R We Fooling Ourselves: Does the Occlusion Technique Shortchange R Estimates?

The occlusion technique was originally used to evaluate the cognitive demands of the roadway. Recently, the occlusion technique has been used as a cost-effective tool for assessing the visual demand of in-vehicle devices. Occlusions simulate glances from an in-vehicle device to the roadway by interrupting visual sampling. However, occluding the in-vehicle device does not impose any additional cognitive demand on the participant like true glances back to the roadway. The purpose of this study was to compare standard no-task occlusions with occlusions requiring participants to perform a visual-motor tracking task. Results suggest that overestimates of resumability may result by not including a task during occlusions. Furthermore, estimations of visual demand based on individual post-occlusion resumption times may provide a more precise measure of transition costs and resumability than measures based on Total Shutter Open Time.