A "White-Space" Effect in Users' Anticipation of the Challenges Involved in Using Everyday Products

Abstract

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.

A First Look at Identifying Strategies People Use in Making Predictions about Task Demand

“…While these prospective judgments of ease-of-use are understandably important, consistently people are unable to accurately predict performance decrements or workload increases influenced by design manipulations (Bailey, Carswell, Grant, & Basham, 2007;Payne, 1995;Smallman & St.John, 2005;Stephens, Carswell, & Schumacher, 2006;Sublette, et al, 2009;Sublette, Carswell, Seidelman, Clarke, & Seales, 2011). Despite users' inabilities to accurately predict task demand or interactions between tasks and tool design, user satisfaction and loyalty may be dependent on the accuracy of these very same decisions.…”

“…(Osborne & Ellingstad, 1987). However when participants tried to anticipate the amount of workload imposed from using these stove designs, they anticipated no difference between the two designs without sensor lines and believed the design with the sensor lines would be the most difficult to use (Sublette, Carswell, & Seidelman, 2012-unpublished;Sublette, et al, 2011).…”

“…The control-burner arrangements stimuli and the Fitts' task stimuli were previously used by Sublette et al (2011). Stove burner-control task.…”

“…The instructions for judging these stimuli, modified slightly from Sublette et al (2011), were as follows:…”

“…In the present study, thirteen possible heuristics that participants might use to predict the workload of specific tasks were chosen based on participants' comments during previous prospective workload experiments (Sublette, et al, 2009;Sublette, et al, 2010;Sublette, et al, 2011). These heuristics were used to generate strategy descriptions that could be endorsed by participants as being representative of the strategies they actually used to complete a series of prospective workload judgments.…”