Objective: To use Sternberg’s Additive Factor Method to determine whether patients with mild Alzheimer disease (AD) are slow in information processing and/or response execution.
Methods: We gave an odd-even categorization task to 16 patients with probable mild AD and 17 age-matched healthy controls. We recorded reaction and movement times to stimuli varying for noise, target set size, stimulus-response compatibility, and fore-period interval, to probe the cognitive and motor stages of information processing.
Results: Both groups performed the task accurately, indicating good preservation of odd-even categorization in mild AD. The AD group’s reaction times were similar to the controls’ across conditions, and not selectively affected in any of the cognitive stages of the Additive Factor Method. However, the AD group’s movement times were slower than the controls’ across conditions.
Conclusions: AD patients’ performance on a task requiring categorization ability was slowed more by motor than cognitive components of information processing. When evaluating the performance of patients with AD in reaction-time paradigms, we should not attribute group differences solely to differences in cognitive processing. Execution components should also be considered.
*Neuropsychology Unit, Istituto Di Ricovero e Cura a Carattere Scientifico Fondazione Santa Lucia, Rome, Italy
†Department of Psychology, Sapienza University of Rome, Rome, Italy
‡Memory Clinic, Centre for the Medicine of Aging, Catholic University, Rome, Italy
Supported by a grant from the Italian Department of Health to the Istituto Di Ricovero e Cura a Carattere Scientifico Fondazione Santa Lucia and a PRIN (Ricerche di Rilevante Interesse Nazionale) 2005 grant from the Italian Department of Education, University and Research (Ministero dell’Istruzione, dell’Università e della Ricerca) to M.C.S.
P.Z. is a member of the Marie Curie Research and Training Network: Language and Brain (RTN-lab), funded by the European Commission (MRTN-CT-2004-512141) as part of its Sixth Framework Programme.
The authors declare no conflicts of interest.
Reprints: Marialuisa Martelli, PhD, Department of Psychology, Sapienza University of Rome, Via dei Marsi 78–00185 Roma, Italy (e-mail: email@example.com).
Received March 3, 2010
Accepted July 17, 2012