Expertinent is a regular Stumper column featuring interviews with experts on the news of the day. 

Have you seen an attack ad recently that made you want to vomit? Run away from your television? Turns out those are perfectly natural responses.According to a recent study in the Journal of Advertising, negative campaign ads actually cause physical repulsion in viewers. But here’s what’s even more interesting: the same study found that a viewer's (ahem) uncomfortable gut reaction isn’t bad news for the politician who's trying to win his or her vote. Negative ads tend to induce a stronger emotional reaction--so they leave a longer impression on whoever sees them.

Here’s how the experiment worked: participants watched 30-second Bush and Gore ads from the 2000 campaign with electrodes under their eyes. Those electrodes detected a “startle response”--basically a hard blink, which is indicative of a larger reflexive desire to move away from an unpleasant situation--much more frequently during negative ads than during positive or neutral ones. You might not notice while vegging on the couch, but negative ads actually activate the initial steps of darting away from danger.

Given the stark divergence in the campaigns’ use of negative ads, the research (which was first published in the winter of 2007) feels particularly pertinent now. According to the Wisconsin Advertising Project at the University of Wisconsin, nearly 100 percent of McCain’s Sept. 28 to Oct. 4 spots were negative, compared to 34 percent of Obama’s. “In an ideal world it would be awesome to just run positive ads," says James Angelini, a communications professor at the University of Delaware and one of the study's authors. "But that might not be the best way to get the attention of some undecided voters." The real difficulty, he says, is creating negative ads that are remembered for what they say about the opponent--not for causing a gut-wrenching reaction among viewers. NEWSWEEK’s Sarah Kliff caught up with Angelini to talk about the biology of negative advertising. Excerpts:

So tell me a bit about what’s going on when we view negative political advertising?
What this boils down to is when we are exposed to any sort of negative stimuli, even think back to ancient man having a tiger come into view, a system gets activated that makes you want to avoid it in order to preserve yourself. Nowadays a tiger isn’t going to walk into our line of sight but negative stimuli, even on the TV, activates that same system. It’s so negative, it makes us feel disgust, and we want to flight.

What exactly is similar about being frightened by a tiger and seeing McCain attack Obama?
It’s a biological thing within us. We want to avoid anything negative, be it some sort of physical harm us or something that just make us feel uncomfortable. We want to avoid any sort of negative emotion and that’s what they do, still invoke negative emotions and activate this cognitive system.

And you found that, as creating memorable advertising goes, this isn’t necessarily a bad thing?
When exposed to a negative thing you want to avoid, you have to pay close attention to it. If you go back to the biology of it, and the idea of watching out for lions, you have to pay close attention for survival. When something elicits such strong emotional reactions, you end up paying attention to it. That helps you remember it later because the content is stored.  

So negative ads are more memorable. Is there a positive way to make political ads memorable? You write that the equivalent, in beer advertising, is “scantily clad models” because they elicit a strong emotional response.
Evolutionarily, our main goal is to eat, and to reproduce. Exposure to something like models, for a certain demographic, can elicit a strong, positive emotional response. I really am not sure if there’s an equivalent in campaign advertising. You can’t have Obama and McCain surrounded by scantily clad women. It’s hard to make the same connection [you can with negative advertising] with a positive ad.

Does that mean negative advertising is the way to go?
Not necessarily. People might remember it more, but how are they going to remember it? Are they remembering this candidate putting out this negative ad, and making them uncomfortable, or are they remembering the attacks launched on the opponent? It’s a fine line. You don’t want to go too negative, and produce that gut reaction against your candidate, but also being negative is going to help you be more memorable. 

Is there any research on the reaction to negative ads that looks at the partisan divide--like how you react to a negative ad by the candidate you support versus their opponent?
We measured that in our participants, how they felt about Bush and how they felt about Gore, and there wasn’t a significant difference in how much they startled.

If Obama or McCain read your study, what should they take away from it?
If Obama and McCain were to run a long series of positive ads, it might not be the best thing. They wouldn’t be that memorable and would probably impact the people who are already voting for them. You have to be aware of the few undecideds and what kind of impression you’re leaving them with. If you attack to hard, they might avoid voting for you because of that natural startle reaction. But if you don’t attack at all they forget your ad. In an ideal world it would be awesome to just run positive ads, but that might not be the best thing to get the attention of some undecided voters.