Further evidence for cognitive inertia of persons with mental retardation.

Two experiments confirmed and extended earlier research (Ellis, Woodley-Zanthos, Dulaney, & Palmer, 1989) showing that persons with mental retardation are more rigid than persons without mental retardation. In Experiment 1 subjects read Stroop words, practiced naming the colors of Stroop words, and then read the Stroop words again. Postpractice reading interference was related to amount of practice, and the interference effect was much greater in persons with mental retardation. We hypothesized that the practice led to automatization of a reading suppression response that had greater cognitive inertia for persons with mental retardation and, therefore, had a greater effect on postpractice reading for them. This cognitive inertia effect was shown to be quite durable in persons with mental retardation, lasting more than 3 months for 10 of 13 subjects. The effect disappeared within a month for persons without mental retardation.