Biasing Context
and Demand Characteristics

People who participate in research can be influenced by many biasing factors. These include the overall context of a poll or experiment (who is conducting it, where it is conducted, how it is conducted) as well as comments made to people and even objects in the room where the experiment takes place.

How can a biasing context be setup before data collection begins?

A biasing context may be set up before a poll is ever started. If a telephone pollster starts by saying, "Hello, I'm calling from Fox News…" he or she will elicit different responses from a pollster who starts by saying, "Hello, I'm calling from CBS News." The same thing could happen in almost any country; just pick one network that typically supports the current government and one network that typically opposes. People do not have to be told how to respond; they know. They may rebel and give "wrong" answers, but they usually think they know what the pollster would like to hear.

Biasing effects can also be created beforehand by the pollster's organization such as a government, company, or university. The makers of Tylenol created a useful biasing context in the late 20th Century by giving free samples of their products—lots of free samples—to hospitals all over the United States. Patients in hospital did not have to pay for non-prescription pain relievers; they received free samples of Tylenol. Then the makers of Tylenol ran a television ad campaign pointing out, with complete honesty, that Tylenol was used more often than any other pain medication in hospitals all over the country.

The U.S. government, in 2005, had their Drug Czar visit Canada to plea for help in controlling marijuana. Canadians asked the Drug Czar skeptical questions about the dangers of marijuana. The Drug Czar replied that more people in the U.S. were receiving treatment for marijuana than for any other drug. This was true. The implication was that large numbers of people felt they needed help quitting a dangerous drug. The Drug Czar neglected to mention that people arrested for possession of marijuana in the U.S. were generally given two options: going to jail or attending a treatment course. He knew this, but it served his purpose better to cite the statistics about people in treatment without discussing the biasing context.

What are demand characteristics?

Martin Orne is a psychologist who recognized in the early 1960s that all data collection situations create implicit (unspoken) demands on the people who contribute data, and this may have a big effect on results. Orne coined the term demand characteristics to label such influences. Typically the pressure is not overt. No researcher is likely to say, "Respond this way, because this is what I expect." But people in an experiment often wish to please the researcher, so they try to figure out how they are "supposed" to respond (even if the researcher has no such agenda).

Demand characteristics may explain why educational researchers looking for new, effective teaching techniques often produce positive results. This fact was mentioned earlier in the section titled The Importance of Replication. Enthusiasm or positive expectations of the original researchers may be conveyed to the people in their study, who try hard to produce positive results. If the research is replicated by somebody who is skeptical, the effect may disappear, because the demand characteristics are absent or reversed.

The opposite of demand characteristics can occur when subjects resent being included in research and try to sabotage it. This is a problem at some colleges and universities where introductory students must participate in a subject pool, serving as volunteers, whether or not they they want to. Some students produce deliberately absurd data, such as marking all their answers the same way. When I was in graduate school this was called the "F--- You" effect.

How did a young experimenter create a biasing context?

Demand characteristics can involve any information that biases a person's response to research. Once a 14 year old student wrote to me asking for help with a science fair project. She wanted to test the ability of fellow students to detect and discriminate odors. I suggested that she explore the effects of demand characteristics by having people sit down in front of a table with fragrant objects like fruit and perfume bottles, then (after they put on a blindfold) asking them to identify completely different things that were not on the table. The student wrote back a month later and said the experiment produced interesting results. People's answers depended more on what they saw on the table before the experiment than on what they actually sniffed during the experiment, even though the student said nothing to them about the objects on the table.

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Copyright © 2007 Russ Dewey