The structure of equine personality
The current study was designed to investigate the structure of equine personality. Two personality questionnaires were replicated from previous studies and implemented simultaneously to test the theory that different questionnaires may extract different personality structures. Breed and sex differences were also hypothesized to be significantly different for some personality dimensions. A total of 827 horses were rated on a 90-item personality questionnaire. Participants were recruited online via email and completed the survey at their own convenience. An additional 121 respondents rated a horse that had already been rated; these results were used to calculate inter-rater reliability. After data collection was complete, the two questionnaires were separated for individual analyses. The first, a five-factor model (FFM) adapted by Morris et al. (2002) from the short form NEO-PI-FFI, consisted of 60 items. Seventeen of these items were removed in the current study due to a large percentage of people who responded "don't know" to the item. The FFM questionnaire was put through a Principal Components Analysis, which extracted eight factors: Neuroticism, Active, Conscientiousness, Agreeableness, Openness, Social Extraversion, Temperamental, and Disciplined. Significant sex differences were found in the components Neuroticism, Openness, Social Extraversion, and Temperamental. Breed differences were found in the component Active. The second questionnaire (the Horse Personality Questionnaire; HPQ) consisted of 30 Behaviorally Defined Adjectives, adapted by Lloyd et al. (2007) from Stevenson-Hinde et al. (1978). Six of these items were removed from the current study when they either failed to load significantly onto any component in the PCA or reduced the alpha level of the component onto which they loaded. The final PCA resulted in six personality components: Anxiousness, Dominance, Sociability, Protection, Excitability, and Inquisitiveness. Sex differences were found in Protection and Sociability. Excitability was the only component with significant breed differences. Each FFM component correlated well with at least one HPQ component except for Inquisitiveness on the HPQ, indicating convergent validity of the scales. The HPQ component Anxiousness was significantly correlated with the FFM components Neuroticism and Conscientiousness. Both Dominance and Protection from the HPQ correlated with Agreeableness on the FFM. Sociability on the HPQ correlated negatively with Social Extraversion on the FFM. The second-highest correlation among the paired components was between Excitability on the HPQ and Active on the FFM. Limitations of the current study included low diversity of horses with different uses, as well as low diversity of different relationships between horse and rater. The removal of 17 items from the FFM may have significantly altered the outcome of the PCA, and the sample size for stallions and individual breeds was low. Future work should focus on correcting these limitations and comparing personality results to genetic and behavioral research.