Histograms are widely used, but recent studies have shown that they are not as easy to interpret as it might seem. In this article, we report on three studies on the interpretation of histograms in which we investigated, namely, (1) whether the misinterpretation by university students can be considered to be the result of heuristic reasoning, (2) whether we could influence performance by stimulating or hindering the analytic processing of histograms, and (3) whether experts still show signs of this heuristic misinterpretation. We found that both university students and experts show signs of incorrect heuristic reasoning when comparing the mean of two data sets presented by histograms. Stimulating or hindering analytic processing did not affect performance. These indications of heuristic reasoning and the impossibility to affect this analytic processing suggest that the incorrect heuristic misinterpretation of histograms is very persistent. Implications for theory and methodology, scientific and educational practice are discussed.