Prolonged disengagement from attentional capture in normal aging

Abstract

Older adults are more vulnerable to a negative impact of irrelevant information on cognitive performance. We used a psychophysical approach to evaluate which aspects of distraction are altered in aging: susceptibility for attention to be captured by a distractor, or the timing of disengagement from processing a distractor. We found that younger and older adults were equally susceptible to a detrimental influence of attentional capture on target detection in the initial moments after distractor presentation, but older adults exhibited a longer time window for the negative effects of capture to resolve. As was recently shown in younger adults, the timing of disengagement from capture correlated with individual differences in visual working memory capacity in the older cohort. These results suggest that the larger impact by distraction on perceptual abilities in normal aging is not the result of a greater susceptibility to attentional capture by distraction, but rather the prolonged processing of distractors.

Figures

Figure 1

Capture task and accuracy for Older and Younger participants. (A) Participants were instructed to identify the orientation of a target Landolt “C” presented in red among an array of three other distractor Landolt “C”s drawn in different colors. On flanker-present trials, there were four possible stimulus onset asynchronies (SOAs) between the flanker and the search array: 50ms, 150ms, 250ms, or 350ms. The flanker appeared either in the same red color as the target stimulus of the subsequent search array (relevant flanker) or in a distractor color of blue (irrelevant flanker). (B) Younger participants' accuracy in the relevant flanker condition (‘Rel F’ – in red) steadily increased with longer SOAs between flanker and target stimuli until plateauing at 250ms. This effect of SOA on accuracy was not observed for the no flanker (‘No F’ – in blue) or irrelevant flanker condition (‘Irrel F’ – in green). (C) Older participants displayed no increase in accuracy for any of the conditions across SOAs.

Figure 2

Capture cost in Older and Younger adults. Using an index of capture cost for relevant capture (solid lines) and irrelevant capture (dotted lines), both older adults (black lines) and younger adults (grey lines) are equally captured by relevant distracters at the shortest SOA of 50ms. However, older adults exhibited a prolonged capture cost for relevant distracters differentiating the age groups at 250ms (* p = 0.0001). No group differences were found at any SOA for irrelevant capture costs (all p>0.05).

Figure 3

Relevant capture cost and VWMC age groups. Older participants were divided into high VWMC (grey dotted line) and low VWMC (black solid line) subgroups by use of a median split. This resulted in a subgroup of older participants with significantly lower VWMC than younger participants (grey solid line), as well as, a subgroup of high VWMC older participants that was comparable in VWMC to younger participants (B). No differences for relevant capture between any of the groups were found at the shortest SOA of 50ms (A). The older high-VWMC exhibited an increased capture cost at 250ms (* p=0.013), however by 350ms there was no significant difference between the older high-VWMC subgroup and younger adults. While the older low-VWMC subgroup displayed greater relevant capture costs at all subsequent SOAs compared to younger adults, and deviated from the older high-VWMC subgroup at 350ms (**p = 0.001). The older high-VWMC subgroup was tested on a subsequent version of the capture task with an extended range of SOAs (black dotted line) where it was shown that this group's relevant capture cost returns to that of the other groups by 550ms. (C) Individual relevant capture cost performance at SOA of 350ms correlated with individual K estimates of VWMC in older adults.