One hundred and thirty-one adults belonging to four age groups (19-26, 50-59, 60-69 and 70-82 years) performed a spatial stimulus-response consistency task in which the response dimension (left or right) overlapped relevant and irrelevant stimulus dimensions. The influence of the irrelevant stimulus dimension on response time was significantly greater in the middle age groups than among 19-26 year-olds, and significantly greater in the highest age group than in any other. This pattern persisted when allowance was made for a significant age-related increase in processing time (measured as reaction time in a single-stimulus, single-response task). It is concluded that in tasks of the kind used, the elderly resist interference from the irrelevant information less easily than do younger persons. Interestingly, comparison of Vincentized quintiles suggested that the effect of the irrelevant stimulus dimension decreased with increasing response time among 19-26 year-olds, but increased with response time among 70-82 year-olds.