By Dr. Ken Broda-Bahm:
"What's the "credibility fish," you ask? It is the shape in the image above: The graph that is made when measuring the credibility of each of two parties over the course of a simple mock trial. We ask the mock jurors to rate each party's credibility on a scale that ranges from 7 (highest) to 1 (lowest) at each of three phases. After they've heard only from the plaintiff, a few will have reservations or give the defendant the benefit of the doubt. But most should give strong credibility to the plaintiff and weaker credibility to the defense. Then, after hearing from the defense, that relationship should reverse itself. Hearing the rest of the story, most should see some problems in the plaintiff's case and some merit in the defense. Finally, after hearing the plaintiff's rebuttal, those ratings converge toward a midpoint. As the mock jurors head into deliberations, understanding of the two sides should even out, setting the stage for robust disagreement.
Graphing those shifting ratings, what you get is the shape of a rightward facing fish, just like the Christian car decal (but not the "Darwin" version with the feet on it). The party with the higher credibility should alternate with presentations, and then end up near the middle. Instead of trying to 'win' the mock trial by the end of presentations, the sponsoring party's aim should be to provide a realistic but very balanced presentation of each side in order to maximize the possibility for reasonable disagreement during the deliberation stage. Of course, every mock trial is going to be different, and sometimes the fish isn't there, or it might be fatter or thinner. But at the end of the day, the more it looks like a fish, the better you did at keeping the presentations balanced. In this post, I will share seven principles for maintaining this balance in order to make your mock trial as productive a 'fishing expedition' as possible.