forecastingprinciples.com Reviews of Important Papers on Forecasting
Before 1985 Reviews
Review of:

W. Larry Gregory, R. B. Cialdini and Kathleen M. Carpenter (1982), “Self-relevant scenarios as mediators of likelihood estimates and compliance: does imaging make it so?" Journal of Personality and Social Psychology, 42, 89-99.


This is what I call exciting applied research. The authors report on four experiments on scenarios. In this context, scenarios meant short stories, written by the experimenters, where the subjects were asked to imagine that the events were actually happening to them. It was hypothesized that subsequent predictions of the likelihood of the event would be increased because knowledge of the event would be more easily available. Here is a brief overview of the results of the four experiments where the scenarios groups imagined the event happening to them, but the control groups did not:

Experiments Subjects

Predicted likelihood

Control % Scenario %
1. How likely is it that you might someday be arrested for armed robbery regardless of whether you are innocent or guilty?

48 psychology students

9 18
2. What is the perceived probability that you will win a vacation trip? 100 high school psychology student 23 38
3. How likely is it that you might be arrested for shoplifting or petty theft? 39 psychology students 2 16

Actual outcome

4. Percentage of subjects who actually subscribed to cable TV within six weeks 79 residents of two middle class neighborhoods 20 47

Alternative explanations were examined in the four studies, but the availability hypothesis held up well. In my opinion, however, experiment four expands the notion of availability to include saliency. This was the only experiment in which the information was the same for both experimental and control groups (thus it was equally available). The experimental group, however, imagined themselves to be experiencing the benefits of cable TV. This increased saliency produced a substantial effect.

The practical implications are important. By casting information into a plausible story, you can increase a person's perceived probability that the event will occur. (This is an assumption that bas been made by a number of long-range planners.) Furthermore, the likelihood can be increased even more if the person will imagine that the event is actually happening. The latter implication is relevant not only for planning but for practical marketing problems, as shown by the cable TV study. In that study, the subscription rates were about double those that had been experienced in the area by the cable TV company. Just imagine the possibilities!