Figure 2. Discrimination gradients depicting ability to distinguish vocal calls for birds of different ages.
(A) Behavioral discrimination scores (mean ± SEM) are plotted for three age groups of birds that were habituated to a call stimulus with a FF of 480 Hz and then tested with novel calls ranging in FF from 410 to 550 Hz (left panel); three separate age groups were habituated to a call stimulus of 650 Hz and tested with novel calls ranging from 550 to 750 Hz (right panel). (B) Neural discrimination scores (mean ± SEM) for three separate experiments in which different age groups were habituated to call stimuli with a FF of either 480, 650, or 800 Hz and then presented with novel test calls that varied in FF. Discrimination score: 0.0 = no different from habituated stimulus, 1.0 = completely discriminated; see Methods.