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Francesca Fortenbaugh, Alexander Sugarman, Julia Brau, Joseph DeGutis, Laura Germine, Michael Esterman; Web-Based Assessment of Visuospatial Processing Speed Across the Lifespan. Journal of Vision 2021;21(9):2768. doi: https://doi.org/10.1167/jov.21.9.2768.
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© ARVO (1962-2015); The Authors (2016-present)
While declines in visuospatial processing speed in adults over 65 years are well documented, more fine-grained lifespan changes are not well characterized. Here we developed a novel visuospatial processing speed task for web-based platforms adapted from the Useful Field of View paradigm. This dual task required both discriminating a tumbling E’s orientation at fixation and localizing a blue diamond among a peripheral ring of distractors (conjunction search) on each trial. An adaptive bestPEST threshold estimation was implemented to determine stimulus duration thresholds in 50 trials. Data was collected from 4,718 volunteers between 12-62 years old (55% male) on TestMyBrain.org. Binned average thresholds as a function of age were calculated using a 3-year sliding window. The average thresholds were well modeled by a segmented linear function with peak performance occurring at 22 years (95%CI: 19-28) and increasing by approximately 9ms/year afterward. This is reflected in the observed doubling of threshold durations across 20 vs. 60-year-old participants (412ms vs. 817ms). As this task assumes fixed slope and lapse rate parameters for the Weibull function used in the bestPEST algorithm, a simulation study was also completed to assess how deviations in these parameters from an individual’s best-fitting parameters impact the stability of threshold results. Over 7 million simulations were completed varying combinations of threshold, slope, and lapse rate parameters to determine the probability of a correct response when the bestPEST was run using the fixed slope and lapse rate. Results show strong correlations between true and estimated thresholds for all slope/lapse rate combinations (r = 0.84-0.99). Comparisons across pairs of thresholds show that ordinal rankings for threshold differences >20% were preserved over 90% of the time. These simulation results validate that the slowing observed in our online data reflects age-related declines in processing speed and use of adaptive algorithms for web-based testing platforms.
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