Figure 4.

Design of different geometric experiment types. (A,B) are examples for direct estimation of amplitude (with fixed frequency) and frequency (with fixed amplitude) magnitude, respectively; the participants need to assess the corresponding magnitude in the “Test sample” (right) on the basis of the reference shapes (left and middle). (C) shows an example of a sawtooth amplitude calibration against a sinusoidal reference; the task is to select the test shape (a–e) whose amplitude is perceived as the closest to the “Reference” shape (left).