Multitrial Design

Multiple Trials for the Participants

A classic case of a multiple-trial design involves the use of multiple chances or repetition of elements of the choices or exposure provided. Consider a classic bargaining investigation involving something like prisoner’s dilemma. What happens in the investigation is that the person makes a choice in what offer to make in the bargaining situation. After each choice, another trial or choice is offered and the reaction recorded. The impact of this kind of design is much like the scholastic aptitude test (SAT) where there exists a number of individual items and each provides a separate test or element for examination.

In the classic multitrial test, each element has value and often becomes recorded and analyzed separately.[Page 1057] If there is some element involved, like training or learning, the effect of additional interventions between evaluations may also be evaluated. Consider, for example, the weigh-in for a program trying to create weight loss. Each week, the participants should be practicing some new diet and exercise routine and the weigh-in provides a test or an evaluation after the process. Essentially, each week represents a trial and the weigh-in once a week indicates the outcome of the trial. Obviously, the expectation of success would be indicated by a set of numbers that demonstrated a consistent decline (loss of weight).

Multitrial designs can involve a sequence of interventions or efforts where a measurement takes place after each element. For example, one could test a sequence of message appeals for change in terms of fear, gain, and loss. After each message, the attitude/intention/behavior of the participant could be examined. The goal would be to examine whether the impact of the various messages represents a cumulative set of changes or message effectiveness or not.

Suppose that instead of cumulativeness, in which the order of the messages may not matter, the theoretical expectation involves a set of messages that have a maximum effectiveness when delivered in a specific order. In the previous example, there are six possible sequences using the combination of three messages (fear, gain, loss—fear, loss, gain—loss, gain, fear—loss, fear, gain—gain, loss, fear—gain, fear, loss). Providing different samples, the particular sequence and the measuring after each message permits a thorough assessment of the particular sequencing of the messages. In this example, the individual message exposure provides a separate trial and the multitrials occur for each set of participants. The comparison becomes which sequence of multiple trials generates the most effective outcome as measured by the dependent outcome.

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