Changes (but not differences) in motion direction fail to capture attention

Attentional Tunneling in Pilots During a Visual Tracking Task With a Head Mounted Display

OBJECTIVE

We examined whether active head aiming with a Helmet Mounted Display (HMD) can draw the pilot's attention away from a primary flight task. Furthermore, we examined whether visual clutter increases this effect.

BACKGROUND

Head up display symbology can result in attentional tunneling, and clutter makes it difficult to identify objects.

METHOD

Eighteen military pilots had to simultaneously perform an attitude control task while flying in clouds and a head aiming task in a fixed-base flight simulator. The former consisted of manual compensation for roll disturbances of the aircraft, while the latter consisted of keeping a moving visual target inside a small or large head-referenced circle. A "no head aiming" condition served as a baseline. Furthermore, all conditions were performed with or without visual clutter.

RESULTS

Head aiming led to deterioration of the attitude control task performance and an increase of the amount of roll-reversal errors (RREs). This was even the case when head aiming required minimal effort. Head aiming accuracy was significantly lower when the roll disturbances in the attitude control task were large compared to when they were small. Visual clutter had no effect on both tasks.

CONCLUSION

We suggest that active head aiming of HMD symbology can cause attentional tunneling, as expressed by an increased number of RREs and less accuracy on a simultaneously performed attitude control task.

APPLICATION

This study improves our understanding in the perceptual and cognitive effects of (military) HMDs, and has implications for operational use and possibly (re)design of HMDs.

Pop-out for illusory rather than veridical trajectories with double-drift stimuli

If a patch of texture drifts in one direction while its internal texture drifts in the orthogonal direction, the perceived direction of this double-drift stimulus (also known as the infinite regress and curveball illusions) deviates strongly from its physical direction. Here, we use double-drift stimuli to construct two types of search arrays: The first had an oddball target in terms of the physical trajectories, but no oddball for the perceived trajectory, whereas the second had a perceptual oddball, but no physical oddball. We used these two arrays to determine whether pop-out operates over physical or perceived trajectories. Participants reported the location of the odd double-drift stimulus that had either a unique physical or perceived trajectory in a set of four or eight items. When the distractors all shared one perceived trajectory, but the target had an odd perceived trajectory, it popped out even though the physical trajectories of the stimuli were mixed: Accuracy rates were at ceiling, and response times decreased with increasing set size. In contrast, participants were significantly less accurate and slower at finding the physical oddball when all the paths had a common perceived trajectory. Moreover, responses became less accurate and slower with increasing set size. Our findings suggest that, at least for this type of stimulus, perceptual features can be processed rapidly, whereas the search for physical features is very inefficient.