Table 4. Average Effect Sizes (Cohen’s d) for Group Differences in Four Tasks Reported in Ratcliff et al. (2006a) and Three Tasks in Ratcliff et al. (2010).

Parameter	Young adults vs. 60–74 year olds	Young adults vs. 75–90 year olds
Note. Effect sizes for each parameter are averaged across studies, tasks and conditions. Positive effect sizes reflect higher values in older adults.
Drift rate (v)	−.00	−.26
Boundary separation (a)	.98	1.55
Nondecision time (Ter)	1.73	1.81