Positron Emission Tomography (PET) scans are currently used by the popular press and the entertainment industry to provoke great excitement. This mysterious and fantastic technology is (seemingly) able to probe deep into the invisible brain and take photographs which can tell scientists more about how the brain works and doctors more about keeping it working. Periodicals now regularly present their readers with exciting multi-colored “brain pictures” that show how the brain of a depressed person, or a drug addict, or a woman is different from the brain of a “normal” person, a non-drug addicts, or a man. Furthermore these same images are used in civil and criminal trials and presented to juries to help them assess guilt or assign punishment.
In Picturing Personhood, medical anthropologist Joseph Dumit explores PET both as technology and cultural phenomenon. Through six chapters and five interludes he presents readers with a thorough ethno-history and ethnography of PET and PET-produced images. In so doing, Dumit interrogates the use of PET and PET imagery in technoscientific, biomedical, popular, and forensic discourse. Ultimately he argues, that while this is an exciting technology warranting further scientific and social scientific exploration, we—as a culture—need to be more careful and critically aware of the impacts of PET on our perceptions of identity.
Chapters one through three focus primarily on PET in the lab. Dumit presents an account of PET as a vastly interdisciplinary technoscientific practice. He highlights the roles of chemists, physicists, physicians, neuroscientists, and radiologists in both the development and use of PET. As Dumit explains, PET is a technology with disputed priority. There are at least three leading contenders for the honor. Rather than attempt the impossible task of ferreting out the “real” history of PET, Dumit offers three ethno-histories (culturally specific and explicitly perspectival histories) he collected from each of the three primary contenders. In presenting these histories Dumit also explores how each history includes different and distinct conceptions of the nature of technoscientific practice.
Following the ethno-histories, Dumit presents the results of his ethnographic research at several PET labs. He describes the process of PET image generation—a process he casts as highly contextual and often problematic. PET scans are the result of a highly sophisticated process, each stage involving decisions and assumptions that contribute to the ultimate representation of the data. Some of these major decisions include what type of radioactive substance to inject into the patient, what angle to scan at, which series of computer algorithms to use in interpreting the data, and which color-palate to use when representing the data. To further complicate matters, PET scan images despite being two-dimensional contain four dimensions of data. The colors used represent depth and change over time. Given this Dumit is understandably concerned with the interpretation of these images by non-experts, e.g. consumers of popular media and more importantly juries.
Marshalling a wide variety of theoretical approaches from anthropology, history, sociology, rhetoric, philosophy, and semiotics, Dumit interrogates how these images are deployed and understood in forensic and popular discourse. In chapters four to six, he explores the history of radiographic and PET imagery in American trial law, as well as the use of PET imagery in anti-drug campaigns. Ultimately, Dumit argues that an inappropriate cultural configuration of the PET image as akin to a photograph creates a situation where the PET image is seen to unproblematically depict the referent. Not only are the nuances of PET technology black boxed, PET images are understood as obviously authoritative. This has a wide variety of ramifications, those of forensics and biomedical identity most important to Dumit. It is in exploring this latter concern (biomedical identity) that Dumit concludes his book. He explores how the brain scans when employed as unproblematically referential configure biomedical identity for both “normals” and people suffering from various illnesses such as schizophrenia, Alzheimer’s, and depression.