“Mental Speed Is High Until Age 60 As Revealed by Analysis of over a Million Participants”, 2022-02-17 ():
Response speeds in simple decision-making tasks begin to decline from early and middle adulthood. However, response times are not pure measures of mental speed but instead represent the sum of multiple processes.
Here we apply a Bayesian drift-diffusion model to extract interpretable cognitive components from raw response time data. We apply our model to cross-sectional data from 1.2 million participants to examine age differences in cognitive parameters. To efficiently parse this large dataset, we apply a Bayesian inference method for efficient parameter estimation using specialized neural networks.
Our results indicate that response time slowing begins as early as age 20, but this slowing was attributable to increases in decision caution and to slower non-decisional processes, rather than to differences in mental speed. Slowing of mental speed was observed only after ~age 60.
Our research thus challenges widespread beliefs about the relationship between age and mental speed.
…Mental speed: Drift rates—that is, our proxy for measuring mental speed—increase notably from age 10 to 30 in our cross-sectional data (̄b = 0.034 until the first change point; 95% HDI, (0.033, 0.034)). After this, the mean values of drift rates remain fairly stable until age 60, showing little age-related difference during middle adulthood (|̄b| < 0.001; 95% HDI, (−0.001, 0.000)). Around age 60, an accelerated negative trend in mental speed commences, which holds until age 80 (̄b = −0.020; 95% HDI, (−0.021, −0.018)). Importantly, this inverted U-shaped pattern does not mirror the age patterns found for the other DM parameters and mean RTs. Our change points are estimated at ages 24 (posterior mean, 24.4; 95% HDI, (22.8, 26.2)) and 60 (posterior mean, 59.9; 95% HDI, (56.9, 62.8)).