Automatic-effortful processing and cognitive inertia in persons with mental retardation.

A modified Stroop Color-Word Interference Test (Stroop, 1935) was used to assess automatic-effortful processing in persons with mental retardation and college students in three experiments. In Experiment 1, retarded persons experienced greater Stroop interference than did college students. This was attributed to a failure of control (effortful) processing needed to suppress the automatic reading responses of retarded subjects. In Experiments 2 and 3, all subjects practiced the Stroop color-naming task over three or four daily sessions. Changes in Stroop interference over practice were viewed as reflecting automatization of the suppression of the reading response. Both groups automatized the suppression response at about the same rate, but the automatized responses had far greater and more durable suppression effects for retarded subjects. This persistence of automatized responses, which were no longer adaptive, was described as cognitive inertia, a phenomenon similar to cognitive rigidity as defined by Kounin (1948).