Editor's note: Frank Farley is a psychologist and L.H. Carnell Professor at Temple University, Philadelphia, and a former president of the American Psychological Association.

(CNN) - The trial is over. Casey Anthony is not guilty, and I believe we will learn that the jury saw through the most unreasonable and bizarre piece of the prosecution's case - the motive. Jurors followed the prosecution's instruction to "just use common sense," and found that the motive made none.

Without concrete evidence, the essence of this trial was psychology: How do emotion, love and mothering play a role; who is lying and how can we know that.

But the theories put forth were based on bad psychology. The prosecution said the motive was simple and two-pronged: Casey made a murderous decision because she wanted party time; and Caylee was getting to an age when she might be able to tell people about her mother's lies and activities. So Casey made a pre-emptive strike. These explanations were vigorously advocated by the prosecutors in their closing arguments and rebuttal as central to the jury's deliberations.

Arguments from prosecution and defense

No credible motivational psychology that I know of would support that a single mother who seemed to love her child and who had lots of back-up parenting, in the grandparents and perhaps even from a brother, would go through the careful planning and complex, unpredictable, scary process of killing and disposing of her child in order to get a bit more free time.

Editor's note: Douglas Keene is a litigation consultant with a national practice, and served as the 2008-2009 President of the American Society of Trial Consultants (ASTC). He is a clinical and forensic psychologist and lectures at the University of Texas at Austin School of Law in the Trial Advocacy program.

(CNN) - The jury in the Casey Anthony trial deliberated for two days before acquitting Anthony of the death of her young daughter. Those who have been focused on the trial are now going to shift to what such a rapid verdict means. At bottom, it means that the jury did the job it was sworn to do, and it didn't require lengthy deliberation. To the 12 people who matter, the correct verdict was clear.

Juries are dedicated to nothing more than they are to getting it right. A quick verdict or a lengthy deliberation: Either one is a sign of 12 people determined to do the best they can.

I have interviewed thousands of jurors over the last 20 years - in focus groups, mock trials, jury selection - and many are still talking about what they believe to be the crazy verdict in the McDonald's hot coffee case, or how the jury let O.J. Simpson get off.

Jurors speak passionately about how they would exert great care if it were up to them, and they are highly critical of juries that they think failed to pay attention to facts. Jurors don't want to reach a verdict that will bring ridicule on them, and they want to sleep well knowing that they did what they knew was just.

Quick verdicts in lengthy cases are not entirely unusual, and usually - but not always - point to several factors: