--- - |2 Abstract Neuroergonomics is an emerging field that investigates the human brain in relation to behavioral performance in natural environments and everyday settings. Functional near‐infrared spectroscopy (fNIRS), a noninvasive brain‐monitoring technology that relies on optical techniques to detect changes of cortical hemodynamic responses to human perceptual, cognitive, and motor functioning, is an ideal candidate tool. Ultraportable wearable and wireless fNIRS sensors are already breaking the limitations of traditional neuroimaging approaches that have imposed limitations on experimental protocols, data‐collection settings, and task conditions at the expense of ecological validity. This review summarizes emerging trends for fNIRS applications, from aerospace to medicine, with diverse populations and towards clinical solutions. We will review recent studies, such as mental workload assessment of specialized operators performing standardized and complex cognitive tasks and development of expertise during practice of complex cognitive and visuomotor tasks (ranging from aircraft piloting and robot control). Various recent synergistic fNIRS applications for human–human and human–machine interaction, including synthetic speech perception, interpersonal neural synchronization, and brain computer interfaces, highlight the potential use and are ushering the dawn of a new age in applied neuroscience and neuroengineering. - Japanese Psychological Research, Volume 60, Issue 4, Page 374-386, October 2018.