The effects of aging on simple 2-choice decision making was investigated with the diffusion model (R. Ratcliff, 1978). Data for 75- to 90-year-olds were collected and compared with previous data from 60- to 75-year-olds and college students for 5 tasks: a signal detection-like task, letter and brightness discrimination with masking, recognition memory, and lexical decision. The model fit the data well and therefore allows components of processing to be examined as a function of age. Compared with decision-making processes in college students, decision criteria and nondecision components of processing increased with participants' age. However, the quality of the evidence on which decisions were based decreased with age only for letter and brightness discrimination.
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