Simultaneous Pattern Discriminations by Pigeons Reveal Absence of Mirror-Image and Left-Right Confusions
Abstract
In a simultaneous discrimination task, pigeons were first trained with two patterns: one rewarding (A+) and the other unrewarding (B-) that contained the same components (the symbols: c, d, ■ and <) but displayed in a different spatial layout. They were then tested for their choices of patterns: (1) A+ vs. its mirror image (MI); (2) A+ vs. its left-right reversal (LR); (3) MI vs. other layouts (OL) of the symbols; (4) LR vs. OL. In the first two conditions, A+ was chosen over its MI and LR reversal (i.e., no MI or LR confusions were found). In the last two conditions, MI and LR were not chosen over the OL, that is, they were not treated as substitutes for the A+. On the contrary, the OL stimuli were chosen over the transformations of A+. In all cases, the discriminations revealed a failure to confuse the A+ with its transformations, as predicted from work showing that the position of pattern components is important in pattern recognition.