Age differences in feature and conjunction search: Implications for theories of visual search and generalized slowing

Reaction times (RTs), saccadic eye movements, and fixation durations were measured while older and younger observers searched visual displays for targets defined by a single feature, luminance contrast or orientation, as well as the conjunction of these two features. Target eccentricity was varied between approximately 4 and 14 deg. Age deficits generally increased in the more difficult conditions. the RT data indicated that age deficits were greatest for conjunction search and on target absent trials. the saccade data showed that on target present trials, age deficits were larger for more eccentric targets, especially in conjunction search. Fixation durations were related by a power function to the number of saccades made prior to a correct response. Whereas the exponent of these power functions was constnat across search condition and age group, the coefficient was larger for older adults. Thus at a fixed number of saccades, when old and young were presumably searching groups of equal size, the...