Table 4.

Comparisons of variables of interest (based on principal component analysis) across the best (n = 7) and worst (n = 7) learners among aged animals

^aFactor scores (derived from the principal component analysis summarized in Table 1) provide an estimation of animals’ general learning ability, where values below zero reflect overall performance better than the group median, and values above zero reflect overall performance that is worse than the group median. On all variables, animals were divided into the best and worst general learning abilities (the top and bottom ∼25% of factor scores). Presented values are means ± standard errors. Since factor scores were obtained from the top and bottom of the range of scores, a statistical comparison of factor scores was not justified; however, inspection of standard errors indicates a good separation of the best and worst learners.