Pinna movements (right pinna, cat 21) during 1 day of testing in response to paired-source stimuli with interstimulus delays (ISDs) in the summing localization range. A: speakers were located along the horizontal meridian at (−18, 0°) and (+18, 0°) with ISDs = +100 μs (speaker A leading, thin traces) and ISDs = −100 μs (speaker B leading, thick traces). B: speakers were located along the vertical meridian at (0, +18°) and (0, −23°) with ISDs = +100 μs (speaker A leading, thin traces) and ISD + −100 μs (speaker B leading, thick traces).