current study tested whether humans indeed sample the dials based on bandwidth alone or whether they also use salient peripheral cues.Methods. A dial-monitoring task was performed by 33 participants. In half of the trials, a gaze-contingent window was used that blocked peripheral vision.Results. The results showed that, without peripheral vision, humans do not distribute their attention across the dials effectively. The results further suggest that, in the full-view condition, humans detect the speed of the dial through peripheral vision.Conclusion. It is concluded that salience, rather than expectancies based on learned signal bandwidth, is the prime driver of distributed visual attention in the current dial-monitoring task.Application. The present findings indicate that salience plays a major role in guiding human attention. A subsequent recommendation for future human-machine interface design is that task-critical elements should be made salient.