In a cognitive neuroscience laboratory, scientists make use of non-invasive brain stimulation (NIBS) technology to stimulate the brain at its specific locations. They employ an electroencephalogram (EEG) to read visualized neurophysiological changes to observe behavioral changes in visual attention. In How Scientific Instruments Speak, Bas de Boer explains the postphenomenological relationships among the actants involved in this scientific scenario – scientists, technological instruments, scientific objects and scientific knowledge – from theoretical and practical perspectives. In the case of neuroscience, de Boer is interested in unraveling how established frameworks manipulate – ‘appropriate’ is his term – scientific practice involving dynamic relations among scientists, instruments and observed objects, so ‘the (supposed) objectivity of scientific knowledge can be considered constitutive of’ human subjects and their intentionality (p.180). In other words, de Boer is interested in exploring how the scientist community’s assumptions on what should be considered objective can distort the objective principle the community is supposed to follow and exclude those objective findings that do not meet its expectations. De Boer’s book consists of two parts. The first is the theoretical section that teases out how instruments mediate the relations among the scientific actants. In the second, de Boer makes use of theoretical insights to single out the complicated networks in two neuroscientific cases.