Do more pictures mean more effort? Investigating the effects of monocular depth on target detection in a 3D WIMP pictures folder

The limited commercial success of 3D WIMP interfaces, despite ongoing efforts, leads us to question whether depth itself is detrimental to task performance due to, e.g., an increase in the amount of clutter, or if the lack of any success can be mostly attributed to unsuitable interactivity with input devices made for 2D interfaces. In this study, we evaluate a common interactive task -browsing a pictures folder- and argue that despite an increase in the number of nontarget distractors available on the screen when introducing monocular depth, there is no decrease in target detection times, nor are there any changes in cognitive load (as measured through pupillometric data). Interestingly, eye tracking data indicates that this is not due to a lack of fixations, as participants tend to spend proportionally less time fixating on pictures in front of them as more items become available in the background. Finally, our participants made significantly more target identification errors when there were only two picture-layers of visible depth, when compared to four picture-layers. We therefore suggest adding monocular depth cues to 3D WIMP photo gallery or desktop pictures folder applications.