Even one pint of beer can make you feel out of control

A recent study showed that drinking only one pint of beer or a large glass of wine is enough to significantly compromise a person's sense of agency, a feeling of being in control of our actions.

This feeling is an important aspect of human social behavior, as it implies knowledge of the consequences of those actions, reported the study published in the Journal of Addiction Biology.

This new study, Effect of alcohol on the sense of agency in healthy humans, is the first to test the effect of alcohol on a sense of agency. The study focused on low doses of alcohol, typically consumed during social drinking, that do not produce a large impairment of behavior. Until now, research has mostly focused on the loss of inhibitory control produced by obvious drunkenness, characterised by impulsivity, aggression, and risky behavior.

Dr Silvana De Pirro, the lead author of the research paper, said: "Our study presents a compelling case that even one pint of beer is enough to significantly compromise a person's sense of agency. This has important implications for the legal and social responsibility of drivers, and begs the question: are current alcohol limits for driving truly safe?"

Explaining how the study was conducted, Dr De Pirro said: "Measuring a person's sense of agency is tricky. When people are explicitly asked to tell how in control they feel, their answers are affected by several cognitive biases, such as poor introspection, the desire to conform to researchers' expectations, or even the inability to understand the question correctly."

Researchers relied therefore on an indirect measure called 'intentional binding', which has been developed to investigate the unconscious mechanisms of 'volition'. When physical stimuli (such as sounds or lights) follow voluntary actions (such as moving a finger or a hand), people judge actions as occurring later and stimuli as occurring earlier than in reality, hence 'binding' the two. The neural mechanisms responsible for this phenomenon are thought to participate in creating a sense of agency.

In the experiments, subjects drank a cocktail containing doses of alcohol proportional to their BMI to produce blood alcohol concentrations within the legal limits for driving in England and Wales. These doses of alcohol, corresponding to one or two pints of beer, produced tighter binding between voluntary actions and sensory stimuli. This suggested that small amounts of alcohol might exaggerate the sense of agency, leading to overconfidence in one's driving ability and to inappropriate, potentially dangerous behavior.