The Temporal Window of Visual Processing in Aging

Abstract

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.

Defective Temporal Window of the Foveal Visual Processing in High Myopia

“…For more details about the ePTM, please see Appendix A and elsewhere. 29,37 In the analysis, data from two participants, one in the LM group and the other in the HM group, were excluded because their peak and full width at half maximum (FWHM) of the temporal profile exceeded ±2 SDs of the range about the mean. The data of the remaining 34 participants are presented in this article.…”

“…This paradigm has been previously used to investigate the temporal profile under the effects of attention 28 and aging. 29 Both central (0°) and more peripheral (7°) visual fields were examined in low and high myopia. The contrast threshold in the condition without noise masks was used as the baseline performance for spatial vision.…”

Temporal Characteristics of Visual Processing in Amblyopia

“…The two eyes of amblyopic patients were measured separately. Because no significant difference between the two eyes of normal observers was found in our previous study ( He et al, 2020 ), only the dominant eye of the normal observer was tested. Each observer was given a practice session of about 75 trials before the experiment started.…”

“…The remaining frames in the 17-frame sequence other than those of signal or external noise were filled with blank frames with background luminance. The same temporal configurations were also used in Lu et al (2004) and He et al (2020) .…”

“…The original PTM has been applied in studying the spatial template in amblyopia ( Xu et al, 2006 ). The elaborated PTM (ePTM) with additional parameters describing the temporal profile of visual processing has been used to study effect of attention ( Lu et al, 2004 ) and aging ( He et al, 2020 ). Here, we adopted the ePTM ( Lu and Dosher, 1999 , 2008 ; Lu et al, 2004 ; Hou et al, 2014 ) to fit the trial-by-trial response data for each observer.…”