Scientists have shed new light on the challenges facing exercise professionals in getting the population moving, after new research has found that obesity causes people to see distances as farther and hills steeper than they actually are.

The findings of the study – which was published in the journal Acta Psychologica* in March 2016 – paint the picture of a vicious circle, whereby various types of exercise are perceived to be more challenging as a person’s weight increases.

Points of view
For the study, three researchers – two from Colorado State University and one from Purdue University, US – carried out tests on 66 random volunteers.

In one experiment, the people were asked to judge the distance of a cone that was located 25m away. The researchers found that a 21-stone person saw the distance as 30m, while a 9-stone person saw that same distance as 15m.

In another test, people were asked how steep they thought a nearby hill was. The heavier people thought the incline was greater than their slimmer counterparts – which may be one explanation as to why heavier people are often more likely to take a lift rather than the stairs.

“You’re not seeing the world as it is – you’re seeing the world in terms of your ability to act,” says Dr Jessica Witt, a psychologist at Colorado State University who presented the findings at the American Association for the Advancement of Science in February.

Perceptual bias
“We think these perceptual biases can create a vicious circle for people with obesity. It is conscious perception of the world,” adds Witt. “But it’s not based on conscious perception of the body or feelings of laziness.”

The phenomenon is thought to stem from a survival mechanism in early humans, designed to quickly evaluate our ability to tackle testing situations. However, the reflex appears to be counter-productive in persuading overweight people to be more active.

The researchers suggest setting easier targets for obese people who are starting out on exercise regimes, to avoid early discouragement. Using telescopic glasses to change distance perceptions was also mooted.

*Witt, J et al. Perceived distance and obesity: It’s what you weigh, not what you think. Acta Psychologica. Volume 165. March 2016