Same-Different Texture Discrimination in
Pigeons:
Testing Competing Models of Discrimination and Stimulus Integration
Robert G. Cook & John T. Wixted
The choice behavior of six pigeons performing a multidimensional Same-Different texture discrimination was examined. On each trial, they had to choose among two "choice" hoppers depending on whether a color, shape, or redundant (color & shape) target signal was present or not in a textured stimulus. ROC curves were produced by variations in the a priori signal presentation probabilities across conditions. Quantitative analyses of these ROC curves were used to evaluate different competing theories of discrimination (signal detection versus high threshold/default response models) and information integration (independent observations, additive integration, unidimensional models). The results suggested the structure of the pigeons= choice behavior in this Same-Different discrimination was best described by an unequal variance signal detection model involving a unidimensional evidence variable (e.g., degree of difference).
Examples of the Same and Different Texture Displays tested with the pigeons
Dynamic
Texture Stimuli 
Same-Different
& SDT 
Same-Different
w/ Multiple Stimuli
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08/25/99