1. Feature memorization in pigeon concept formation;Greene,1983
2. Stimulus selection and feature selection in learning and behavior;Hearst,1978
3. Absence as information: Some implications for learning, performance, and representational processes;Hearst,1984
4. Acquisition, generalization, and discrimination reversal of a natural concept;Herrnstein;Journal of Experimental Psychology: Animal Behavior Processes,1979
5. Fish as a natural category for people and pigeons;Hernnstein,1980