Reliance on central vs. peripheral vision for visual search in younger and older adults

International audienceIt has been suggested that older adults rely more on their central vision at the expense of peripheral vision, compared to younger adults. To test this, we examined how older and younger participants performed two visual search tasks: pop-out and serial, in the presence of artificial central scotomata. Pop-out search relies on processing of the entire visual scene (i.e. global processing) whereas serial search requires processing of each feature serially (i.e. local processing). 13 healthy younger (M = 21.8, SD = 1.5) and 15 older adults (M = 69.1 years, SD = 7.3) performed a pop-out and a serial version of a visual search task in the presence of different sized gaze-contingent artificial central scotomata (no scotoma, 3° diameter, 5° and 7°). Participants were asked to indicate as quickly as possible whether a target was present or not among distractors whose number varied (16, 32 or 64 objects). We found evidence for a greater decline in peripheral processing in older adults compared to younger in pop-out but not in serial search. For the pop-out condition with no scotoma, we found that the further the target in the periphery, the longer the search time, and that this increase was proportionally greater for older adults compared to younger adults. Further, increases in scotoma size were associated with a greater increase in reaction times for older adults compared to younger participants. For the serial condition, both groups showed similar increases in reaction times with target distance from center and scotoma size. We surmise that this may be due to task difficulty in serial search; central vision is necessary for both groups. In conclusion, these findings suggest that, in global processing, older adults distribute more resources towards central vision compared to younger adults