The error-speed effect – characterized by a decreased performance in a second recognition task for stimuli that elicited fast error responses in a first recognition task – has so far been predominantly interpreted as evidence for the existence of misleading memory information. However, this neglects a possible alternative explanation, namely that the effect may instead be caused by moments of inattention during study. Here, we introduce a manipulation that allowed us to distinguish between words from the study phase that participants most certainly paid attention to and those they did not. We hypothesized that if moments of inattention cause the error-speed effect, this effect should disappear when considering only targets that verifiably received attention during study. However, our results (N = 89) suggest that this is not the case: The error-speed effect still occurs for targets that participants attended to during study and thus indeed seems to be caused by misleading memory evidence rather than by moments of inattention during study.