English speaking kindergarteners sometimes incorrectly answer questions with medial wh-relativizers by apparently responding to the relativizer. For example, they might answer How did Lewis tell Sally what he picked? by saying what was picked (e.g., apples). In other words, they interpret it to mean: What did Lewis tell Sally (that) he picked? These errors are reminiscent of the wh-scope marking (WSM) construction found in languages like German, where the true wh-phrase appears medially while the scope of the wh-phrase is marked by an initial, contentless wh-phrase (Lutz, Muller, & von Stechow, 2000). deVilliers and Roeper (1995) argue these errors are due to children having an immature WSM-like grammar, whereas Lutken, Legendre, and Omaki (2020) argue they are due to immature processing. If children’s errors are due to an immature grammar, adults should not make WSM errors because their grammars are fully developed. If children’s WSM errors stem from their language processors being overtaxed, adults might also make WSM errors if they are similarly overtaxed. We present the results of two experiments in which we taxed adults’ processing mechanisms and examined their responses to questions with medial wh¬-relativizers. Adults read short, yet complex stories and answered questions following them. We also included a working memory task which adults did simultaneously in Experiment 1. We found that adults did make WSM errors in both experiments and they did so at a rate similar to children. Furthermore, adults were more likely to make errors – and WSM errors, specifically – when they simultaneously did the WM task. We suggest that our findings are consistent with an immature processing account of these errors.