Eye and Head Movements in the Acquisition of Visual Information

Abstract

Much of the literature dealing with the measurement of eye movements is restricted to data collected under conditions where the head is "stabilized". Since in the "real world" such restrictions cannot readily be imposed on operators, we here review the literature dealing with the use of head movements in the acquisition and processing of visually presented information. Task difficulty is associated with an increase in the likelihood of using head movements to acquire visually presented information. Such head movements have been described with visual information subtending as little as 5-10 degrees of arc. The present study, requiring subjects to identify and process information presented at 10 degree eccentricity, determined that such head movements do occur. Head movements were not measured directly but inferred from differences in eye movement amplitude as measured with electrooculography, and gaze shift measured with video camera technology. We raise the issue of generalizability of results obtained under conditions where the head is "stabilized" to conditions where it is free to move.

Operational implications of varying ambient light levels and time‐of‐day effects on saccadic velocity and pupillary light reflex

“…Volunteers may have experienced anticipation in the first test (resulting in sympathetic‐induced pupil dilation) but less so in the second and third tests, (resulting in increased relative parasympathetic constriction). This is supported by the findings of Stern et al. (2005) and Fukuda et al.…”

“…Volunteers may have experienced anticipation in the first test (resulting in sympathetic-induced pupil dilation) but less so in the second and third tests, (resulting in increased relative parasympathetic constric-tion). This is supported by the findings of Stern et al (2005) and Fukuda et al (2005) who reported an increase in IPD during stimulus anticipation and Pfeifer et al (1982) who reported that an increase of activity of the sympathetic system and inhibition of activity of the parasympathetic system may prolong CL. In our experiment, after the first test, the activity of the sympathetic nervous system may have decreased and the activity of the parasympathetic system increased, providing the basis for the decrease in CL in the post-5min tests.…”

Eye-Blink Behaviors in 71 Species of Primates

“…If primates increased monitoring activity, the blink rate would have decreased to maintain a higher vigilance level as the group size increased. Human pilots in flight simulators were shown to blink more frequently and with longer durations when flying over “friendly” (less vigilant) skies than when flying over “enemy” territory [65]. Furthermore, when they were targeted by enemy radar, the pilots blinked very infrequently and the blinks were of very short duration [65].…”

“…Human pilots in flight simulators were shown to blink more frequently and with longer durations when flying over “friendly” (less vigilant) skies than when flying over “enemy” territory [65]. Furthermore, when they were targeted by enemy radar, the pilots blinked very infrequently and the blinks were of very short duration [65]. Under some specific vigilant contexts, eye-blink rates actually decreased in humans.…”

Right–Left Asymmetries in the Whisking Behavior of Rats Anticipate Head Movements

“…For example, the amplitude of head movements during a gaze shift depends strongly on the initial alignment of the eyes (Volle and Guitton, 1993), but can also depend on task difficulty and on the individual (Stern et al, 2005). In addition, the extent of VOR suppression is also highly individualistic .…”