Expectancy or Salience?—Replicating Senders’ Dial-Monitoring Experiments With a Gaze-Contingent Window

Introduction
In the 1950s and 1960s, John Senders carried out a number of influential experiments on the monitoring of multidegree-of-freedom systems. In these experiments, participants were tasked with detecting events (threshold crossings) for multiple dials, each presenting a signal with different bandwidth. Senders’ analyses showed a nearly linear 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 Nyquist–Shannon 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 effectively distribute their attention across the dials. The findings also suggest that, when given full view, humans can detect the speed of the dial using their peripheral vision.

Conclusion
It is concluded that salience and bandwidth are both drivers of distributed visual attention in a 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.