Lionello, K.M., & Urcuioli, P.J. (1998).
Control by sample location in pigeons matching to sample.
Journal of the Experimental Analysis of Behavior,
70, 235-251.
Three experiments assessed the impact of sample location in pigeons' matching to sample.
Experiments 1 and 2 demonstrated that after line or hue identity matching was acquired to high levels of accuracy with
center-key samples, varying sample location across the three keys disrupted performances. The drop in accuracy occurred
following both zero-delay and simultaneous training and was mostly confined to trials in which the sample appeared on a
side key. Experiment 3 attempted to diminish control by location by training birds to match samples that could appear in
any location prior to center-key sample training and moving-sample testing with another set of stimuli. In testing, all birds
performed accurately on center-sample trials and on side-key sample trials in which the matching choice appeared on the
center key. Accuracy was below chance, however, on side-key sample trials in which the matching choice appeared on the
other side key. One implication of the persistent control by sample location in the three-key paradigm is that it precludes the
possibility of symmetry because symmetry tests require a change in the locations at which samples and comparisons appear.
Key words: sample location, matching to sample, moving-sample tests, symmetry, pecking, pigeons