How do learners make decisions about how, what, and when to study, and why are their decisions sometimes ineffective for learning? In three studies, learners experienced a pair of contrasting study strategies (Study 1: interleaved vs. blocked schedule; Studies 2 & 3: retrieval practice vs. restudy) and rated their perceptions of each strategy before choosing one for future use. In all three studies, mediation analysis revealed that participants who perceived a strategy as more effortful rated it as less effective for learning and, in turn, were less likely to choose it for future study. Further, choosing the more effortful strategy was associated with better long-term retention (Study 3), contrary to participants' judgments. A final fourth study suggested that these relationships were not driven by the mere act of providing ratings. Our results thus support a misinterpreted-effort hypothesis in which the mental effort associated with many normatively effective learning strategies (desirable difficulties; Bjork & Bjork, 1992) leads learners to misinterpret them as ineffective for learning and consequently not to employ them in self- regulated learning.