Last night Mitt Romney was nervous and Barack Obama looked confident and relaxed. In the first presidential debate, Obama stuttered a little, particularly at the beginning, while last night it was Romney who was slightly faltering in language from time to time.
As Obama was speaking, Romney had to struggle against the tension to venture occasional smiles, while Obama's smiles of indulgent dismissal were relaxed and comfortable.
Part of Romney's problem is that he may have been 'choking'. He smells the presidency and he wants perhaps too much. Choking happens when you really want a reward too much, and your brains' reward network increases its activity, via the chemical messenger dopamine.
Dopamine has a 'Goldilocks zone' - where too little or too much reduces mental agility via its effects on the front part of the brain - the thinking on your feet part. My impression is that in the last debate, Obama was below his Goldilocks zone, while in this debate, the spur of real competition has brought him to the peak of his mental performance.
Mitt Romney, on the other hand, overloaded his frontal lobes with rather too much dopamine and hence reduced his performance. Dean Mobbs and his colleagues in London have shown this type of thing happening in in the brain - 'choking' is real. [i]
It strikes me - this is an impression not a scientific conclusion - that Obama wants to be president less desperately than does Romney. I think that fact made him somewhat flat and unmotivated in the first debate, but the spur of real competition has energized him into the Goldilocks zone and he is functioning at his peak.
Romney wants to be president so badly that it is hurting him, on the other hand. Barack has run once and won once while Mitt has run once in the primaries and lost once. A second defeat for a man who has almost only ever won in his life is a pretty frightening prospect.
So along with the soaring dopamine causing him to fluff some of his lines because of its effects on the frontal lobes, there is also a surge of the stress hormone cortisol in his blood - again, presumed rather than scientifically verified in this case.
Cortisol, like dopamine, can interfere with mental agility, and it also creates the sort of facial tension, slight breathlessness and faintly trembling voice that Mitt Romney showed.
Obama has won this debate hands down, but has it been enough to undo the damage done by his previous debate performance?