We determined DeLange curves with and without external temporal noise at eccentricities of 0 – 70 deg by measuring flicker sensitivity at 1 – 45 Hz for sharp-edged M-scaled spots with an equiluminous surround. Without noise, flicker sensitivity at high frequencies increased with eccentricity but remained unchanged at low frequencies. In strong noise, flicker sensitivity was independent of eccentricity. The only exception was 70 deg where sensitivity was reduced at 1 – 3 Hz with and without noise. The data at each eccentricity are well described by our flicker-sensitivity model (Rovamo et al, 1996 Vision Research 36 3767 – 3774) comprising (i) low-pass filtering by the modulation transfer function (MTF) of the retina, (ii) filtering in direct proportion to temporal frequency by the high-pass MTF of the retina and subsequent neural visual pathways, (iii) addition of white internal neural noise, and (iv) detection by a temporal matched filter. When interpreted in the context of the model, our results mean that while the high-pass filter and the magnitude of internal noise remained unchanged across eccentricities, the bandwith of the low-pass filter increased with eccentricity and at 70 deg eccentricity the efficiency of the detecting mechanism in the brain was reduced at 1 – 3 Hz. The increase in the bandwidth of the low-pass filter is in agreement with the eccentricity-dependent changes in the retinal function as revealed by the electroretinogram (ERG).
