The origins and current status of comparative cognitive psychology are examined. Great strides have been made in the last 20 years, but two problems are identified as obstacles to future progress. One is the very limited number of species studied by comparative cognitive psychologists. The second is the conflict between the increasing use of complex stimulus discriminations and the need for precise stimulus control in animal experiments. An expanded examination of more species as selected by phylogenetic and ecological considerations and an unwavering demand for the experimental identification of the controlling features of complex discriminations are suggested as solutions to these difficulties.
Complex stimulus control in humans: Merging functional and equivalence classes
