Fig. 1. The tymbal phonoresponse of Cycnia tenera. (A) Oscillogram of one stimulus pulse in a pulse train and the tymbal sounds as a series of clicks within a single modulation cycle (Blest et al., 1963). (B) The habituation/generalization (H/G) paradigm. (Top) Initial stimulus pulse train and moth phonoresponse. (Middle) Tenth pulse train where the moth has completely habituated. (Bottom) Test pulse train stimulus showing lack of generalization in the moth's phonoresponse. (C) Measurements taken from one H/G trial. Responses were the number of tymbal modulation cycles per stimulus pulse train (normalized to the percentage change from initial response). Habituation was determined if the slope of a linear regression applied to the response decrease was significantly less than 0; lack of generalization (i.e. expressed stimuli discrimination) was determined from pooled habituated animals if the test stimulus response was significantly greater than the average of the last habituated responses.