Figure 1.

The pCSF test. (A) Hardware. Participants pressed equiluminant Gabor patches of variable frequency and contrast as they bounced around the screen. The maximum of five Gabors is shown here for effect, but typically only one or two (or zero) were displayed at any one time, and often some Gabors were suprathreshold. (B) Psychophysical algorithm. Stimulus selection and model fitting was performed using a Maximum Likelihood (QUEST+) algorithm, which attempted to fit the three-parameter model shown graphically here (and described formally in Equation 1). (C) Example CSFs for a single child aged 5.2 years, for both their amblyopic eye (red dashed line) and fellow eye (blue solid line). The shaded region indicates the area under the contrast sensitivity function (AUCSF) summary measure. A higher AUCSF value indicates greater overall contrast sensitivity.