Figure 1.

(A) Schematic representation of the contrast sensitivity function, which was constructed using the inverse of measured contrast thresholds, operationally defined as the point of inflection in the psychometric function, at each spatial frequency. The contrast sensitivity function has a maximum value at intermediate spatial frequencies, and decreases with both lower and higher spatial frequencies. In the quick contrast sensitivity function method, the spatial contrast-sensitivity-function parameters (the peak gain, γmax; the peak spatial frequency fmax; the bandwidth β, which describes the function's full width at half maximum; and the low-frequency truncation level δ) are directly estimated via Bayesian adaptive inference rather than measuring multiple contrast thresholds at each spatial frequency based on psychometric functions. The dashed line indicates predicted contrast sensitivities before truncation (B) Conditioning phase trial sequence. (C) Orientation identification task trial sequence. Note that stimuli are not drawn to scale here.