Three-choice Discrimination Task Research Articles

Pigeon perception of letters of the alphabet.

In a three-choice discrimination task three pigeons learned to distinguish each letter of the alphabet from all other letters. Errors during learning were based on 54 presentations of each target letter with every other letter. The errors were used to scale letters in a multidimensional similarity space and to associate them in hierarchical clusters. The results resembled those generated from similarity judgments by humans, suggesting cross-task and cross-species generality in processes of letter discrimination.

Behavioral measurements of rat spectral sensitivity

Behavioral measurements of visual sensitivity were obtained from hooded rats on a threechoice discrimination task. Increment threshold measurements reveal the occurrence of a distinct Purkinje shift. Photopic spectral sensitivity functions for this animal have peaks at 500 and 580 nm. The results of chromatic adaptation suggest that this photopic sensitivity function results from interactions between two mechanisms with peak sensitivities near 520 and 540 nm. Along with previous behavioral and electrophysiological results, these findings suggest that the rat possesses at least three different spectral mechanisms—a scotopic mechanism with a peak sensitivity at 500 nm and two photopic mechanisms whose peak sensitivities may be about 520 and 540 nm.