Figure 1

Spectrograms representing examples for aggression (A, B), and response (C, D), call stimuli of different affect intensity. Calls of high affect intensity are termed strong, while calls of low affect intensity are termed weak. Exemplars in A, B, C, and D were used as test stimuli in reciprocal experiments. E represents an original recording of a strong response call; please note interfering echolocation calls from the interaction partner (for examples see arrows), disturbing echoes and a recording artefact at about 92 kHz. F shows the spectrogram of the control stimulus of low frequency. The dotted line in C and F at 10 kHz is given to make the frequency shift between the respective response call stimuli more obvious.