Results for all seven subjects tested, means and standard errors of the means for the sample, as well as estimate results for an “average subject” (ASU; see text for details).

Subjects were tested using Gábor patterns at four different Michelson contrasts. To estimate spatial extent entropy (S2), the spatial frequency was kept constant at 0.4 cycles/degree while the spatial standard deviation was varied around 1 deg. To estimate spatial frequency entropy (F), the spatial frequency was varied around 0.4 cycles/degree while the spatial standard deviation was kept constant at 1 deg. Joint entropy (J) was obtained by multiplying the spatial frequency entropy times the square root of the spatial extent entropy to account for the use of Gábor stimuli comprising 2D Gaussian envelopes and 1D sine wave gratings (J = F x S). For some subjects and stimulus conditions it was not possible to provide a good fitting to the data points (empty cells). However, for the ASU estimates, all data points were taken in consideration.