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. Author manuscript; available in PMC: 2011 Oct 1.
Published in final edited form as: Behav Processes. 2010 Aug 11;85(3):226–235. doi: 10.1016/j.beproc.2010.07.012

Figure 1.

Figure 1

Top panel: The stimulus classes hypothesized to develop from the reinforced sample-comparison successive matching sequences in hue-form symbolic matching, hue identity matching, and form identity matching. Ellipses highlight common class members. Bottom panel: Two 4-member stimulus classes hypothesized to arise from the merger of the stimulus classes shown in the top panel via their common elements. Arrows indicate sample-comparison sequences to which pigeons should preferentially respond in a symmetry test assuming reinforced red sample – triangle comparison and green sample – horizontal sequences in training. R = red, G = green, T = triangle, H = horizontal, 1 = first ordinal position within a matching trial, 2 = second ordinal position within a matching trial.