INTERPRETATION OF KERNELS .2. SAME-SIGNED 1ST-DEGREE AND 2ND-DEGREE (MAIN-DIAGONAL) KERNELS OF THE HUMAN PUPILLARY SYSTEM

The human pupillary system exhibits a dynamic asymmetry between responses to on and off stimuli. From pupil random-light-stimulus experimental data and by frequency-domain analysis, we obtained the 1st- and 2nd-degree kernels of the human pupillary system. The pupil kernel model produces responses to on and off pulse and step stimuli that are similar to pupil experimental responses. Extrapolation from a power-series representation of the pupil kernels, using only slope and curvature values to replace the major effects of the 1st- and 2nd-degree kernels respectively, indicates that both 1st and 2nd-degree main-diagonal kernels should have the same (negative) sign in order to give the kernel model dynamic asymmetry of response. Indeed, the experimentally derived pupil 1st- and 2nd-degree kernels were found to have the same sign. This result provides insight into the relationship between signs of derived kernels and the response nonlinearities of a physiological system. © 1979.