A team from Newcastle University found people put nearly three times as much money into an 'honesty box' when they were being watched by a pair of eyes on a poster, compared with a poster that featured an image of flowers.
The researchers say the eye pictures were probably influential because the brain naturally reacts to images of faces and eyes. It seems people were subconsciously cooperating with the honesty box when it featured pictures of eyes rather than flowers.
They also say the findings show how people behave differently when they believe they are being watched because they are worried what others will think of them. Being seen to co-operate is a good long-term strategy for individuals because it is likely to mean others will return the gesture when needed.
Details of the experiment, believed to be the first to test how cues of being watched affect people's tendency for social co-operation in a real-life setting, are published today, Wednesday June 28, in the Royal Society journal Biology Letters.
An honesty box is a system of payment which relies on people's honesty to pay a specified price for goods or services - there is no cashier to check whether they are doing so.
For this experiment, lead researcher Dr Melissa Bateson and her colleagues Drs Daniel Nettle and Gilbert Roberts, of the Evolution and Behaviour Research Group in the School of Biology and Psychology at Newcastle University, made use of a long-running 'honesty box' arrangement.
This had been operating as a way of paying for hot drinks in a common room used by around 48 staff for many years, so users had no reason to suspect an experiment was taking place.
An A5 poster was placed above the honesty box, listing prices of tea, coffee and milk. The poster also featured an image
Contact: Dr. Melissa Bateson
University of Newcastle upon Tyne