I thought this theory was a bit ridiculous when I read it - until I put it to the Clinton test. The theory comes from recent study, reported in the Telegraph, that found that people blink much more rapidly after telling a lie. This from the Telegraph:
Liars blink less frequently than normal during the lie, and then speed up to around eight times faster than usual afterwards.
The findings, reported in the Journal of Non-verbal Behaviour, means that blink rates could soon be used by professionals, such as the police and security forces, to tell when someone is being duplicitous.
Dr Sharon Leal, co-author of the study at Portsmouth University, said: "It is striking what different patterns in eye blinks emerged for liars and truth tellers.
"Such striking differences in behaviour between liars and truth tellers are rarely seen in deception research."
. . . Results show that when the questions were being asked and the answers given, the blink rate in the liars went down. In contrast the truthful group's rate went up, though this could have been down to test anxiety.
Afterwards, the blink rate of the liars increased rapidly, while that of the truth tellers remained the same.
Researchers believe the increased effort involved in telling fibs could be the reason why liars do not blink during the act of lying.
Dr Leal said: "Liars must need to make up their stories and must monitor their fabrication so that they are plausible and adhere to everything the observer knows or might find out.
"In addition, liars must remember their earlier statements, so that they appear consistent when re-telling their story, and know what they told to whom. Liars will be more inclined than truth tellers to monitor and control their demeanour so they will appear honest.
"The reasons why there is a flurry of blinks after the lie is not really clear. It may be that this flurry is a kind of safety valve, like a release of energy after the tension of lying."
Now with that in mind, take a look at probably the most famous lie of the last two decades in American politics, Bill Clinton's "I did not have sexual relations with that woman" speech. The speech comes in the last 40 seconds of the video below, but it pays to watch a lot of the lead up to get a feel for Clinton's normal blink pattern. He blinks fairly rarely. When he starts into his lie, his eyes stay open for a bit, but then he begins blinking with much greater rapidity as he continues with the lie.
Obama I am unsure of. He either has a naturally fast blink pattern or he is lying his veritable ass off in this response wherein he says that people are lying about his record on abortion.