Learning-forgetting independence, unidimensional memory models, and feature models: Comment on Bogartz (1990)

Geoffrey R. Loftus, Donald Bamber
1990 Journal of Experimental Psychology. Learning, Memory and Cognition  
In his recent articles, Bogartz offered a definition of what it means for forgetting rate to be independent of degree of original learning. He showed that, given this definition, independence is confirmed by extant data. Bogartz also criticized Loftus's (1985b) proposed method for testing independence. In this commentary, we counter Bogartz's criticisms and then offer two observations. First, we show that Loftus's horizontal-parallelism test distinguishes between two interesting classes of
more » ... y models: unidimensional models wherein the memory system's state can be specified by a single number and multidimensional models wherein at least two numbers are required to specify the memory system's state. Independence by Loftus's definition is implied by a unidimensional model. Bogartz's definition, in contrast, is consistent with either model. Second, to better understand the constraints on memory mechanisms dictated by the mathematics of the models under consideration, we develop a simple but general feature model of learning and forgetting. We demonstrate what constraints must be placed on this model to make learning and forgetting rate independent by Loftus's and by Bogartz's definitions. Is forgetting rate independent of degree of original learning? There has been an ongoing debate, not merely over the answer to this question, but more fundamentally over the method that should be used to answer the question. Slamecka and McElree (1983; see also, Slamecka, 1985) proposed a method for answering this question. Loftus (1985a Loftus ( , 1985b criticized Slamecka and McElree's method and proposed a method of his own. Now, Bogartz (1990) criticized Loftus's method and proposed a method of his own. This article is designed to provide perspective on the entire set of issues and to defend Loftus's (1985b) method against Bogartz's criticisms. Methods for Testing Independence There are three steps--one optional and two mandatory-in devising a method to answer the question "Is forgetting rate independent of degree of original learning?" The first, optional step is to construct a memory mechanism embodying one's intuitive notion of learning-forgetting independence. The second step is to formulate a pattern to which empirical data must conform when there is learning-forgetting independence. (If the optional first step has been implemented,
doi:10.1037/0278-7393.16.5.916 pmid:2147446 fatcat:3qti6lm36zdxlhlpswbc75bkfq