The Experimental Study

The Experimental Study

What distinguishes an experiment from all other kinds of studies is that the experimenter manipulates the world. Rather than being just a passive observer, the experimenter intentionally makes some change and then observes the effect of the change.

Consider an experiment carried out by Céline Jacob, Nicolas Guéguen and Gaëlle Boulbry (2010). They wanted to know whether songs with kindly lyrics would tend to encourage people to behave in a more kindly manner. Before conducting their experiment, they first had listeners identify songs with kindly, empathetic, or prosocial lyrics. They also had listeners identify songs with comparatively neutral lyrics. They then matched the songs according to preference or liking. So the songs with the kindly lyrics weren’t rated by listeners as more or less enjoyable than the songs with the more neutral lyrics.

Over a six-week period, Jacob et al played the prosocial and neutral music in alternating sessions in a restaurant located along the Breton coast in France. During each session they calculated the amount of tips left by restaurant patrons. They found that when music with prosocial lyrics was played, patrons left significantly better tips than when music with neutral lyrics was played.

The variable manipulated by the experimenter is called the independent variable (or independent measure). The variable observed by the experimenter is called the dependent variable (or dependent measure).

In the case of the restaurant study, the manipulation was the type of music played. That is, the independent variable was the degree of prosocial content in the song lyrics. The observed variable was the percentage tipping. That is, dependent variable (or dependent measure) was tipping percentage.

In the simplest experimental design, there are two values given to the independent variable. These values might be music versus no-music; heavy-metal versus reggae, loud versus quiet, consonant versus dissonant, in-fashion versus out-of-fashion, or, (in the Jacob et al experiment), prosocial lyrics versus neutral lyrics. Do kindly lyrics encourage people to behave in a more kindly manner? Evidently, the answer is “yes,” at least when it comes to French songs played in a certain Breton restaurant.

In a basic experiment, observations will be made for two groups: the “treatment” group and the “control” group. A more elaborate experiment might have several different “treatment” levels or treatment conditions.

In a correlational study, we are often interested in the relationship between two variables, but we don’t directly manipulate one of the variables. Instead, we simply observe the pre-existing relationship between the two variables. In correlational studies, there is no independent variable that we change.

Reference

Céline Jacob, Nicolas Guéguen & Gaëlle Boulbry (2010). Effects of songs with prosocial lyrics on tipping behavior in a restaurant. International Journal of Hospitality Management, Vol. 29, pp. 761-763.