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. Author manuscript; available in PMC: 2015 Mar 1.
Published in final edited form as: Behav Processes. 2013 Nov 27;103:156–164. doi: 10.1016/j.beproc.2013.11.004

Figure 4.

Figure 4

Pigeons chose between two alternatives that were distinguished by discriminative stimuli (a vertical or a horizontal line). Choice of one alternative was followed either by a stimulus (e.g., red) on 20% of the trials that was always followed by 10 pellets of reinforcement or by a different stimulus (e.g., green) on 80% of the trials that was never followed by reinforcement. Choice of the other alternative was followed by either of two stimuli (blue or yellow) both of which always were followed by 3 pellets of reinforcement. Spatial location and colors were counterbalanced.