Comparison of three analytical approaches to assess temperament dimensions in nonhuman animals

A critical aspect in the research about behavioral individual differences is the researchers’ decision of which statistical methods to use to reduce the dimensionality of observed behavioral data. Our aim was to compare the main behavioral dimensions obtained from three different data reduction techniques: the Feaver’s Method, Factor Analysis, and Principal Component Analysis. Three behavioral tests were carried out with 13 individuals of Amazona vinacea and 12 of Psittacara leucophthalmus species: reaction to an unknown person test, the reaction to potential predator test and the novel object test. We extracted the main behavioral dimensions using the three methods. Then we applied the Pearson’s correlation to test the relationships between the main dimensions found. The first Principal Component, the Factor 1, and the dimension 1 of Feaver’s Method were composed of behavioral variables reflecting ‘vigilance’. Variables in second Principal Component, Factor 2 and dimension 2 of Feaver’s Method reflected ‘fearfulness’. A strong correlation was found between the first Principal Component and dimension 1 of Feaver’s Method (r = 0.90), but not with Factor 1 (P > 0.05). Moderate correlations were found between second dimension with three methods. We conclude that PCA and Feaver’s Method generate similar results for the first principal dimension, but not for the second dimension, and Feaver’s Method seems to be a better predictor of this aspect of parrots’ behavioral individual differences for small samples sizes.