The TV movie Flight 93, which re-enacted the hijacking of a United Airlines flight on September 11, 2001, was criticized because it “humanized” the hijackers (despite this apparent humanity of their captors, the movie did portray the passengers and crew on that flight fighting back and eventually causing the plane to crash in a sparse Pennsylvania woodland instead of a crowded city). The critics’ argument was simple: why portray the hijackers, clearly bent on destroying as much life as possible, as anything but vile murderers?

The obvious reply: can’t we, as thinking human beings, overcome such depictions and understand that while the individual hijackers may have had human qualities and even doubts about their mission, the attack itself was still reprehensible? Seeing the terrorists express emotion and regret wouldn’t actually cause us to become more agreeable to their goals. Or would it?

A phenomenon called priming has been shown to have a dramatic impact on all sorts of behavior. In most priming experiments, participants are first asked to do an apparently innocuous task designed to introduce a category of interest to the researchers. Then they are asked to do another task, to see if the primed category influences how they perform that task. For example, participants primed on the category “professor” respond more accurately to a general-knowledge quiz than others who are primed on different categories.

But what about when the primed category is one which the respondent emphatically disagrees with? A team led by Kerry Kawakami explored whether priming could affect attitudes which opposed the inclinations of the people being primed. They asked college students to describe a picture of an elderly woman for five minutes — her hobbies, interests, and general character. Then they asked their opinions on issues which young and old people typically disagree: health care, TV nudity, etc. A control group was primed with a picture of a young woman, and another group wasn’t primed at all. In every case, the college students who had been primed with the concept “elderly” expressed more conservative, “older” opinions. Suspecting that the participants might have caught on to their hidden agenda, the experimenters interviewed them to learn if they had adjusted their responses because of the priming; none indicated any awareness of the purpose of the study.

But still, at some level, the participants may have consciously adjusted their responses. So the researchers tried a subliminal method of priming: instead of showing participants photos of the elderly, they had them perform an unrelated task — ostensibly a judgement test which required them to determine if a word flashed on the screen was a real word or a nonsense word. Between trials of this task, random strings of characters were displayed as a buffer. But preceding these random letters for a brief instant (17 milliseconds), words such as “old” and “gray” were displayed. None of the participants indicated they noticed these words at all. Again, compared to an unprimed group, respondents gave opinions that were more conservative. They were primed without even knowing it.

“Elderly,” however, doesn’t have the same negative connotation as other social groups. Perhaps a category with more stigma would not result in priming. In the Netherlands, where this study was conducted, racist “skinheads” are a growing concern — a fringe element of society, to be sure, but instantly recognizeable. The researchers tried priming participants with the same description task as in the initial experiment, but with picture of a skinhead. They were then asked whether they agreed with a variety of statements, including three statements about issues touching on racism, like “I think that minorities ask for too much in their demands for equal rights.” As before, the responses of participants who had seen and described the skinhead picture were skewed in the direction of skinhead ideology: towards racist responses. In a pilot study taken from the same population, when asked on a scale of 1 (very negative) to 9 (very positive) how they would feel if their attitudes were to become more similar to those of skinheads, the average response was 2.21.

Kawakami et al. say these results suggest that people may “socially tune” their attitudes to conform to the social environment. Further, this behavior appears to be automatic: we can’t control it. Over the long term, unchecked, this process becomes a matter of habit. Does this mean we should censor films like Flight 93? I’d argue to the contrary, for then, assuming the Kawakami team’s analysis is correct, we would indeed be subjected to only one viewpoint, and perhaps in time, come to accept it uncritically.

Kawakami, K., Dovidio, J.F., & Dijksterjuis, A. (2003). Effect of social category priming on personal attitudes. Psychological Science, 14(4), 315-319.