 Between 1972 and 1977, Koko was administered several infant IQ tests, including the Cattell Infant Intelligence Scale and form B of the Peabody Picture Vocabulary Test.She achieved scores in the 70–90 range, which is comparable to a human infant that is slow but not intellectually impaired.According to Francine Patterson, however, it is specious to compare her IQ directly with that of a human infant because gorillas develop locomotor abilities earlier than humans and many IQ tests for infants require mostly motor responses.