Tonight, on The Newshour, I noticed that while discussing the recent assasination in Lebanon Theodore Kattouf (former ambassador to Syria) shakes his head negatively while speaking. Who he is and what they were discussing really have nothing to do with my question, and is offered as an example of the trait I’m asking about.
I’ve seen quite a lot of people do this, and I always find it to be a little distracting. It seems to me that they’re trying to convince me of something that they’re not sure of themselves. I do usually get used to it shortly, though.
Anyway, does head-shaking while talking mean anything, body language wise? Are the speakers aware that they’re doing it? I’m wondering if maybe it’s an affectation.
It could be an annoying habit, or it could be Parkinson’s (sp?) disease. I’m sure there are other neurological things that could cause something like that too.
I don’t know the quality of the action to which you refer, but to expand on jasonh300’s answer, another fairly common neurological syndrome that might be in play is ET (Essential Tremor).
I have it, and I had a client who has it (we never discussed it, but I recognized it - it is qualitatively unlike Parkinson’s). Unless you knew what you were seeing, I suppose it might have been possible to interpret his subtle sideways back and forth headshake as some Freudian preconscious negative assessment of whatever he was talking about. In fact, that expression of the syndrome, in my experience, has little to do with the subject matter at hand.
But, this is just an Internet message board, and I’m hardly qualified to make a diagnosis. Just another possibility.
Could be any number of tremors or nervous tics. I have mild Tourettes and one of the tics is a sort of intermittent jerky nodding.
Condoleeza Rice does it all the time. But I noticed that when she gave a speech in Europe last week she wasn’t doing it as much; someone must have told her to stop it. I’ve also seen the same headshaking by “spokespeople” on commercials. It seems not to make sense to shake the head negatively when trying to convince someone of a statement, but it seems they do it for emphasis. I’ve also wondered about it… I don’t think it’s because they have a disease.
No, I don’t think it’s Parkinson’s, or anything neurological, either. They stop when not speaking.
If you want to see an example, there’s video of the segment here, but my tired old iMac won’t play it. It was on Tuesday the 15th.
And yes, Ms. Rice does it to. I forgot about her. Quite a lot of people do it.
Let me take another tack and offer this: Some media handlers coach people on effective nonverbal techniques, as much communication happens at the nonverbal level. Naturally, some coaching is done rather poorly, and some pundits develop their own shtick, thinking it’s authoritative when it really distracts and detracts.
BTW, ever notice how the Network news anchors and star reporters put a lot of body English into their delivery? Former NBC anchor Tom Brokaw was such an accomplished wiggler that I sometimes thought he was listening to hip-hop while delivering the evening news. Just like a superstar in classical music, once a broadcaster rises to a certain level of prominence, it’s expected that s/he develop her/his own personalized moves. Stone Phillips is another big wiggler. CNN’s Andrea Koppell wiggles much more than Daddy Koppell.
Yes, I know you’re wondering what the hell I’m talking about, but just start watching these people, my skeptical friends. Brokaw had it down pat. He belongs in the Piggly Wiggly Hall of Fame.
OK, I’ll stop now. 
…and still find it terribly annoying. I initially suspected it was a subliminal “don’t switch the channel” thing and then became more offended because “I’m the one in control of what I choose to watch”. I’m at the point that as soon as I see someone make that gesture, I’ll automatically do the opposite and switch the channel. It is MY choice and I won’t be manipulated into what programming comes into my home.
Who the hell???
Oh, it was me. 
So it’s not like Katharine Hepburn in On Golden Pond? It’s a deliberate movement?
I don’t know – I did ask my doctor about an irritating tremor/spasm in my LH and arm because I was afraid I might be in danger of stroking out in my early 30s, but his explanation was as simple as the following: there are lots of involuntary contractions, which may arise in people of various dispositions and indications, and they can’t all be explained without rigorous testing.
It’s a middle-eastern/Pakistani/Indian thing. It’s just a cultural body language quirk. Check this video out for a good explanation. It seems to be used in cultures where asserting one’s self blatantly can seem offensive or boorish. Think Bill O’Reily at a dinner party. It’s a gesticular equivalent of “No offense, but…” or “just sayin’.”
Wiki.
Zombies move their heads that way too.
Anyway, the gesture of moving one’s head from side to side is an indication of sincerity. It’s not all that uncommon.