In the experiments on the Monty-Hall puzzle, a large majority of participants gives a response different from Experimenters' Bayesian solution. We analyze this discrepancy as a problem of interpretation of the revision process of probabilities, induced by the statement of the Monty-Hall puzzle. Experimenters' solution actually stems from a traditional focusing situation whereas participants may for pragmatic reasons, build an updating representation of the puzzle. We establish that the descriptive explanations for participants' modal response provided by the psychological literature on Monty-Hall such as the ones based on heuristics can be translated into the adequate rule of revision in this updating framework.