Fig. 1.

Time course of performance of rat L in one session (duration 60 min, 858 trials) when discriminating between upward and downward FM tones of different sweep speed (20 to 1,000 octaves/s). The animal was well-trained in the discrimination paradigm (2AFC-procedure). Stimuli were presented with the method of constant stimuli. a Time course of trial frequency depicted as number of trials in 5-min blocks. The animal was constantly performing at a high level of trial frequency for about 50 min. b Time course of the percentage of hits and break errors during the session. Remember that hit rate level is determined by the mixture of easy and hard to discriminate FM stimuli (13 different sweep speeds).