Other work is trying to make traditional polygraphy better by using, for example, algorithms instead of humans to look at what’s coming in on the needle.

The polygrapher, who is only human, can have a positive or negative bias about the subject that will color the interpretation of what’s on the needles, so there is a lot of work to make it objective. Algorithms can do a better job of telling if there is a good physiological response, but it’s still a big leap to telling whether the person is lying. It’s still in the basic research phase and far from being something that I would feel comfortable relying on, especially when it gets into the issue of cross-cultural communications.

And there are other factors that we don’t completely understand. For example, the kind of person you worry about the most is one who has what we call antisocial personality disorder [a person who is indifferent to the needs of others]. Those people seem to have low guilt and anxiety. Do they have the same physiological response as someone who is “normal”? Yes and no. Lying requires a mental workload, which, according to some scientists, drives up the blood pressure and heart rate regardless of your emotional state, and so there may be some similarities and there may not be. Those are questions that require more investigation. So I personally would not put a lot of stock in any of these measures, including polygraphy per se.