[Behavior-genetic analysis of responses in runway test as measures of emotional reactivity in rats: I.- phenotypic variations and heritability estimates based on offspring-parents regressions (author's transl)].

Individual differences of emotional reactivity were estimated from 6 kinds of responses measured in the Runway Test (modified ("Timidity Test") in 974 random-bred albino rats. 3 different estimates of heritability of these responses were calculated from the regressions of offspring on dam, sire, and midparent. The types and degree of the phenotypic variations are very different among the responses measured. Heritability estimates of 2 kinds of responses which are related to the behavior going to the remotest part of runway from starting box were relatively higher (.30-.55). Heritability estimates of starting latency, time in the starting box, and the number of sections rats traversed were medium (.20-.40). The estimates from defecation scores had lowest (.10-.30).