Performance consistency in picture naming: a study of the rehabilitation effect on two patients

We describe the effect of language rehabilitation on the naming deficits of 2 patients affected by longstanding amnestic aphasia. In particular, our aim was to study the evolution of the rate of inconsistent naming (i.e., performance with stimuli that were named sometimes correctly and sometimes incorrectly when the test was repeated at close intervals) by means of a stochastic model based on Markov chains (Faglioni and Botti, 1993). From a quantitative point of view, both patients showed a significant improvement that was still present several months after treatment. However, at baseline these patients showed different degrees of consistency which revealed a basic difference in the way their language functions. One case presented with low consistency, delayed responses, and self-corrections: A clear effect of rehabilitation was improvement in consistency and reduction of delays. In the other case, at baseline consistency was greater, but naming of pictures did not improve even after delay or self-correction; after rehabilitation more stimuli were named correctly, but only after delay and self-correction. The relevance of consistency and its relationship with delayed naming and self-corrections is discussed. It is suggested that consistency analysis based on stochastic models would make a useful contribution to the description and interpretation of naming deficits in aphasic patients.