Summary: New research reveals that mental fatigue makes rewards like unhealthy snacks more tempting. Both rats and humans who exerted cognitive effort sought out more rewards, with rats self-administering more cocaine and humans rating snacks as tastier.
This suggests that cognitive fatigue intensifies the desire for rewards, rather than simply weakening willpower. The findings offer insights into managing addiction and unhealthy behaviors, showing how mental effort can influence decision-making.
Key Facts:
- Cognitive effort increases the perceived desirability of rewards.
- Rats and humans both sought more rewards after completing difficult tasks.
- The study provides insights into managing addiction and unhealthy habits.
Source: PNAS Nexus
Mental fatigue may make rewards more desirable, according to a study in rats and humans.
Exerting cognitive effort has been linked with making unhealthy choices. In the past, the link has been explained via a weaking of inhibitory control or will power.
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 cognitive demanding task—or rats who were allowed to rest to 2–4 hours after completing the complex task.
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.
About this behavioral neuroscience research news
Author: Marcello Solinas
Source: PNAS Nexus
Contact: Marcello Solinas – PNAS Nexus
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Cognitive effort increases the intensity of rewards” by Marcello Solinas et al. PNAS Nexus
Abstract
Cognitive effort increases the intensity of rewards
An important body of literature suggests that exerting intense cognitive effort causes mental fatigue and can lead to unhealthy behaviors such as indulging in high-calorie food and taking drugs.
Whereas this effect has been mostly explained in terms of weakening cognitive control, cognitive effort may also bias behavioral choices by amplifying the hedonic and emotional impact of rewards.
We report parallel findings with animals and humans supporting this hypothesis. In rats, exerting cognitive effort immediately before access to cocaine self-administration significantly increased drug intake. In addition, exerting cognitive effort increased the psychostimulant effect of cocaine.
The effects of cognitive effort on addiction-related behaviors were eliminated and even reversed when animals could rest in their home-cage for 2–4 h before access to cocaine self-administration.
Among humans, we found that expending cognitive effort increased consumption of tasty (but unhealthy) food by increasing the hedonic enjoyment of consuming the food. In addition, the effects were specific for emotionally relevant stimuli (i.e. food rewards) and did not generalize to judgment about neutral objects.
Altogether these data suggest that intense cognitive effort can increase the perceived intensity of rewards and lead to their overconsumption.
This effect may contribute to bad decision making induced by excessive cognitive effort and make people more vulnerable to indulge in unhealthy behaviors such as use of addictive drugs.
