By Jamal (Jimmy) Esmaily

Ludwig Maximilian Universität

Humans like money! There is no surprise there. We seek money and try to maximise our earning. This phenomenon has been, experimentally and theoretically, extensively studied for many years and now we have a good understanding of human reward-seeking behaviour and its brain mechanisms. One interesting question addressed in this research is: Do we respond to money unconsciously too? in this post, we look at a creative experiment where Pessiglione and colleagues studied how conscious efforts may be motivated by information that the participants do not have any conscious access to.

In each trial of the experiment (see Figure 1), the participant first saw a noisy sequence of images followed by the appearance of a thermometer on the screen. At this point, the participant squeezed a force grip with their right hand to push the thermometer marker up. The more force they applied, the higher the thermometer marker went. The participant would earn the prize money for the trial if they forced the marker to the top. The amount of this prize varied from trial to trial. The prize was big (1.0 British Pound) in some trials and small (0.01 Pound = 1 Pence) in other trials. The amount of the prize was indicated by a picture of a Pound or Pence coin embedded in the noisy sequence that the participant watched at the beginning of each trial before the thermometer.

In some of the trials, the prize information was clearly visible because the coin was presented on the screen for a long time (that is, 100ms). In these trials, the participants knew consciously how much money they were fighting for. The behavioural results (Figure 2, right panel, blue arrows) showed that here, participants exerted more effort when they knew that a bigger prize was at stake. The brain activity (Figure 2, left panel, blue arrows) showed a similar pattern. None of these findings are surprising.

In some other trials, the coin was very briefly (50ms or 17ms) displayed and quickly masked by noisy images coming before and after it. In these trials, prize information and therefore, the motivation for effort were subconscious. Participants did not consciously know how much money they were fighting for. The most important finding (Figure 2,right panel, green arrows) was that here too, the participants applied more effort when the subconscious information had indicated that the prize would be high. Participants’ effort was guided by the subconscious information. Brain activity (Figure 2, left panel, green arrows) was also higher when subconscious information had promised a bigger prize.

But why do we care about this? What is so important here? These results tell us that our motivations and consciousness are not the same things. They provide clear evidence for the popular belief, perhaps originally proposed by people like Sigmund Freud, that the reason for WHY we do WHAT we do may be hidden from ourselves i.e., our consciousness. In the unconscious trials, sometimes people applied more force and sometimes less. But, they had no conscious idea that these variations were in fact driven by a hidden image of a Pound or Pence coin that they had seen earlier.