Animal cognition is the title given to a modern approach to the mental capacities of non-human animals. It has developed out of comparative psychology, but has also been strongly influenced by the approach of ethology, behavioral ecology, and evolutionary psychology. The alternative name cognitive ethology is therefore sometimes used; and much of what used to be considered under the title of animal intelligence is now thought of under this heading.
In practice, animal cognition mostly concerns mammals, especially primates, cetaceans and elephants, besides canidae, felidae and rodents, but research also extends to non-mammalian vertebrates such as birds such as pigeons, lizards or fish, and even to non-vertebrates (cephalopods).
In 1907, Clever Hans, a horse that was claimed to have been able to perform arithmetic and other intellectual tasks made the New York Times.. After formal investigation in 1907, psychologist Oskar Pfungst demonstrated that the horse was not actually performing these mental tasks, but was watching the reaction of his human observers. The horse was responding directly to involuntary cues in the body language of the human trainer, who had the faculties to solve each problem. The trainer was entirely unaware that he was providing such cues.
For most of the twentieth century, the dominant approach to animal psychology was to use experiments on intelligence in animals to uncover simple processes (such as classical conditioning and operant conditioning) that might then account for the apparently more complex intellectual abilities of humans. This approach is well summarised in the mid-century book by Hilgard (1958), but its reductionist philosophy was combined with a strongly behaviorist methodology, in which overt behavior was taken as the only valid data for the study of psychology, and in its more extreme forms (the radical behaviorism of B. F. Skinner and his experimental analysis of behavior) behavior was taken as the only topic of interest. In effect, the mental processes that humans experience in themselves were viewed as epiphenomena (see, for example, Skinner, 1969).
The success of cognitive psychology in addressing human mental processes, which began in the late 1950s and was proclaimed by Neisser (1967), led to a re-evaluation of the research paradigm, and researchers began to address animal mental processes from the opposite direction, by taking what is known about human mental processes and looking for evidence of comparable processes in other species. In a sense this was a return to the approach of Darwin's protegé George Romanes (e.g. 1886), arguably the first comparative psychologist of the modern era. However, whereas Romanes relied heavily on anecdote and an anthropomorphic projection of human capacities onto other species, modern researchers in animal cognition are in most cases firmly behaviorist in methodology, even though they differ sharply from the behaviorist philosophy. There are some exceptions to the rule of behaviorist methodology, such as John Lilly and, some would argue, Donald Griffin (e.g. 1992), who have been prepared to take a strong position that other animals do have minds and that humans should approach the study of their cognition accordingly. However, their claims have not found wide acceptance in the scientific community, though they have attracted an enthusiastic following among lay people.