Humans are hard-wired to follow the path of least resistance

The amount of effort required to do something influences what we think we see, finds a new UCL study suggesting we're biased towards perceiving anything challenging to be less appealing. 'Our brain tricks us into believing the low-hanging fruit really is the ripest,' says Dr Nobuhiro Hagura, who led the UCL team before moving to NICT in Japan. 'We found that not only does the cost to act influence people's behaviour, but it even changes what we think we see.' For the study, published in eLife , a total of 52 participants took part in a series of tests where they had to judge whether a cloud of dots on a screen was moving to the left or to the right. They expressed their decisions by moving a handle held in the left or right hand respectively. When the researchers gradually added a load to one of the handles, making it more difficult to move, the volunteers' judgements about what they saw became biased, and they started to avoid the effortful response. If weight was added to the left handle, participants were more likely to judge the dots to be moving rightwards as that decision was slightly easier for them to express. Crucially, the participants did not become aware of the increasing load on the handle: their motor system automatically adapted, triggering a change in their perception.