A "white-Space" effect in users' anticipation of the challenges involved in using everyday products

Although the use of prospective workload judgments (i.e., judgments obtained from users prior to any actual interaction with a product) may be appealing for a variety of logistical reasons, a growing literature highlights the biases and metacognitive misconceptions that sometimes lead such judgments to be far from what is found in post-performance evaluations. The current study uses the NASA Task Load Index (NASA-TLX) in a prospective workload judgment task that employs two familiar stimulus sets from the human factors literature as to-be-rated designs: 1) control-burner arrangements on cooktops, and 2) control layouts for pointing tasks that vary in terms of Fitts' Law parameters. Participants made reliable errors (compared to known performance outcomes) when judging both stimulus sets. In general, lower workload judgments were associated with designs that had greater intervening white space between controls and displays/targets.