It also illustrates the complexity of teasing apart motivation. He believes the giant potential rewards on offer to some of his Indian subjects undermined their ability to perform by making them overly focused or mentally aroused. This idea that there is an optimal level of mental arousal that stimulates good performance, which when either lowered or raised undermines our abilities, was first proposed by US psychologists a century ago.
This concept of failure to perform under pressure, or "choking", is well known in sport. A famous example saw French golfer Jean Van de Velde needing to sink the ball in six shots on the last hole of the final round of the 1999 British Open to win. Having done so in just three shots in the two previous rounds, he crumbled under pressure and took seven shots, before losing the resulting play off.
Jump for cash
A key problem that has faced those in this field in the past has been the difficulty of measuring motivation using psychological tests and questionnaires. But the increasing use of brain imaging technologies in neuroscience has provided a new and more direct method to study thoughts and feelings. These techniques are now being adopted to tease apart the different aspects of motivation.
Dean Mobbs, of the University of Cambridge, UK, and colleagues, for example, have used brain scanning to show how choking is manifested in the brain. In his study participants played a computer game in which they had to race against the clock to catch a prey in a simple, two-dimensional maze, while their brains were scanned by an MRI machine. They were told they would win either 50p or £5 if they succeeded within the time limit.
The results, published in the journal Psychological Sciences in 2009, showed performance was worse when the larger bonus was on offer and that this was associated with increased activity in brain regions involved in motivation. Mobbs suggests that excessive activity in areas of the brain that deal with motivation can come to dominate our decision-making abilities, leading us to make more mistakes, or "choke on the money".
In his experiments in India, Ariely expected, based on previous work, that large rewards would undermine performance in tests of motor skills and creativity but not those involving memory. In fact they led to worse results in all three. He believes this was down to the huge size of the payments causing his participants to choke. So to try to work out what types of tasks could be motivated by money he set up a second experiment in which he offered two groups of American students rewards of $15 to $30, or $150 to $300, if they did well in tasks involving maths or repetitive key-pressing. In the key-pressing task participants earned an average of 78% of maximum potential earnings when offered the larger incentives versus 40% for those receiving the smaller sums. In contrast, in the maths tests, the larger payments undermined performance, with recipients earning only 43% of their maximum potential earnings, compared to 63% when offered lower financial rewards.
“If I gave you a bigger bonus to jump you would jump more times," says Ariely. "You have very good control over your legs and if I give you more money you will transmit more power to them and therefore you will be more successful. We don’t have the same control over memory, creativity and concentration. You can’t will yourself into a higher state of concentration and creativity. It’s actually counterproductive and hinders performance strongly.” Anyone that has tried to force themselves to concentrate can probably relate to those findings. But there are also more subtle effects of motivation that can be teased apart using these new techniques.