Feeling the squeeze? Subliminal incentives and their effects on effortful performance on a grip-strength task

The use of incentives can improve performance in almost any domain. Even performance on intelligence tests can improve by a full standard deviation amongst those with low IQ through rewarding performance. However, new research suggests that we need not even be aware of such motivating factors for them to have an effect on behaviour. Pessiglione et al (2007) show that people will exert greater force on a hand-grip to earn a pound rather than to earn a penny when the amount they will be receiving is presented subliminally for 20ms prior to exertion. Participants did not know which coin they had been presented with but behaved as if they were exerting more force in order to receive the larger amount. The authors also identified a specific brain area, the pallidum "as a key node in brain circuitry that enables expected rewards to energize behavior, without the need for the subjects`awareness". This finding ties in well with a previous post on the blog discussing the psychological consequences of being primed with money in terms of inducing people to distance themselves from others. It seems that money can successfully increase motivation at a subconscious level but that its action on fundamental reward circuitry may reduce interpersonal focus. A study which combined subliminal presentation of varying amounts of money with subsequent evaluation of individual performance and spontaneous group interaction would help support this contention.