Using metaphors to explain concepts and data enhances the scientific testimony’s impact, meaning, and memory-value.
All thinking is metaphorical.
Robert Frost, (quoted in Shibles, 1974)
Forensic scientists are increasingly required to testify about their findings and their professional conclusions.1 To present clear and compelling testimony, forensic experts need more than their science training. They need effective and evidence-based communication skills. This article describes and illustrates why metaphors are such powerful vehicles for scientific testimony and presents a simple, but extremely effective method to offer clear and compelling forensic science testimony.
Forensic scientists are like translators. They must “translate” scientific procedure and opinion in ways that both educate and persuade jurors. Legal scholars recognize that narrative elements, such as metaphors, effectively negotiate those two world-views, language, and goals.2
Science, especially neuroscience, also tells us that metaphors function as significant cognitive tools for data interpretation and decision-making.3 Lawyers, politicians, war planners, peace planners, advertising and PR professionals, and psychotherapists have long used metaphors as tools to inform and to influence how people frame issues, prioritize choices, and calculate results. Metaphors have climbed out of literature courses and into court testimony.
Neuroscience and Using Forensic Metaphors
Metaphors associate dissimilar concepts across areas of the brain associated both with affect and cognition. The images used in metaphors connect to our own images to form powerful and persuasive cognitive associations. First, they collect neurons together to form constellations of images. “Neurons that fire together, wire together” is the most famous adage in neuroscience.4 It means that images and metaphors that ignite memories, thoughts, and feelings bundle together to form constellations of much more powerful thoughts. Because this bundling of neurons takes place across a wide area of the brain, the impact of the metaphor increases geometrically.
The following trial excerpt5 depicts how one forensic scientist explained the role of DNA to the jury under direct testimony.
Prosecutor: ...But what is DNA? I mean, we—we know it’s out there. What is it?
Forensic scientist: …It controls how you develop and function. You inherit half your DNA from your mother and half from your father, and the inherent DNA will stay the same throughout your lifetime.
Can you spot the metaphor? “Controls” is not a scientific analysis or description of how DNA works. “Controls” is a metaphor for how DNA works. It’s a metaphor because it connects two different images. We “control” our car. We “control” our TV remote. When the scientist used “controls,” they tapped into all jurors’ images of “control,” so that DNA doesn’t just equal “control.” The metaphor equals all the jurors’ expectations, memories, and motivations for controlling. The use of “control” now clusters with every other neuron connected to “control” in the juror’s mind. Like a word search on the internet yielding a zillion “hits,” the image expands itself ad infinitum. The well-placed metaphor goes viral in the mind of jurors in seconds.