The effects of age on guided conjunction search.

The effect of age on top-down guidance in visual search for conjunctions of form and motion was examined with a task developed by Driver et al. (1992). Young (mean age = 19.2 years) and old (mean age = 77.3 years) adults searched for a vertically oscillating X among varying numbers of vertically oscillating Os and horizontally oscillating Xs. The ease with which subjects could use top-down guidance to improve search efficiency was manipulated by varying the motion coherence of display items. Overall, older adults produced steeper response-time-display-size slopes than did young adults, and both age groups showed significant reductions in slopes when distractors oscillated coherently. Older adults, however, produced proportionally smaller reductions in slope than did younger adults, suggesting that age affects the efficiency of top-down guidance in conjunction search for form and motion.