Novel environment preference, which seemed to us to be the trait that most clearly reflected the actual preference for novelty, was moderately influenced by genotype (R2 = 0.33). In a similar apparatus, but using a different procedure, Belzung and her collaborators (17, 25, 26) observed some genotypic differences in a free exploratory procedure, which generally indicated few strain differences, although more differences among other inbred strains were found in response to predator odor exposure. These results imply that genotype might play a relatively small role in the expression of novel environment preference, although variants of this task appear to be sensitive to different factors, such as age at weaning or other experiences (27–30). Data in Fig. 1 and Table 4 show that spontaneous alternation is largely unrelated to all of the other tasks.
