Sugar, will and cognitive performance

It is a common folk psychology belief that eating or drinking something carbohydrate rich will benefit performance in concentration, study or work. This phenomena was recently examined in a small but well designed study, with similarities to the placebo-balanced design as popularised by researchers like Fabrizio Benedetti.
The explicit hypothesis is that a view that willpower is limited and can be replenished with sugar will be a self fulfilling prophecy, whilst an unlimited model of willpower will lead to neutral responses to sugar.
This study is essentially about placebo effects of sugar, and suggests that our beliefs about energy, willpower and carbohydrates shape our cognitive responses.
The authors make the commendable point that we can be liberated from dependency on health ruining foods and drinks in the hope of performing better.

Key points:

• Existing beliefs that willpower is unlimited correlate with no response to sugar on cognitive tasks
• Actual consumption of sugar has different effects to the taste of sweetness, or the belief it is sugar.
• Beliefs can be modified quickly and exert effects on response to sugar.
• The performance enhancement form glucose is in part due to socially perpetuated beliefs that willpower is limited, deplete-able and replenished with sugar.

Beliefs about willpower determine the impact of glucose on self-control
Veronika Joba,1, Gregory M. Waltonb, Katharina Berneckera, and Carol S. Dweckb,1