Brain-based Memory Detection and the New Science of Mind Reading

An extensive body of neuroimaging research has shown that the brain responds differently when people encounter something they recognize from past experience relative to when they encounter something they have never before seen. If such a “neural signature” of recognition was sufficiently reliable, it could theoretically be used as a forensic tool to detect whether or not someone remembers a given person, place, object, voice, smell, or any other stimulus. Although brain-based memory detection techniques have already been used for forensic purposes by police and prosecutors in some countries, efforts to promote their more widespread adoption have been met with hesitation, given uncertainty about their efficacy and reliability. In this chapter, we offer a critical review of the scientific status of memory detection. We examine the ways that researchers have used neuroimaging approaches such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) to capture temporal and spatial brain activation profiles that seemingly index different recognition memory states. Some of the more recent work has specifically addressed forensically-relevant factors such as the use of real-world acquired memories, classification of individual subjects rather than analysis of group differences, and the effect of subjects’ deployment of evasive countermeasures. We also highlight the application of multivariate analysis techniques, which are capable of decoding brain activity patterns on individual trials, and thus can yield inferences about a participant’s memory for specific stimuli or event details. Despite substantial progress made in recent years, we discuss critical methodological shortcomings and biological limitations that may ultimately limit the forensic value of brain-based memory detection.