Figure 2.

Examples of stimulus displays presented to the pigeons. (A) An example of a training display used in Experiment 1. The circular stimulus at the top of the panel served as a sample; the pair of bars at the bottom of (A) show the rewarded comparison stimulus on the left (an attributional and relational match to the sample) and non-rewarded comparison on the right (non-matching to the sample in both attributional and relational levels). (B) An example of a test display from Experiment 1. The comparison on the left was an attributional match to the sample, the comparison on the right was a relational match to the sample. (C) Example of a test display from Experiment 2. Both comparisons were an attributional match to the sample, but only the left-hand comparison was a relational match to the sample. (D) Example of a test display from Experiment 3. Neither comparison was an attributional match to the sample; but only the left-hand comparison was a relational match to the sample. (E) Example of a test display from Experiment 4. Both comparisons were an attributional match to the sample, but only the right-hand comparison was a relational match to the sample. The orientations of the bars in the left-hand comparison were oriented in the same overall shape as the colored halves of the sample stimulus. (F) Example of a test display from Experiment 5. The comparison on the left was an attributional match, while the comparison on the right was a relational match on probe tests involving novel color elements.