Pigeons were monocularly trained on single stimulus training (SD : 135° tilted line), interdimensional discrimination (SD : 135°, SΔ : blank key), intradimensional discrimination (SD : 135° SΔ : vertical line) or mirror image discrimination (SD : 135°, SΔ : 45°). Following these training, they were subjected to a stimulus control test with 135° line and 45° line. Subjects in the discrimination groups indicated the mirror image reversal effect, that is, they emitted more responses to the 45° line than to the 135° line in the test with the untrained eye. Whereas, pigeons trained on the single stimulus training responded equally both to the 135° and to the 45°. Stimulus control tests with radius stimuli clarified that subjects which showed the reversal effect discriminated the tilted line on the basis of the eye being used.