Age differences in stroop-like interference as a function of semantic relatedness

The disinhibition hypothesis advanced by Hasher and Zacks (1988) predicts a faulty inhibitory mechanism resulting in ''increased breadth of activation of nongoal path ideas'' with aging (p. 213, Fig. 1). To assess this prediction, we tested young and older adults with a modified Stroop paradigm in which the semantic relationship between the words and ink colors was varied. Items were presented in five conditions: Stroop words (BLUE), related color words (NAVY), related words (SKY), neutral words (REFER), and asterisks (***). We found an age difference in interference for the Stroop words only: that is, when the response set was the same as the stimulus set, older adults' color-naming performance was jeopardized. In contrast, young and older adults did not differ in proportional slowing when related colors, related words, neutral words, or asterisks were presented. The findings are discussed in terms of three explanations: (a) a developmental dissociation between response suppression and semantic suppression; (b) weaker semantic activation; and (c) the effect of paradigm differences.