People with full-bladder make better liars, new research shows

© Rickey Rogers
There is a connection between humans' ability to tell a lie and their urgent need to urinate, a recent study by US researchers has shown, claiming that those who have to control the bladder perform a deception task better.

"Liars can successfully use covert self-control strategies to facilitate deception," the research which is to be published in the December volume of Consciousness and Cognition Journal, has shown.

To conduct the study which was supported by the California State University, a number of students were asked to first complete a questionnaire on several controversial issues, and then were asked to drink different amounts of water – 700 ml (requiring high-control of the bladder) and 50 ml (low-control) – having been told it was an unrelated task.

Forty-five minutes later the students were asked to do interviews with a panel – instructed to lie about their opinions on the issues that mattered most to them. Third-party observers were assessing the presence of behavioral cues while the respondents lied or told the truth to an interviewer.

READ MORE: Indiana man sentenced to 8 months in prison for teaching polygraph-beating methods

"In the high-control, but not the low-control condition, liars displayed significantly fewer behavioral cues to deception, more behavioral cues signaling truth, and provided longer and more complex accounts than truth-tellers," the research showed, adding that it was much more difficult to detect a liar in a person who has drank a lot of water and urgently needed to go to a toilet. "Observers revealed bias toward perceiving [such] liars as truth-tellers," the study said.

The researchers studied the so-called Inhibitory-Spillover-Effect (ISE) on a deception task, they said, explaining that physical inhibitory control benefited cognitive inhibitory control during deception. In the two simultaneously conducted tasks – both of which required self-control – the effect was experienced, and the need to control urination urgency covertly facilitated control during the need to hide the truth.

Bladder control and other forms of impulse control involve common neural resources, researcher Iris Blandon-Gitlin explained to New Scientist. "They are subjectively different but in the brain they are not. They are not domain-specific. When you activate the inhibitory control network in one domain, the benefits spill over to other tasks," she said.

READ MORE: ‘Pain signature’: Scientists map aching and its intensity in brain

The research was based on results of a previous British study that has suggested that different activities that require self-control are commonly processed in the brain, with mechanisms involving one type of control possibly enhancing such abilities in a different task. A work by Mirjam Tuk of the Imperial College London revealed that people with full bladders could better resist short-term impulses, and made decisions beneficial in the long run.