Why do left-handers earn less than right-handers?

Reaching Out Of MoneyBy Alex Fradera

It’s popularly believed that left-handers are uncommonly blessed with talents like high intelligence or an artistic temperament, but this is a myth. In fact, some studies even show cognitive deficits in lefties (though other research has failed to confirm this) and in terms of their take-home salaries, surveys suggest that left-handers lag behind the right-handed by as much as ten per cent, possibly indicating a difficulty in competing under commercial conditions. In a recent study in PLOS One, Marcello Sartarelli from the Universidad de Alicante attempted to replicate this deficit under controlled laboratory conditions using a simulated labour market. Lefties actually competed more strongly than expected, but they also exhibited some intriguing performance quirks linked with personality that set them apart from the right-handed majority.

Sartarelli recruited 432 people, eight per cent left-handers, to play a game that captured two aspects of labour market success: putting in the appropriate effort and cutting good deals. The game was complex, but boiled down to some participants offering employment contracts to pairs of other participants who played the roles of the “workforce” in the simulation.

Each workforce pair selected the contract that they thought would generate the best outcome for them. Each member of the pair then selected whether they would be a high-effort worker in attempting to fulfil the contract – which would run down their own resources, but hopefully result in higher overall returns – or put less in, and hope their partner would do the work. The combination of a wisely-chosen contract, and the right amount of effort to get it done well, was the key to succeeding and making money.

The researchers also asked the participants to complete a measure of their tendency to think things through rather than jump to conclusions (“the cognitive reflection test”) and unsurprisingly – given that this was a complicated bargaining game – the participants who came out a winner tended to score higher on this measure. Crucially, and contrary to expectations, the lefties scored as highly on this cognitive test as the right-handers and what’s more, they brought home as much bacon in the simulation.

But although overall performance was indistinguishable between left-handers and right-handers, Sartarelli found some intriguing interactions between personality and performance that were unique to the left-handed sample. The data showed them to earn more when more extraverted, and less when more neurotic, whereas the right-handed group – ten times as large, meaning that effects should be easier to detect – showed no such association between personality and earnings. This might suggest that left-handers fall into certain types, some of whom are well-suited to the kinds of decisions found in a labour market, some less so; further work will need to tease out this result. Sartarelli also found that on the whole, left-handers were more agreeable, and left-handed women slightly more extraverted, as compared with right-handers.

Given these results, what are we to make of the real-world finding that left-handed people suffer in earnings? Well, perhaps the less competitive left-handed personality profile – introverted and less emotionally stable – has negative effects that accumulate over the course of a career. Higher agreeableness is associated with lower earnings, so this may play a part. Most intuitively to me, personality differences and other aspects of being left-handed may affect what people look for in a career, and in aggregate draw them away from certain higher-earning professions. On the basis of Sartarelli’s data, any of these avenues of research appear more plausible than the overly simplistic hypothesis that southpaws don’t have what it takes to excel in the marketplace.

Handedness, Earnings, Ability and Personality. Evidence from the Lab

Alex Fradera (@alexfradera) is Contributing Writer at BPS Research Digest