Demand characteristics refer to the subtle cues or signals that inform participants in a study about the researcher’s expectations. These cues can influence participants’ behaviour, thereby affecting the validity of the study’s results. The term was first coined by psychologist Martin Orne in the 1960s to describe how the experimental context can impact a participant’s actions.

Examples that illustrate the concept

Imagine you’re participating in a study about memory retention. If the researcher sighs or frowns when you can’t recall an item, you might change your behaviour in subsequent tasks to align with what you think the researcher wants. This is a classic example of demand characteristics at play.

In another instance, let’s say a study aims to measure the effectiveness of a new teaching method. If students know that the purpose is to evaluate this method, they might pay more attention, skewing the results.

Why are they problematic?

Demand characteristics introduce a form of bias into research studies. Participants, knowingly or unknowingly, alter their behaviour to fit the perceived expectations of the researcher. This can lead to false or skewed data, which in turn affects the reliability and validity of the study.

A study by Austin Lee Nichols and Jon K. Maner found that demand characteristics could even influence studies on social behaviour. In their research, they discovered that participants who were aware of the study’s aim were more likely to conform to social norms, thereby affecting the study’s outcome.

How can researchers control for demand characteristics?

• Single-blind and double-blind designs. One common method to control for demand characteristics is to use a single-blind or double-blind study design. In a single-blind study, the participants are unaware of the critical aspects of the study, such as which treatment group they are in. In a double-blind study, both the participants and the researchers are unaware of these details, further reducing the chance of bias.
• Deception. Another approach is to use deception. Researchers may mislead participants about the true aim of the study to prevent them from altering their behaviour. But ethical considerations come into play here, as deception can be controversial.
• Post-experimental questionnaires. Researchers can also use post-experimental questionnaires to assess the extent to which demand characteristics may have influenced participants. By asking participants what they believed the study was about and whether they changed their behaviour, researchers can gauge the impact of demand characteristics.

The ongoing debate

While controlling for demand characteristics is crucial, some argue that it’s almost impossible to eliminate them entirely. Every interaction between a researcher and a participant could potentially introduce new cues. Therefore, it’s essential for researchers to be aware of this limitation and to consider it when designing studies and interpreting results.

Takeaway

Demand characteristics are an unavoidable aspect of psychological research that can significantly impact the validity and reliability of a study. While methods like single-blind and double-blind designs, deception, and post-experimental questionnaires can help control for these characteristics, they are not foolproof. As researchers, being aware of the potential for demand characteristics to influence a study is the first step in mitigating their impact.

Lance McDonald, PhD is an experimental psychologist with a keen interest in research methodology.