In Experiments 1 and 2, rats were trained in a Morris water maze to locate a hidden platform, the location of which in the circular pool was defined by four visual landmarks (A, B, C, and D), spaced at equal intervals around the edge of the pool. Control animals were trained with these four visual landmarks only. But for animals in the overshadowing groups, an auditory component, X, was added to Landmark D. Test trials, given at the end of training, consisted of placing the rat in the pool with no platform present and recording the time rats spent in the platform quadrant. In Experiment 1, the overshadowing group spent less time in the platform quadrant than controls when tested with D, but the two groups performed equally well on test trials that did not use D. We conclude that the auditory Component X overshadowed the visual Landmark D. In Experiment 2, we obtained evidence of reciprocal overshadowing, of D by X and of X by D. The results of Experiment 3 suggested that an appeal to generalization decrement might not be sufficient to explain these overshadowing effects.
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This research was supported by grants from the U.K. Biotechnology and Biological Sciences Research Council to N.J.M., and from the Spanish Ministerio de Educación y Ciencia (DGICYT PB97-0965) to V.D.C. The authors thank Antoni Cosculluela for statistical advice.
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Sánchez-Moreno, J., Rodrigo, T., Chamizo, V.D. et al. Overshadowing in the spatial domain. Animal Learning & Behavior 27, 391–398 (1999). https://doi.org/10.3758/BF03209976
- Test Trial
- Taste Aversion
- Swimming Pool
- Animal Behavior Process
- Hide Platform