Selective Age Effects on Visual Attention and Motor Attention during a Cued Saccade Task

Abstract

Objective. Visual information is often used to guide purposeful movement. However, older adults have impaired responses to visual information, leading to increased risk for injuries and potential loss of independence. We evaluated distinct visual and motor attention contributions to a cued saccade task to determine the extent to which aging selectively affects these processes. Methods. Nineteen healthy young (18-28 years) and 20 older (60-90 years) participants performed a cued saccade task under two conditions. We challenged motor attention by changing the number of possible saccade targets (1 or 6). Results. Older adults had difficulty in inhibiting unwanted eye movements and had greater eye movement inaccuracy in the hard condition when compared to the younger adults and to the easy condition. Also, an inverse relation existed between performance on the visual and motor components of the task in older adults, unlike younger adults. Conclusions. Older adults demonstrated difficulty in both inhibiting irrelevant saccade targets and selecting correct saccade endpoints during more complex tasks. The shift in relations among attention measures between the younger and older participants may indicate a need to prioritize attentional resources with age. These changes may impact an older adult's ability to function in complex environments.

Figure 1

Stimulus and task. (a) The stimulus as seen by the participant. The central letter (“C” in this figure) changed every 250 ms. (b) An example of stimulus-response mapping for the easy condition. In this case, the participant would perform a saccade to the middle left location whenever any of the 6 target letters were shown. The mapping was not present during the data collection and the mapping changed for every set of 12 trials. (c) An example of stimulus-response mapping for the hard condition in which each cue letter was mapped to a unique peripheral target. (d) An example of a participant making a target selection error. The participant initially selected an incorrect target (top right) and then made a correction to the correct bottom right location. In this case the participant correctly identified the cue letter (“Z”) and recalled the correct mapping (bottom right) but chose an initially incorrect target. (e) A correct trial illustrating saccadic eye movement. In this case, the participant made an initial saccade in the correct direction and then further corrected to the target location prior to returning gaze to the central letter stream. During this trial, the participant overshot in the horizontal direction and undershot in the vertical direction during the initial saccade.

Figure 2

Effects of task condition and age on performance. (a) Both younger and older participants made more target selection errors in the hard condition compared to the easy condition. The older participants also made more target selection errors than their younger counterparts. (b) Mean magnitude of the saccade endpoint accuracy error relative to the target location. (c) Reaction time. Both main effects of condition and age were significantly different with no significant interaction present. (d) Older participants made significantly more visual perception errors (misses and false positives) than the younger participants in both conditions (represented along x-axis). All data are presented as mean ± SEM.