Dynamic properties of internal noise probed by modulating binocular rivalry
Fig 5
Summary of model behaviour for internal noise amplitude and spectral slope estimation.
(a) The histograms of dominance durations for each spectral slope (ɑ = 0.0–2.0) and level of internal noise (SD = 1%– 64%). Within each subplot, the uppermost (green shaded) histogram shows the equivalent human data for a stimulus temporal frequency of 1/8Hz and a contrast modulation of SD = 16%. The solid vertical green line marks the average dominance duration for human observers. Histograms below show model dominance duration distributions for each internal noise level. (b) Average dominance durations of the model for each spectral slope (coloured lines). The green line and shaded area mark human average dominance duration and ±1SE of the mean, respectively. Average dominance duration was affected by internal noise once its standard deviation was equivalent to 4% contrast. Noise with steeper slopes (ɑ = 1.5–2.0) increased mean dominance duration as a function of noise contrast, while noise with shallower slopes decreased mean dominance duration. (c) Response consistency decreased as a function of internal noise contrast for all spectral slopes. The green line and shaded area mark human observer average consistency and ±1SE of the mean, respectively. For all ɑ>0, response consistency reached human levels at an internal noise contrast of 16%.