Psychophysical derivation of the impulse response through generation of ultrabrief responses: complex inverse...

A new technique is presented for the psychophysical measurement of the response phase that requires no assumptions of the relation between the phase and amplitude components of the frequency response. The amplitude attenuation is measured by a standard threshold paradigm and is then compensated for by increasing harmonic strength in proportion to the visual attenuation. Then the phase of each frequency component is adjusted to maximize the internal response amplitude. The amplitude and phase values may be converted by inverse Fourier transformation into the estimated visual impulse response in any stable set of stimulus conditions and are insensitive to a wide variety of response nonlinearities. A key aspect of the phase measurement technique is the generation of a stimulus to obtain the minimum time spread of the internal response, creating a briefer response than for any other stimulus.