Categorical Imperatives: Implicit Learning and Alzheimer's Disease

Categorical Imperatives
Reported by
Alisa G. Woods

Posted March 22, 2006

Presented By


Grouping related items together based on their similarity seems so obvious and intuitive that many of us may not ever have considered how we accomplish this task. Mental processes underlying categorization are a bit more complicated than they may appear, though, and have been studied for decades by psychologists, and more recently by neurobiologists. Their research is revealing that different strategies may be used to form categories, and that we may not even be aware that we are using a strategy or forming a memory. This process is known as implicit learning.

To understand how categories are formed, however, it is first necessary to define what a category is. In a meeting of the Academy's Psychology Section on December 5, 2005, Edward Smith of Columbia University discussed what categories are and how category learning takes place.

Journal Articles

Bozoki, A. & E. E. Smith. 2006. Can patients with Alzheimer's disease learn a category implicitly? Neuropsychologia 44: 816-827

Knowlton, B. J. & L. R. Squire. 1993. The learning of categories: parallel brain systems for item memory and category knowledge. Science 262: 1747-1749.

Palmeri, T. J., & M. A. Flanery. 1999. Learning about categories in theabsence of training: profound amnesia and the relationship between perceptualcategorization and recognition memory. Psychol. Sci. 10: 526-530. Full Text (PDF, 51 kB)

Reber, P. J., D. R. Gitelman, T. B. Parrish & M. M. Mesulam. 2003. Dissociating explicit and implicit category knowledge with fMRI. J. Cogn. Neurosci. 15: 574-583.

Reed, J. M., L. R. Squire, A. L. Patalano, et al. 1999. Learning about categories that are defined by object-like stimuli despite impaired declarative memory. Behav. Neurosci. 113: 411-419.


Edward E. Smith, PhD

Columbia University
email | web site | publications

Edward Smith is the William B. Ransford Professor of Psychology at Columbia University. Prior to his move to Columbia, he was the Arthur W. Melton Professor of Psychology at the University of Michigan, where he served as director of the cognitive science and cognitive neuroscience program. Well known for his seminal work in the areas of concepts and categorization and verbal working memory, he is an elected member of the National Academy of Sciences and the American Academy of Arts and Sciences. He has served as chair of the Cognitive Science Society, chair of the Psychonomic Society, editor of Cognitive Science, and reviewing editor of Science. Smith has been awarded the APA Distinguished Scientific Contribution Award and the APS William James Fellow Award for Distinguished Scientific Achievements.

Alisa G. Woods

Alisa G. Woods, PhD, is a neurobiologist, biomedical communications consultant, and Adjunct Professor of Psychology at Iona College.