Abstract
We investigated spatial localization in younger and older adults as a function of target azimuth for visual and auditory stimuli. Thirteen younger subjects (21 to 33 years) and twelve older subjects (59 to 78 years) participated in a localization task. All subjects had normal vision and hearing. Stimuli were 200-millisecond auditory pink noise (0.2kHz- 8kHz) and/or visual white disks (subtending ~3°) presented at 17 locations along the horizontal plane (from 90° left to 90° right). For analyses, locations were collapsed across hemifields and categorized into central (0° to 30°) and peripheral (60° to 90°) space. Subjects verbally estimated azimuth (e.g., “left, 25 degrees”) of targets in four conditions: multimodal (simultaneous visual and auditory cues); visual cue (with no auditory cues); auditory cue (with no visual cues); and auditory while blindfolded (no visual cues and no visual context). We measured accuracy (the unsigned difference between reported and actual target locations) and variability (the standard deviation of responses within each location). In central space, each group localized visual and multimodal cues better than those in either auditory condition; in peripheral space, each group showed comparable performance regardless of condition. Responses were less variable in central space than peripheral space in all four conditions in each group, with one exception: older participants, when wearing blindfolds, had similar performance regardless of target azimuth. Furthermore, performance between groups was statistically different only when localizing central auditory targets while blindfolded, in which case older participants were less precise than younger participants. This suggests that, while localizing auditory targets, older participants rely more on anchoring their responses to their visual environment than do younger participants, a strategy that may be more effective in high-acuity central space. Otherwise, our results reveal largely intact spatial localization in typical aging.
Acknowledgement: NIH grant EY002934, NSF DGE-1734815, University of Minnesota CATSS 5334800-UMF0021212