Inferring Psychological Dissociations from Experimental Dissociations: The Temporal Context of Episodic Memory
David S. Olton
The Johns Hopkins University
In my conversations with Endel Tulving, I have always come away wiser and more knowledgeable: wiser because I have learned something about the logic of analysis; more knowledgeable because I have learned some more information about the organization of memory. This chapter reflects both of his contributions.
The first part concerns the classification problem in learning and memory ( Tulving, 1985) and asks the question, "How many memory systems are there?" ( Tulving, 1985b). It discusses the types of empirical dissociations that are necessary to make strong inferences ( Platt, 1964) about functional dissociations of psychological processes and neural mechanisms, and suggests that our experimental designs are not yet sufficient to demonstrate qualitative, all-or-none distinctions that separate memory into two different categories (see also chapters 1, 6, and 13, this volume). More broadly, these data suggest that a dimensional view of memory is preferable to a dichotomous one.
The second part concerns the elements of episodic memory ( Tulving, 1983), particularly the neural systems that are involved in temporal discriminations. It focuses on the frontal cortex and the hippocampus, both of which have been implicated in temporal processes associated with memory ( Milner, Petrides, & Smith, 1985; Rawlins, 1985), and shows that these subserve complementary functions in temporal discriminations.
Dissociations to the memory researcher are what fruit flies are to the geneticist: a convenient medium through which the phenomena and processes of interest can be explored and elucidated (adapted from Tulving, 1983, p. 146). As emphasized by Fodor ( 1985), the Handsome Cognitivist has been seeking dissociations