Bayesian adaptive estimation of the contrast sensitivity function: The quick CSF method

Abstract

The contrast sensitivity function (CSF) predicts functional vision better than acuity, but long testing times prevent its psychophysical assessment in clinical and practical applications. This study presents the quick CSF (qCSF) method, a Bayesian adaptive procedure that applies a strategy developed to estimate multiple parameters of the psychometric function (A. B. Cobo-Lewis, 1996; L. L. Kontsevich & C. W. Tyler, 1999). Before each trial, a one-step-ahead search finds the grating stimulus (defined by frequency and contrast) that maximizes the expected information gain (J. V. Kujala & T. J. Lukka, 2006; L. A. Lesmes et al., 2006), about four CSF parameters. By directly estimating CSF parameters, data collected at one spatial frequency improves sensitivity estimates across all frequencies. A psychophysical study validated that CSFs obtained with 100 qCSF trials (~10 min) exhibited good precision across spatial frequencies (SD < 2–3 dB) and excellent agreement with CSFs obtained independently (mean RMSE = 0.86 dB). To estimate the broad sensitivity metric provided by the area under the log CSF (AULCSF), only 25 trials were needed to achieve a coefficient of variation of 15–20%. The current study demonstrates the method’s value for basic and clinical investigations. Further studies, applying the qCSF to measure wider ranges of normal and abnormal vision, will determine how its efficiency translates to clinical assessment.

Sensory adaptation as optimal resource allocation

“…Stimulus selection was controlled by a generalized procedure of Lesmes et al (25). The procedure allowed us to estimate the entire sensitivity function from every observer within one experimental session, repeated several times for each observer.…”

“…3A for experiment 2. Stimulus parameters for every trial were sampled from the stimulus grid using an efficient Bayesian procedure that was a generalization of the quick CSF procedure (25) to stimulus dimensions f s and f t . This procedure greatly accelerated measurement of sensitivity using an information gain algorithm (53, 54) that estimated parameters of sensitivity functions directly, rather than estimating sensitivities at individual stimulus conditions.…”

“…Each procedure used the same prior distribution defined as in equation A1 in ref. 25. Sessions were repeated three times for every observer.…”

Mapping the structure of perceptual and visual–motor abilities in healthy young adults

“…Contrast Sensitivity was measured at 6 and 18 cpd using the Sensory Station, and as a continuous spatial frequency function using the QuickCSF Task (Lesmes, Lu, Baek, & Albright, 2010) in 108 of the participants. Consistent with the literature (e.g., Hashemi et al, 2012;Robson, 1966), Contrast Sensitivity measured by the Sensory Station was significantly better at 6 cpd than at 18 cpd, (t(229) = 35.289, p b 0.001).…”

Limits of Spatial Vision in Sumatran Orangutans (Pongo abelii)

“…The CSF is now understood to reflect the envelope of sensitivities of multiple spatial channels within the visual pathway, carrying information at several different spatial scales (Campbell & Robson, 1968;Lesmes, Lu, Baek, & Albright, 2010;Wilson & Giese, 1977) and thus, gives a more complete picture of spatial sensitivity. CSFs have been measured in a wide range of species including cats, pigeons, several rodents and several primates (see Uhlrich, Essock, & Lehmkuhle, 1981, for review, and Table 1 for primates), and the general form of the CSF is similar across species, if normalized for maximum sensitivity and scaled in terms of distance from the peak frequency in octaves (factors of 2) (Uhlrich et al, 1981).…”