Cognitive neuroscientists rely on functional neuroimaging techniques and behavioral assays to investigate correlation between brain activation and cognitive processes. Researchers would also infer what cognitive process is engaged under a condition based on neuroimaging data. This is referred to as reverse inference or encoding paradigm and it has generated longstanding discussions among cognitive neuroscientists, data scientists and philosophers. The consensus is that it should be done with rigorous statistical methods and careful interpretations. Statistical methods and large collaborative databases and data processing tools have been developed to build classificatory or predictive models of reverse inference. However, these tools are not without pitfalls. The problem of cognitive process further complicates the problem since it is a latent variable and the wide discrepancy on the taxonomy and ontology of cognitive processes within the field. Online collaborative project has been set up to combat this problem, while others try to circumvent pre-established concepts by extracting latent variables from existing data or by focusing on the evolutionary prerequisite of cognition. A fundamental limitation of reverse inference is its dependency on correlational data, which lacks the explanatory power interventionist studies have. Models that seek to establish causal relation from time-series data can only provide weak inferences. Furthermore, the dynamic complexity of the brain network complicates the mechanism. This review provides an overview of reverse inference in cognitive neuroscience. It discusses advances in methods, limitations, and conceptual issues inherent within reverse inference, particularly addressing the challenges mentioned above.
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