Same-different conceptualization by baboons (Papio papio): The role of entropy

The authors trained 6 baboons (Papio papio) to make 1 of 2 report responses to 16-icon same arrays versus 16-icon different arrays. In the same arrays , the icons were all the same as one another, whereas in the different arra ys the icons were all different from one another. In Experiment 1. the babo ons discriminated the same arrays from the different arrays, and they trans ferred their discriminative responding to arrays of novel icons. In Experim ents 2 and 3, the baboons exhibited strong sensitivity to the degree of dis play variability when they were shown mixed arrays that comprised some same and some different items. The information theoretic measure "entropy" syst ematically described these results and outperformed several rival metrics. Finally, in Experiments 4 and 5, the baboons' responses to displays that co ntained jittered and blurred icons suggested that their same-different conc eptual behavior was not based on the spatial orderliness of the visual arra ys.