Fig. 2.

Ability to discriminate FM sweep direction in logarithmic FM tones spanning five octaves by rats. Rates of correct responses (hit rate) are shown for sweep speeds between 20 and 1,000 octaves/s. Psychometric functions fitted to the data are depicted for five individual animals (rat L–rat R). Threshold sweep speed values (in octaves/s) for two different threshold measures as extracted from the psychometric functions are given in each panel below the animal name. Upper value: threshold at 0.75 hit rate, lower value: threshold sweep speed at the inflection point of the psychometric function (i.e., in the middle between minimum and maximum hit rates).