White Cale, Wheatley Dana, Konwisorz Olga, Scialfa Charles T
Department of Psychology, University of Calgary, Calgary, Alberta, Canada.
Neuropsychol Dev Cogn B Aging Neuropsychol Cogn. 2007 Sep;14(5):487-504. doi: 10.1080/13825580600672155.
Latencies (RT) and eye movement measures were used to examine the effects of age and contrast on the distractor-ratio effect (DRE) in visual search. Younger and older adults performed a contrast x orientation conjunction search task where the ratios of white to black distractors and luminance contrast levels were varied. The distractor-ratio manipulation had similar effects for older and younger adults on both RT and the number of fixations required to find the target. Both measures were largely independent of distractor ratio on target-present trials, while both RTs and the fixation number increased with the number of items sharing the target's contrast polarity on target-absent trials. A more detailed analysis of eye movements suggested that younger adults were a bit more adept at attending to the smaller set of distractors, which presumably facilitated both overt and covert search. Generalized slowing can account for the age differences in RT, but the fixation number data speak to another mechanism, perhaps increased cautiousness on the part of the elderly when signal strength is low.
反应时（RT）和眼动测量被用于检验年龄和对比度对视觉搜索中干扰项比例效应（DRE）的影响。年轻和年长成年人执行了一项对比度×方向联合搜索任务，其中白色与黑色干扰项的比例以及亮度对比度水平有所变化。干扰项比例操作对年长和年轻成年人的反应时以及找到目标所需的注视次数都有类似影响。在目标存在的试验中，这两种测量在很大程度上与干扰项比例无关，而在目标缺失的试验中，反应时和注视次数都随着与目标对比度极性相同的项目数量增加而增加。对眼动的更详细分析表明，年轻成年人在关注较少的干扰项集合方面略胜一筹，这大概有助于显性和隐性搜索。普遍的反应时减慢可以解释年龄在反应时上的差异，但注视次数数据表明存在另一种机制，可能是老年人在信号强度较低时更加谨慎。
