PurposeThe Bayesian adaptive quick contrast sensitivity function (qCSF) method with a 10-letter identification task provides an efficient CSF assessment. However, large populations are unfamiliar with letters and cannot benefit from this test. To overcome the barrier, we conducted this study.MethodA new font for digits (0∼9) was created. The digits were then filtered with a raised cosine filter, rescaled to different sizes to cover spatial frequencies from 0.5 to 16 cycles per degree (cpd), and used as stimuli in a 10-alternative forced choice (10AFC) digit identification task. With the 10AFC digit identification task, the CSFs of five young and five old observers were measured using the qCSF and Psi methods. The estimates from the latter served as reference.ResultsThe new digit font showed significantly improved similarity structure, Levene's test, F(1, 88) = 6.36, P = 0.014. With the 10-digit identification task, the CSFs obtained with the qCSF method matched well with those obtained with the Psi method (root mean square error [RMSE] = 0.053 log10 units). With approximately 30 trials, the precision of the qCSF method reached 0.1 log10 units. With approximately 75 trials, the precision of the CSFs obtained with the qCSF was comparable to that of the CSFs measured by the Psi method in 150 trials.ConclusionsThe qCSF with the 10 digit identification task is validated for both young and old observers.Translational RelevanceThe qCSF method with the 10-digit identification task provides an efficient and precise CSF test especially for people who are unfamiliar with letters.

PurposeThe contrast sensitivity function (CSF) is measured traditionally with grating stimuli. Recently, we introduced a new set of digit stimuli to improve the efficiency of CSF tests for people unfamiliar with the Latin alphabet. Given the significant differences between grating and digit stimuli, we conducted this study to evaluate whether the estimated CSFs from the digit test are equivalent to those from the grating test.MethodsThe CSFs of five young (with Psi) and five older (with quick CSF [qCSF]) participants were measured with a two-alternative forced choice (2AFC) grating orientation identification task and a 10-digit identification task. The CSFs obtained from the two tasks were compared.ResultsThe estimated CSFs from the two tasks matched well after controlling for stimulus types and performance levels. The root mean square error (RMSE) between the CSFs from the two tasks was 0.093 ± 0.029 (300 trials) and 0.131 ± 0.016 (100 trials) log10 units for young and older observers, respectively. To reach the same standard deviation (0.1 log10 units), the digit CSF test required fewer trials/less time than the classic grating CSF for young (60 vs. 90 trials) and older (15 vs. 21 trials) observers. The complicated behavioral responses of the observer in the 10-AFC digit identification task can be accounted by a model that consists of digit similarity and one single parameter of sensory noise (χ2[99] = 3.42, P = 0.999).ConclusionsThe estimated CSFs from the digit test highly matched those obtained from the grating test; however, the digit test is much more efficient.Translational RelevanceThe digit CSF test provides a compatible assessment of the CSF as the traditional grating CSF test with more efficiency.

Aging affects a variety of visual functions. In this study, we aim to quantitatively investigate the temporal characteristics of visual processing in aging. METHODS. Twelve younger (24.1 ± 1.6 years) and 12 older observers (58.4 ± 3.6 years) participated in the study. All participants had normal or corrected-to-normal vision. The contrast thresholds of the participants were measured using an orientation discrimination task with white external noise masks. The target-mask stimulus onset asynchronies were 16.7 ms, 33.4 ms, 50.0 ms, 83.4 ms, and ∞ (no external noise masks) in separate conditions. The signal stimulus was carefully chosen such that it was equally visible for the younger and older participants. An elaborated perceptual template model (ePTM) was fit to the data of each participant. RESULTS. Without masks, there was no difference in contrast thresholds between the younger and older groups (P = 0.707). With masks, contrast thresholds in the older group elevated more than those in the younger group, and the pattern of threshold elevation differed in the two groups. The ePTM fitted the data well, with the older observers having lower template gains than the younger observers (P = 3.58 × 10 −6). A further analysis of the weight parameters of the temporal window revealed that the older observers had a flatter temporal window than the younger observers (P = 0.025). CONCLUSIONS. Age-related temporal processing deficits were found in older observers with normal contrast sensitivity to the signal stimuli. The deficits were accounted for by the inferior temporal processing window of the visual system in aging.