Figure 3.

Acquisition of song recognition. Mean d-prime (±sem) shown over the course of successive 100-trial training blocks showing the gradual improvement in classification of songs from two different singers. Performance is above chance after seven blocks, which includes acquisition of all operant task requirements (e.g., when to peck) as well as knowledge about the stimuli. Mean (±sem) performance at asymptote, just prior to testing (see methods), is shown by the black bar on the right.