Assessing the role of attention, eye-movements and expectations of icon appearance vs. icon position.
Here we assess the impact of icon appearance vs. icon position based on user familiarity with Mac vs. Windows OS. In addition to learning which of these icon features drives search performance, we also investigate the role of attention using 2 approaches:
1) Assessing the inhibitory nature of attention using the probe-dot technique described in our initial study, &
2) Assessing whether whether attention, or where you look, accounts for search performance.
What is the role of attention & eye-movements? Do these align?
It is useful to distinguish Overt vs. Covert forms of attention to assess whether attention, or where you look, accounts for search behavior:
Overt attention occurs when we look at targets that we successfully detect & find. This is revealed when fixations & mouse click behaviors agree.
Covert attention occurs when participants accurately detect both the target (and the probe-dot) but do not necessarily have their gaze on either.
Methods for assessing attention, eye-movements & usability
40 students participated in 2 Blocks of 90 trials
Eye-movements were recorded using Eyelink 1000 eye-tracker.
Tasks
Participants performed search & probe-dot detection tasks on computer simulations of Mac vs. Windows OS. We compared Icon-position & icon-appearance, and whether they differed from standard OS design.
Survey questions following experimental conditions explore whether performance measures map on to users’ impression of task difficulty and whether they noticed unexpected changes to the display.
Familiarity of Icon appearance (Icon-ID) & Icon- Position: We query participants about their familiarity with Mac vs. Windows OS. This allows us to compare search for familiar/expected vs. unfamiliar/unexpected icons and screen locations.
Self-reported usability was assessed with a survey at the end of the experiment where we asked about ease of finding information & whether users noticed any changes across conditions.
Findings
Familiarity of icon position has a much greater impact than icon identity on finding targeted information:
Search is faster, with shorter fixations when icons are in a familiar, expected position (where there was no change in icon location) than when items are in an unfamiliar, unexpected location (that had changed from the default location). First click accuracy showed no significant difference across changed vs. no change conditions.
Search Times: When icon position changes (red bars) from default OS position, search is slower, than the no-change (familiar & thus, expected) default positions (blue bars). Changes to icon appearance (i.e., icon ID) has no effect on search times.
Gaze/Fixation Duration: When icon position changes (red), fixation duration is shorter than when there is no change in position (blue). So we spend less time looking at icons that have changed position than those that were unchanged. Changing icon-ID has no significant effect on gaze duration.
Summary of search & usability findings:
Surveys, & usability-testing show a significant correlation between perceived and actual ease of finding targeted information, with participants taking longer to find the target, and looking less at the targets when there were unexpected changes to icon position. Participants also reported that they did notice when an icon was in an unexpected position, but they often did not notice changes to the icons’ id.
Conclusions
Familiarity with icon position drives search performance-- participants look for the icon where they expect it to be. When target icons are in an unexpected position, participants’ search slows down.
Expected position of a target icon tends to drive fixations and users’ attention, whereas the expected icon’s appearance does not.
Alummoottil, D., Livingston, K., Caputo, P. Homare, K., & [Advisor:] Aks, D.J. (2015 & 2016) Evaluating Effectiveness of O.S. Design with Eye-Tracking and Inhibition Testing. Rutgers University Undergraduate Symposiums
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