Modeling Cued Recall and Memory Illusions as a Result of Structure Mapping

Modeling Cued Recall and Memory Illusions as a Result of Structure Mapping Georgi Petkov (gpetkov@cogs.nbu.bg) Boicho Kokinov (bkokinov@nbu.bg) Central and East European Center for Cognitive Science Department of Cognitive Science and Psychology New Bulgarian University 21 Montevideo Str. , Sofia 1618, Bulgaria Abstract A model of cued recall is proposed. Its basic assumption is that processes of structural mapping and analogical transfer lie at the core of human cognition. Recall is viewed as a result of construction of a new episode, analogical to the old episode. The response items emerge from dynamic creation and competition of various hypotheses about what has happened. Thus, some psychological data about constructive nature of human memory are explained as resulting from constraints that are natural for the process of analogical mapping. Several simulations tested the model from different aspects. Finally, the role of connectedness of the episodes for the quality of their recall is explored in more details. Keywords: Constructive memory; Analogy-making; Memory illusions; Cognitive modeling. Introduction During the last several decades experimental data have been accumulated in support of the phenomena of false, illusory memories (Bartlett, 1932, Deese, 1959, Loftus 1977, 1979, 2003, Roediger & McDermott, 1995, Schacter, 1995, 1999, Kokinov & Hirst, 2003). Ulrich Neisser (1967) proposed the constructive approach to human memory by analogy with the constructive approach to perception which was based on the phenomena of visual illusions. According to Neisser, recall is an active process of interpreting old memory traces, just as vision is viewed as an active process of interpreting visual information. Thus, recall includes a process of constructing and testing hypotheses about past events on the basis of various constraints and contextual information. The problem is that there are very few computational models that account for illusory memories. The CHARM model (Metcalfe, 1990), the TODAM2 model (Murdock, 1995), and the Complementary Learning Systems (CLS) model (McClelland et al. 1995) are able to simulate the phenomena of blending of two similar episodes. However, all these models use in one way or another feature vector representations and are not sensitive to the structure of the episode. That is why they cannot account for the psychological data on blending of dissimilar episodes (Kokinov & Zareva, 2001) based on their structural similarity with a third episode. Tulving (Tulving, & Watkins, 1973, Tulving, 1982) suggested that recall and recognition are processes of memory construction combining information from the encoded traces and the current environment (cues, questions, etc.). Kintsch (1988) working on text comprehension suggested similarly that information from memory and inferred elements are combined with the input while building the internal representation of the text. Following these traditions we have developed a model that postulates that the specific mechanism for the constructive process of memory is analogy-making (Kokinov, 1998; Kokinov & Petrov, 2001). People usually think of analogy-making (Gentner, 1983, Falkenhainer et al., 1989, Hummel & Holyoak, 1997) as a slow, deliberated process of comparing structures from two domains. However, we assume that the basic mechanisms of analogy-making (such as structural mapping and transfer) may be very fast, unconscious, and parallel. Hofstadter and his colleges (Hofstadter, 1984, 1995, 2001) assume that analogical thinking lies at the core of human cognition and proposed several models of high-level vision, based on analogy-making. The DUAL architecture (Kokinov, 1994a) and the AMBR model (Kokinov, 1994b, Kokinov & Petrov, 2001) propose fast, parallel mechanisms of retrieval and mapping. Thus, analogy-making seems a promising basis for modeling various cognitive processes. The current model of memory recall is based on the DUAL architecture, inherits its mechanisms and provides few new ones, and is integrated with the other DUAL-based models like the AMBR model for high-level analogy making (Kokinov, & Petrov, 2001), the JUDGEMAP model for judgment on a scale (Petkov, 2006), and the RecMap model for visual recognition (Petkov, Shahbazyan, 2007). This paper describes an attempt to further extend a model of memory that was capable of question answering and which simulated and predicted the dissimilar episode blending phenomenon (Grinberg & Kokinov, 2003). The problem with this model was that it required a detailed structural description of a specific question (e.g. “Where did the coffee cup break down”) and thus could not be used directly in simulation of a typical memory task such as “Please, recall the elements of the list of words that you studied two days ago in the lab”. This more general type of recall is less structured and we do not know in advance how many and what kind of elements we are looking for. We are trying to overcome this limitation in the current paper. We first briefly describe the mechanisms of the model and the results of several simulations and then compare them with psychological data obtained earlier (Kokinov, Petkov, Petrova, 2007).