NOBODY likes to admit an uncomfortable truth about himself, especially when charged issues such as race, sex, age and even supersized waistlines come into play. That makes the task of the behavioural scientist a difficult one. Not only may participants in a study be lying to those running a test, but they may also, fundamentally, be lying to themselves. [...]

In a paper to be published next month in Social Cognition, a group of researchers led by Eugene Caruso of the University of Chicago report their use of a technique called conjoint analysis, which they have adopted from the field of market research and adapted to study implicit biases in more realistic situations. [...]

In their first study, Dr Caruso and his team recruited 101 students and asked them to imagine they were taking part in a team trivia game with a cash prize. Each student was presented with profiles of potential team-mates and asked to rate them on their desirability.

The putative team-mates varied in several ways. Three of these were meant to correlate with success at trivia: educational level, IQ and previous experience with the game. In addition, each profile had a photo which showed whether the team-mate was slim or fat. After rating the profiles, the participants were asked to say how important they thought each attribute was in their decisions. [...]

They would trade 11 IQ points—about 50% of the range of IQs available—for a colleague who was suitably slender. [...]

n a second study the team asked another group, this time of students who were about to graduate, to consider hypothetical job opportunities at consulting firms. [...]

In effect, they were willing to pay a 22% tax on their starting salary to have a male boss. [...]

Scientists have begun to examine how the city affects the brain, and the results are chastening. Just being in an urban environment, they have found, impairs our basic mental processes. After spending a few minutes on a crowded city street, the brain is less able to hold things in memory, and suffers from reduced self-control. While it’s long been recognized that city life is exhausting — that’s why Picasso left Paris — this new research suggests that cities actually dull our thinking, sometimes dramatically so. [...]

One of the main forces at work is a stark lack of nature, which is surprisingly beneficial for the brain. Studies have demonstrated, for instance, that hospital patients recover more quickly when they can see trees from their windows, and that women living in public housing are better able to focus when their apartment overlooks a grassy courtyard. [...]

The reason such seemingly trivial mental tasks leave us depleted is that they exploit one of the crucial weak spots of the brain. A city is so overstuffed with stimuli that we need to constantly redirect our attention so that we aren’t distracted by irrelevant things, like a flashing neon sign or the cellphone conversation of a nearby passenger on the bus. This sort of controlled perception — we are telling the mind what to pay attention to — takes energy and effort. The mind is like a powerful supercomputer, but the act of paying attention consumes much of its processing power.

Natural settings, in contrast, don’t require the same amount of cognitive effort. This idea is known as attention restoration theory, or ART, and it was first developed by Stephen Kaplan, a psychologist at the University of Michigan. While it’s long been known that human attention is a scarce resource — focusing in the morning makes it harder to focus in the afternoon — Kaplan hypothesized that immersion in nature might have a restorative effect.