Unmasking deceptive responses
Polygraphs are currently the most widely used method of lie detection but City research into involuntary brain activity could lead to new ways of discriminating between honest responses and deception.
When responding to external stimuli, the brain plans several competing actions before selecting a movement. When we engage in deceptive behaviour, the area of our brain that controls movement - the motor cortex - becomes highly active. Because truth is the brain's default mode, if someone claims "I do not use the internet", their brain must first suppress information saying "I do use the internet" before they act.
The research, published in Biological Psychology, showed that motor cortex activity can unmask intentionally hidden information when people engage in deceptive behaviour. Participants lied about their recognition of famous and non-famous faces by twitching their thumb for 'no' or finger for 'yes' while their brains were stimulated to measure competition between motor responses. Researchers demonstrated that brain activity corresponded to the lies they suppressed.
Dr Kielan Yarrow, Director of the Research Methods and Psychology MSc, said: "By demonstrating the presence of a response conflict in deception, my PhD student Aviad Hadar offered a new and original methodology for developing lie-detection techniques whilst shedding light on the dynamics of response competition."