Cognitive effort may make rewards more tempting, as seen in studies where mentally fatigued rats consumed more cocaine and humans ate more snacks. This effect seems specific to rewarding stimuli and has implications for addiction management.
Mental fatigue may increase the appeal of rewards, according to a study involving both rats and humans. Cognitive effort has been associated with a tendency to make unhealthy choices, a connection previously attributed to a weakening of willpower or inhibitory control.
Marcello Solinas and colleagues explore the possibility that cognitive effort may also make unhealthy choices more tempting by increasing the perceived reward. Rats who completed a cognitively demanding task self-administered more cocaine than rats who did not complete a cognitively demanding task—or rats who were allowed to rest to 2–4 hours after completing the complex task.
Study on Humans: Cognitive Effort and Increased Snack Consumption
Humans who were given a task that requires significant cognitive effort—suppressing the thought of a white bear while listing other thoughts—ate more potato chips and rated the chips as better-tasting than controls who had not completed an effortful task, suggesting that cognitive effort intensified participants’ hedonic experience of snacking on the salty and fatty snack.
To rule out the possibility that cognitive effort increases the likelihood that humans make extreme judgments in general, a follow-up study using difficult and easy writing tasks found that ratings of chocolate increased after cognitive effort but ratings of the length of a pen or the brightness of a yellow post-it note did not. The authors suggest that this sequence is not a mere byproduct of evolution but could be adaptive in some contexts. According to the authors, the results have implication for the management of addiction and other unhealthy behaviors.
Reference: “Cognitive effort increases the intensity of rewards” by Mejda Wahab, Nicole L Mead, Stevenson Desmercieres, Virginie Lardeux, Emilie Dugast, Roy F Baumeister and Marcello Solinas, 22 October 2024, PNAS Nexus.
DOI: 10.1093/pnasnexus/pgae432
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