A Cognitive Test Battery to Assess General Intelligence in the Pigeon (Columba livia)
The study of intelligence in humans has been ongoing for over 100 years, including the underlying structure, predictive validity, related cognitive measures, and source of differences. One of the key findings in intelligence research is the uniform positive correlations among cognitive tasks. Factor analysis consistently extracts one factor that can account for approximately half of the variance in performance. This factor is termed g and all cognitive tasks positively load onto this factor. This has been replicated with every cognitive test battery in humans. Nevertheless, many other aspects of intelligence research have revealed contradictory lines of evidence. Recently, cognitive test batteries have been developed for animals to examine similarities to humans in cognitive structure. When mice and some avian species are assessed with cognitive test batteries, performance positively correlates and the first component extracted has similar properties to g. There are some limitations to the species tested thus far, including comparability in the cognitive domains assessed across species and homogeneous samples. The pigeon is an ideal subject to overcome these issues since pigeons, humans, and other primates are frequently given similar tasks. We created a test battery for pigeons that assessed different cognitive domains, including associative learning, short term memory, cognitive flexibility, and reaction time. This test battery was administered to 23 subjects that ranged in age from 6 months to 18 years old. The tasks included were sufficiently sensitive to detect individual differences, while still being reliable measures of performance. Despite the strengths of the test battery, we did not consistently extract a g like factor. Analyses indicated a two-component structure, where the associative learning and reaction time tasks loaded onto component 1, while short term memory and cognitive flexibility tasks loaded onto component 2. While it is impossible to determine what these components represent from the results of these experiments alone, we speculated that these components could reflect reliance on different underlying cognitive abilities, degree of automaticity, and sensitivity to age related decline. Additional research, including administering test batteries to other species, will be necessary to fully understand why pigeons show two-components instead of g.