Experiential and associative learning are essential to optimal decision making. However, research shows that, even when exposed to repeated trials, people often fail to learn probabilities and cause/effect covariations. Consistent with the counterfactual inflation hypothesis, it is proposed that counterfactuals can interfere with memory of repeated exposures and therefore inhibit learning. Five experimental studies tested counterfactual thinking as a potential mechanism underlying this learning deficit using a simple, biased coin flipping paradigm. Participants were instructed to either simply observe or to predict and observe outcomes of a biased coin being flipped in multiple trials (Experiments 1-4). In all four experiments, counterfactual thought frequency mediated the relationship between task instructions and the extent of bias detection (i.e., learning). Experiment 5 showed that mental simulations of alternative outcomes were especially deleterious to learning and decision making. Findings are discussed in light of experiential learning theory and applied implications.