Individual Differences in Delay Discounting

Engle, Randall W · 2008 · OpenAlex

DOI: 10.1111/j.1467-9280.2008.02175.x

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Summary

This study investigates the neural and cognitive mechanisms underlying the established negative correlation between intelligence and delay discounting, a behavioral measure of self-control where individuals prefer smaller, immediate rewards over larger, delayed ones. While previous meta-analyses confirmed that higher intelligence is associated with lower delay discounting (better self-control), the specific processes driving this relationship remained unclear. The authors hypothesized that working memory (WM) processes, which are strongly correlated with general intelligence ($g$), might account for this link. The research aimed to identify whether WM explains variance in delay discounting beyond intelligence and to pinpoint the neural substrates, specifically within the prefrontal cortex, that support this relationship. The study involved 103 healthy adults who completed behavioral assessments and functional magnetic resonance imaging (fMRI) scanning. Intelligence ($g$) was operationalized as a composite score derived from four tests measuring fluid and crystallized intelligence. Working memory was assessed using four span tasks and a 3-back task performed during fMRI scanning. Delay discounting was measured using a hypothetical choice task involving monetary rewards with varying amounts and delay periods, quantified by the area under the discounting curve. fMRI data were analyzed to identify regions of interest (ROIs) where neural activity during the 3-back task correlated with WM performance. These ROIs were then tested for correlations with both $g$ and delay discounting, followed by mediation analyses to determine if neural activity in these regions explained the relationship between intelligence and self-control. Behavioral results confirmed that delay discounting was negatively correlated with both $g$ and WM measures. However, regression analyses revealed that WM did not explain any unique variance in delay discounting beyond what was already accounted for by $g$, suggesting that the mechanisms linking WM to delay discounting are shared with those underlying general intelligence. Neuroimaging results identified six ROIs where activity correlated with WM performance. Among these, only the left anterior prefrontal cortex (aPFC; Brodmann’s area 10) showed significant correlations with both $g$ and delay discounting. Mediation analysis demonstrated that neural activity in the left aPFC partially mediated the relationship between $g$ and delay discounting. Specifically, higher activity in this region was associated with better WM performance, higher intelligence, and reduced delay discounting. The findings indicate that the association between intelligence and self-control is partially supported by processes instantiated in the left aPFC. This region is known to support the integration of diverse information and abstract, relational processing. The study concludes that individuals with higher intelligence may exhibit better self-control not merely due to superior memory maintenance, but because they are more effective at integrating complex, abstract information during decision-making. This suggests that the cognitive capacity for integration, rather than WM capacity alone, is a critical factor in resisting immediate gratification in favor of long-term gains.

Key finding

Neural activity in the left anterior prefrontal cortex partially mediates the relationship between intelligence and delay discounting, indicating that integrative cognitive processes in this region contribute to self-control.

Methodology

lab_experiment

Sample size: 103

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• cognitive capacity variation