Over the past decades commercial and academic market(ing) researchers have studied consumers through a range of different methods including surveys, focus groups, or interviews. More recently, some have turned to the growing field of neuroscience to understand consumers. Neuromarketing employs brain imaging, scanning, or other brain measurement technologies to capture consumers’ (brain) responses to marketing stimuli and to circumvent the “problem” of relying on consumers’ self-reports. This paper presents findings of an ethnographic study of neuromarketing research practices in one neuromarketing consultancy. Our access to the minutiae of commercial neuromarketing research provides important insights into how neuromarketers silence the neuromarketing test subject in their experiments and presentations and how they introduce the brain as an unimpeachable witness. This enables us conceptually to reconsider the role of witnesses in the achievement of scientific credibility, as prominently discussed in science and technology studies (STS). Specifically, we probe the role witnesses and silences play in establishing and maintaining credibility in and for “commercial research laboratories.” We propose three themes that have wider relevance for STS researchers and require further attention when studying newly emerging research fields and practices that straddle science and its commercial application.

The increasing attention to the brain in science and the media, and people's continuing quest for a better life, have resulted in a successful self-help industry for brain enhancement. Apart from brain books, foods and games, there are several devices on the market that people can use to stimulate their brains and become happier, healthier or more successful. People can, for example, switch their brain state into relaxation or concentration with a light-and-sound machine, they can train their brain waves to cure their Attention Deficit Hyperactivity Disorder (ADHD) or solve their sleeping problems with a neurofeedback device, or they can influence the firing of their neurons with electric or magnetic stimulation to overcome their depression and anxieties. Working on your self with a brain device can be seen as a contemporary form of Michel Foucault's "technologies of the self." Foucault described how since antiquity people had used techniques such as reading manuscripts, listening to teachers, or saying prayers to "act on their selves" and control their own thoughts and behaviours. Different techniques, Foucault stated, are based on different precepts and constitute different selves. I follow Foucault by stating that using a brain device for self-improvement indeed constitutes a new self. Drawing on interviews with users of brain devices and observations of the practices in brain clinics, I analyse how a new self takes shape in the use of brain devices; not a monistic (neuroscientific) self, but a "layered" self of all kinds of entities that exchange and control each other continuously.

Method sections in psychology articles differ in the amount of information they provide, or the level of specificity at which they do so. This can make incremental research (e.g., replication efforts) difficult, because potentially relevant methodological decisions or practices may not be reported. As yet, these unwritten practices have not been systematically studied; the current work represents a first attempt in this direction. For this paper, we interviewed 22 experimental psychologists in the Netherlands to find out about these unwritten aspects of experimenting, as well as their opinions and beliefs regarding these practices. Thematic analysis of the transcripts suggests that (a) experimental psychologists indeed employ a variety of methods that they consider relevant yet do not routinely report in method sections, and (b) these unwritten practices seem to fall into two broad categories: 'professionalism' and 'the production of good data'. We discuss implications for psychological research generally, and the replication debate more specifically.