Module 5

Credibility, gaps and bias: how memory works, why accounts differ, weighing sources fairly and guarding against your own bias

Once you have several accounts and some documents, the hard question begins: which to rely on, and how far. Lawyers and courts call this assessing credibility and reliability. Much of what is said about it is folk wisdom, such as the beliefs that a liar will not look you in the eye or that a confident witness must be right. Research on memory and on decision-making shows that these are poor guides. This module gives practical cautions. It shows how memory works, why honest accounts differ, what contradictions can and cannot show, how to weigh an account with factors you can state and defend, and how to guard against the biases that investigators carry into the work, above all the wish to find support for your own client’s story.

General education on investigating facts and forming a case theory, using invented people, businesses, documents and events. It is not legal advice, it does not state the law of any country and it is not a substitute for your own professional code, your regulator’s guidance or the rules of your court. Do not use it as a guide to contacting witnesses, recording conversations or gathering evidence in a real matter without the advice of a qualified lawyer in the place concerned.