Objective: The objective of this study was to systematically document current methods and pro- tocols employed when using functional near-infrared spectroscopy (fNIRS) techniques in human factors and ergonomics (HF/E) research and generate recommen- dations for conducting and reporting fNIRS findings in HF/E applications. Method: A total of 1,687 articles were identified through Ovid-MEDLINE, PubMed, Web of Science, and Scopus databases, of which 37 articles were included in the review based on review inclusion/exclusion criteria. Results: A majority of the HF/E fNIRS investiga- tions were found in transportation, both ground and aviation, and in assessing cognitive (e.g., workload, working memory) over physical constructs. There were large variations pertaining to data cleaning, pro- cessing, and analysis approaches across the studies that warrant standardization of methodological approaches. The review identified major challenges in transparency and reporting of important fNIRS data collection and analyses specifications that diminishes study replicabil- ity, introduces potential biases, and increases likelihood of inaccurate results. As such, results reported in exist- ing fNIRS studies need to be cautiously approached. Conclusion: To improve the quality of fNIRS inves- tigations and/or to facilitate its adoption and integra- tion in different HF/E applications, such as occupational ergonomics and rehabilitation, recommendations for fNIRS data collection, processing, analysis, and report- ing are provided. Keywords: fNIRS, human factors, ergonomics, neuro- ergonomics INTRODUCTION Neuroergonomics has been an instrumental approach for human factors and ergonomics (HF/E) researchers to understand, evaluate, pre- dict, and improve elements of human perfor- mance (such as workload, training, stress, and fatigue) across several work settings, such as aviation and health care (Ayaz, Willems, et al., 2010; James et al., 2011; Mehta, 2016). Defined as the study of the human brain in relation to performance at work and everyday settings (Parasuraman, 2003; Parasuraman & Rizzo, 2007), neuroergonomics integrates theories and principles from ergonomics, neuroscience, and human factors to provide critical insights on the neuropsychological and neurophysiological mechanisms that drive human behavior, particu- larly in natural settings (Parasuraman, 2011). Neuroimaging techniques allow us to study the brain and the different neural and cognitive processes that occur naturally under different tasks. In addition, these tools provide a better overview of different diseases, disorders, and operator cognitive states regarding how they affect the body, and hence a better understand- ing of possible cures and/or intervention strate- gies to address the deficiencies in cognitive/ physical functions. Several neuroimaging tools are available that can be divided into two main categories: (a) indi- rect indicators of metabolic neural activity and (b) direct indicators of neural activity due to task- based stimuli. Corresponding to the first category are the functional magnetic resonance imaging (fMRI), positron emission tomography (PET), functional transcranial Doppler sonography (fTCD), and functional near-infrared spectros- copy (fNIRS). Of these four popular methods, only fNIRS and fTCD allow mobile studies, as 845275HFS XX X 10.1177/0018720819845275Human Factorsfnirs recommendations for hf/e researchresearch-article 2019 Address correspondence to Ranjana K. Mehta, Industrial & Systems Engineering, Texas A&M University, College Station, TX 77843, USA; e-mail: rmehta@tamu.edu. Methodological Approaches and Recommendations for Functional Near-Infrared Spectroscopy Applications in HF/E Research Yibo Zhu, Carolina Rodriguez-Paras, Joohyun Rhee, and Ranjana K. Mehta , Texas A&M University, College Station, USA HUMAN FACTORS Vol. XX, No. X, Month XXXX, pp. 1–30 DOI: 10.1177/0018720819845275 Article reuse guidelines: sagepub.com/journals-permissions Copyright © 2019, Human Factors and Ergonomics Society.