Friday, June 17, 2005

Another Communication Professor

I'm pleased to report that Dr. Sam Bradley successfully defended his dissertation this afternoon. It was a quite enjoyable defense, actually. And the only one I've ever been at that had an audience in attendance. Although most American universities have their dissertation defenses open to the public--I would say that (at least within Communication departments) the only people who are there are the candidate and the committee of professors--it's usually only about five people.

Today, of course, the committee was there:
Annie Lang, the chair
Mike Gasser, the chair from cognitive science (it was actually a dual PhD that Sam received).
Julia Fox
Erik Bucy
and Me.

Well, today there were six other people in the room. A buch of grad students. . .even Sam's wife. Rather than making it uncomfortable, however, I hardly knew they were there. That is, except when Sam would refer to one of them in his answers--likely trying to remind us that there were 'others' in the room in order to keep the professors from getting too nasty. And, of course, it never did. It was a very well done study that utilized a startle response--a physiological response that is hard-wired into the human (and other) cognitive systems to act as a processing interrupt whenever potentially dangerous stuff comes our way. It's created in the lab by playing a short 50 milisecond burst of white noise (100 Hz) through headphones. Trust me this blast is loud and it makes you startle!! The measure is usually done by placing electrodes just below your eye and measuring how large your blink is in response to the startle proble.

Another important concept to understand re: Bradley's dissertation is the orienting response. This is a more common response in the human system, but one we are much less aware of. It's a response that happens whenever something new enters the sesnory field. It's also known as the "what is it" response. I talk about it a little bit in my posting on May 20. Anyway, whenver something new comes into your sensory field, your cognitive system responds in a predictable way--heart rate slows down for about 6 seconds, skin conductance in your palms increase, alpha waves in your brain are supressed--all indicative of cognitive resources being allocated to processing what's just come along. . . remember, it's the "What is it" response.

So, what does this have to do with startles? Turns out that decades ago, physiologists learned that if you do something to make a person have an orienting resonse just prior to sending that startle probe of white noise. . .the blinks that result will be substantially reduced. This orienting just prior to the startle probe is called a 'pre-pulse.'

Now, what Sam did was take past research that has show that cuts (changes from one scene to another) in television messages cause an orienting response in viewers and draw the logical inference that they woudl therefore act as a a pre-pulse for startle probes he sent to the viewer while they watched. He predicted that this prepulse would cause inhibition of the startle response while viewers watched episodes of ER.. ..turns out that they don't. And, in fact, they cause the startle to increase. Exactly the opposite from what happens in startle research that uses 6 second exposures to emotional still pictures.

I'm certainly not doing the study much justice writing about it at 10:30 at night. And I'd encourage you to contact Sam

1 comment:

Sam said...

If I recall correctly, Rob had his back to the audience. I was just trying to keep them awake by mentioning them every 20 minutes or so.