Navigation Links
University of Pennsylvania: Contrary to popular models, sugar is not burned by self-control tasks
Date:6/11/2010

PHILADELPHIA - Contradicting a popular model of self-control, a University of Pennsylvania psychologist says the data from a 2007 study argues against the idea that glucose is the resource used to manage self control and that humans rely on this energy source for will power.

The analysis, conducted by Robert Kurzban and published in the current issue of the journal Evolutionary Psychology, shows that evidence previously presented in favor of the claim that the brain consumes extra glucose when people exert self-control shows no such thing.

The new analysis contradicts results published in the Journal of Personality and Social Psychology based on "resource" models of self control, suggesting that when people exert self control -- by, for example, carefully focusing their attention -- a resource is "depleted," leaving less of it for subsequent acts of self control. This study identified glucose as this resource that gets depleted.

"For this model to be correct, it obviously must be the case that performing a self-control task reduces glucose levels relative to pre-task levels," Kurzban said. "Evidence from neurophysiology research suggests that this is unlikely, and the evidence for it is mixed at best."

By analyzing the portion of the data made available by prior researchers, Kurzban discovered that, in the studies reported, glucose levels did not decrease among subjects who had performed self-control tasks. In short, his reanalysis shows that the researchers' own data undermine the model they advance in their paper.

Kurzban's new analysis is consistent with the neuroscience literature, which strongly implies that the marginal difference in glucose consumption by the brain from five minutes of performing a "self-control" task is unlikely in the extreme to be of any significant size. Further, research on exercise shows that burning calories through physical activity, which really does consume substantial amounts of glucose, in fact shows the reverse pattern from what the model would predict: People who have recently exercised and burned glucose are better, not worse, on the sorts of tasks used in the self-control literature.

"The failure to find the effect predicted by the glucose model of self control is not surprising given what is known about brain metabolism," Kurzban said. "Even very different computational tasks result in very similar glucose consumption by the brain, which tends to metabolize glucose at similar rates independent of task."

Furthermore, even if exerting self control did reduce levels of glucose, the cause of the reduction could be factors such as increased heart rate when people perform certain kinds of tasks, rather than consumption by the brain. Glucose levels are probably influenced, Kurzban said, by a cascade of physical and psychological mechanisms that mediate glucose levels throughout the body.

"The weight of evidence implies that the glucose model of self control in particular - and perhaps the resource model in general - ought to be carefully rethought," he said. "From a computational perspective, a 'resource' account is the wrong kind of explanation for performance decrements to begin with. No one whose computer is performing slowly would think that the fault lies in not having sufficient electricity - or that running Excel for five minutes will drain the battery and so make Word slow down - even though no one would deny that electricity is necessary for computers."

One way to put the prior data in context, according to Kurzban, is to consider the data in terms of the familiar unit of calories. The brain as a whole consumes about one quarter of one calorie per minute. Obviously, the consumption rate for just the fraction of the brain involved in "self control" must, logically, be much smaller than .25 calories per minute. A 1 percent increase across the entire brain would, over the course of a five-minute task, consume .0125 calories. If one assumes an order of magnitude greater effect, a 10-percent increase, the amount of energy consumed would still be much less than a single calorie.

"Even with these extreme assumptions, potentially off by orders of magnitude, the caloric cost would still be well less than .2 calories," Kurzban said. "The brains of subjects categorized as 'depleted' in this literature, have, relative to controls, used an additional amount of glucose equal to about 10 percent of a single Tic Tac."


'/>"/>

Contact: Jordan Reese
jreese@upenn.edu
215-573-6604
University of Pennsylvania
Source:Eurekalert

Related medicine news :

1. Bridgepoint Educations University of the Rockies Introduces New Master of Arts Specialization in Career Management and Counseling
2. University of Maryland chemist receives Astellas Award for blindness prevention research
3. Morehead Presents Webinar on “Building Employee Engagement in a University Healthcare Environment”
4. Oakland University William Beaumont School of Medicine Reaches Development Milestone
5. Women should be allowed to eat, drink during labor: Queens University researcher
6. University of Alberta researchers develop drug interface to save lives
7. University of Utah Announces New Studies on the Benefits of Treadmill Desks
8. St. Jude and Washington University team to unravel genetic basis of childhood cancers
9. Childhood Apraxia of Speech Association of North America Awards Treatment Research Grant to University of New Mexico/PROMPT Institute
10. Disease of Poverty: University of South Carolina Releases Journal on Cervical Cancer, Health Disparities
11. University of Michigan Health System Receives $15 Million Gift, The Largest Ever for Womens Health
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:8/19/2017)... Calif. (PRWEB) , ... August 18, 2017 , ... Western ... in health and education to launch the University’s new Center for Innovation on Wednesday, ... WesternU Health Education Center Lecture Hall 1, followed by a technology exhibition from 1 ...
(Date:8/19/2017)... ... August 19, 2017 , ... Curl Keeper® is excited to ... Curl Leaders, Editors’ Choice 2017 Award for the second year in a row. The ... and curlies alike was voted Best Moisturizer for Type 2 Wavies and Best Refresher ...
(Date:8/19/2017)... ... August 19, 2017 , ... ... joined its Orlando location as an interventional pain management physician. He brings a ... the treatment of migraine headaches, and significant experience in spinal cord stimulation for ...
(Date:8/18/2017)... , ... ... ... For Immediate Release                Contact: ... Shows Young Women Seek Sex and Relationship Advice from their ...
(Date:8/18/2017)... ... 18, 2017 , ... Mediaplanet today announces the launch of ... and highlighting the importance of proactive eye and ear health. The campaign focuses ... innovations in hearing aid technology. , In this issue, the American Speech-Language-Hearing ...
Breaking Medicine News(10 mins):
(Date:8/15/2017)... Aug. 15, 2017   Mostyn Law and Gulf Coast ... Houston, Texas . The Mostyn Law family has ... years. That is why Mostyn Law is partnering with ... to show its appreciation. Blood supplies are running low. ... short of hospital needs in August. That is why the blood ...
(Date:8/14/2017)... and PETACH TIKVAH, Israel , Aug. ... a leading developer of adult stem cell technologies for ... ending June 30, 2017. ... for our pivotal Phase 3 trial to investigate NurOwn ... President and Chief Executive Officer of BrainStorm. "We have ...
(Date:8/7/2017)... Md. , Aug. 7, 2017 ... healthcare member acquisition, retention, and engagement, announced the ... of Strategy and Product Development, effective as of ... consulting and technology implementation strategy for our clients. ... of experience in consulting and business analytics within ...
Breaking Medicine Technology: