Initial analyses for each dependent variable were by two-way ANOVA with strain and sex as independent variables. Narrow sense heritability (h2) was estimated as the percentage of total trait variance accounted for (R2) by inbred strain in a one-way ANOVA with strain as the only factor. To correct for the varying influence of locomotion in the tasks, residual scores were obtained from the regression of the principal dependent variable from each task (number of rears, number of head dips, percent preference for objects, or time spent in the novel compartment) on locomotion as measured in each task. Strain means for this residual score were then correlated. Scores for spontaneous alternation were not corrected because activity data were not collected in this task.
