Testing for Spatial Relational Symmetry in Rats’ "Cognitive" Maps

(Paper accepted for presentation April 10, 1998 at the Southern Society for Philosophy and Psychology Conference in New Orleans)

Christopher G. Prince and Adam P. Flettrich

Authors’ Notes: C. G. Prince is with the Center for Advanced Computer Studies, University of Southwestern Louisiana. A. P. Flettrich is with the Department of Psychology, University of Southwestern Louisiana. Correspondence should be addressed to C. G. Prince, New Iberia Research Center, University of Southwestern Louisiana, 4401 W. Admiral Doyle Dr., New Iberia, LA 70560. Email: cgp@cacs.usl.edu

Various animal species have generally not done well on object-oriented psychological tests for relational symmetry (e.g., Schusterman & Kastak, 1993; Sidman, Rauzin, Lazar, Cunningham, & Carrigan, 1982; see Horne & Lowe, 1996 for a review). Animals however, may not exhibit their best abilities in object-oriented domains. For example, animals such as rats appear to have strong cognitive abilities, including some with relations, in the spatial domain (e.g., Macuda & Roberts, 1995; Morris, 1981; Olton & Samuelson, 1976). In this research we address the question: Does the spatial domain provide rats with an advantage on tests of relational symmetry?

A number of authors specify a theoretical connection between relational symmetry and cognitive capacities in general. Fodor and Pylyshyn (1988), for example, include relational symmetry in their characterization of classically cognitive abilities. They expect any system (human, animal, or machine) that is typified as classically cognitive to be able to know systematically related propositions given knowledge of an initial proposition. For example, if the individual knows John loves Mary then that individual can also know Mary loves John. In our research with rats we consider a relational property of "emergent symmetry" (Sidman & Tailby, 1982). Emergent symmetry occurs when an individual knows Mary is related to John without additional learning experiences after initially learning that John is related to Mary (for example). We take the phenomena of emergent symmetry to be directly related to relational symmetry properties. Emergent symmetry is the case where the relation learned is symmetrical and thus knowledge of aRb (e.g., John is related to Mary) entails at least tacit knowledge of bRa (e.g., Mary is related to John).

We take the approach of looking for emergent symmetry in nonhuman animals because it seems related to human propositional knowledge and human relational symmetry. With positive results on emergent symmetry in nonhuman animals it will be necessary to assess whether or not what the animals are doing bears detailed resemblance to human propositional knowledge. To test rats for spatial emergent symmetry we are training them on pairs of conditional relations between locations. Given four locations designated as X1, Y1, X2, and Y2, the rats are trained:

After this training, the rats are examined for their choice of a second location after first finding food at locations Y1 or Y2:

If rats have spatial emergent symmetry capacity they should proceed directly from Y locations to X locations after learning if-X-then-Y. Without emergent symmetry, the animals should display an acquisition rate on the backward trial types similar to the initial forward relation learning rate.

Two experiments, numbered 1 and 2, have been conducted with two separate groups of 12 male rats, using four arms of a radial maze as location stimuli. Rats were first trained on forward if-then relations between locations, and then tested on the corresponding backward relations. Results indicate rats can learn the forward if-then relations rapidly ¾ 11 of the 12 rats in Experiment 2 learned the forward conditional relations to better than 88% correct in an average of 90 trials. Testing has shown no signs of emergent symmetry. We are now conducting Experiment 3 with a third group of rats on an enhanced maze, which includes both proximal and distal navigational cues. A radial maze, while providing distal stimuli, does not have specific proximal cues. Natural environments, however, provide animals with cues at various distances. These experiments are extending our knowledge of whether or not the spatial domain does assist rats on tests of relational (emergent) symmetry. If animals such as rats are incapable of relational symmetry in a wide array of domains, this may reflect a general difference in human and animal cognition.

References

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