People often make decisions involving trade-offs between smaller immediate and larger delayed rewards. In intertemporal choices such as these, individuals tend to discount the value of future rewards, a tendency known as temporal discounting. Most people exhibit some degree of temporal discounting, but the rate at which people discount future rewards varies widely. Two neurocognitive systems have been proposed as potential candidates for mediating individual differences in discounting: executive function and declarative memory. Both of these functions decline as people age, at rates that vary across individuals. Here we leverage this variability in cognitive abilities among older adults (both cognitively normal and with mild cognitive impairment, MCI) to investigate associations between temporal discounting and executive function versus declarative memory. We find that neuropsychological measures of declarative memory (episodic memory retrieval and semantic fluency), but not executive function (Trail Making Test and lexical fluency), are associated with temporal discounting. People with better memory discount delayed rewards less. Consistent with this, individuals diagnosed with MCI show steeper discount rates compared to cognitively normal older adults. In contrast, executive function, but not declarative memory, is associated with the extent to which an individual is risk-neutral, or expected-value maximizing, in a risky choice task. These findings elucidate the inconsistent literature on aging and economic preferences, and they suggest that distinct neural systems mediate individual differences in the risk and time domain.
Measuring self-efficacy, executive function, and temporal discounting in Kenya
