Examining Individual Differences and Exploratory Behavioral Responses in Prairie Voles: In Search of a Behavioral Syndrome

Behavioral syndromes, also called behavioral phenotypes or profiles, are defined as correlations between behaviors in different environmental contexts or testing situations. Despite the popularity of behavioral syndrome research, there is no universally accepted method for measuring and determining what behavioral syndrome a subject demonstrates.  My objective was to determine if prairie voles, Microtus ochrogaster, demonstrate correlated behaviors in different situations within a single context – exploration. Exploratory behavior responses were examined in three novel situations: an open-field with novel objects, a two-way novel choice apparatus, and a complex maze. For each situation, behavioral responses were identified by key dependent variables determined by Principal Components Analysis. Three different exploratory responses emerged: the open-field test with novel objects measured interactive behavior, the complex maze measured general activity behavior, and the two-way novel choice test measured proactive/reactive behavior in response to novel environments. For each test, subjects were ranked from low to high exploratory tendency, thus creating three exploratory behavioral responses. The exploratory behavioral responses were compared and there was no correlation across tests, thus providing no evidence of an overall exploratory behavioral syndrome in this species. In light of these findings, each exploratory test appears to measure different and uncorrelated aspects of exploratory behavior. Recently, an increasing number of studies of behavioral syndromes similarly have failed to find a correlation of behaviors across tests or contexts. These results raise questions about the ability to identify personality types in animals and the validity of behavioral syndromes as a general attribute of animal behavior.