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.
Prospective workload measures are used to assess individuals' expectations about tasks they are facing, how difficult they think the tasks will be and how well they expect to perform. In this study, 43 participants used the NASA-TLX subjective workload scale to predict the difficulty of surgical training tasks. The goal of the study was to determine the accuracy of their predictions and whether the act of assessing tasks before performing them affected their judgments post-performance. Regarding initial performance, results showed that participants formed prospective judgments that were consistent with their retrospective judgments, but they underestimated physical demands. After only minimal practice, however, their retrospective judgments deviated from both the experimental group's initial predictions and the control group's initial retrospective assessments. Anticipating mental demand was particularly challenging. No significant differences were found between the control and experimental conditions for post-performance assessments, suggesting that pre-performance assessment of workload has no effect of post-performance judgment of task difficulty.
As shopping from online retailers continues to increase, designers need to be aware of the strategies consumers are using to predict the ease-of-use of products based on appearance. The following study investigates the influence of task type (stimulus-response compatibility task, target-acquisition task, perceptual-search task) on these strategies. The results suggest that for abstract tasks (motor and search), participants are relying on elements in or interactions with the actual stimulus such as the predicted time to complete the task and the number of items in the stimulus. However for tasks that are more concrete (using a stove), participants rely on their past experiences and familiarity with the task to predict task difficulty.
The availability of adjustable lighting controls, with options other than “on” and “off,” have been associated with increased energy savings. In the present study, we describe the way customizable, networked lighting controls are actually used in a recently built research facility that received a formal designation for sustainable design (LEED Gold). In addition to usage patterns, we explored occupants’ knowledge of control operation as well as the expectancies of nonoccupants. We also identified a variety of features that, if redesigned in accordance with HF/E principles, might lead to reduced lighting usage.
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