Figure 3.

Linear mixed-effects model fit for median interkey delay (model 1, sample A in Table 2) as a function of age and time of day. A nonlinear diurnal pattern for typing speed was found, with the fastest typing occurring midday (12 pm to 3 pm) and the slowest typing at night. Older users are also shown to exhibit slower typing. Last, the significant interaction between age and time of day results in a more pronounced slowing in older users in the evening. Model obtained by plotting median interkey delay at different times in the day while fixing all other model covariates at their average value. The shaded area represents standard error ribbons.