This project relates to the manuscript *"Confidence at the limits of human nested cognition"* likely to be published in *The Neuroscience of Consciousness* journal soon. Abstract: Metacognition is the ability to weigh the quality of our own cognition, such as the confidence that our perceptual decisions are correct. Here we ask whether metacognitive performance can itself be evaluated, or else metacognition is the ultimate reflective human faculty. Building upon a classic visual perception task, we show that human observers are able to produce nested, above-chance judgments on the quality of their decisions at least up to the fourth-order (i.e., meta-meta-meta-cognition). A computational model can account for this nested cognitive ability if evidence has a high-resolution representation, and if there are two kinds of noise, including recursive evidence degradation. The existence of fourth-order sensitivity suggests that the neural mechanisms responsible for second-order metacognition can be flexibly generalized to evaluate any cognitive process, including metacognitive evaluations themselves. We define the theoretical and practical limits of nested cognition, and discuss how this approach paves the way for a better understanding of human self-regulation. This project space contains 4 components: **Raw Data** contains the data in csv format **Matlab Analysis Scripts** contains the matlab code relevant for the analysis contributing to manuscripts Figures 2-4 and Supplementary Figures 2-5 **R- Analysis Scripts** contains the R code relevant for the analysis contributing to manuscript Figure 1 and Supplementary Figure 1 **Author Manuscript** contains our latest version of the manuscript, unformated.