There is evidence that a story about design history is credible to the extent that it coheres with object affordances. Results that support this theory were generally obtained with artificial materials learned in laboratory experiments. In the current experiment, we extend these findings to real artifacts that occur naturally outside the laboratory. We presented participants of different levels of expertise, with real artifacts that cohered to different degrees with a proposed design history, and participants rated either the artifacts’ efficiency for the proposed design history function, or the credibility of the received story about their design history. Our results showed that coherent design histories are more credible, that expertise increases the ability to judge efficiency (not surprisingly), but that expertise does not affect the ability to judge credibility to the same extent that it affects efficiency. A post hoc explanation is offered for this interaction.