Reports an error in "Testing during study insulates against the buildup of proactive interference" by Karl K. Szpunar, Kathleen B. McDermott and Henry L. Roediger III ("Journal of Experimental Psychology: Learning, Memory, and Cognition," 2008[Nov], Vol 34[6], 1392-1399). Incorrect figures were printed due to an error in the production process. A corrected version of Figure 5 is provided. (The following abstract of the original article appeared in record EJ823538.) Recent interest in the benefits of retrieval practice on long-term retention--the testing effect--has spawned a considerable amount of research toward understanding the underlying nature of this ubiquitous memory phenomenon. Taking a test may benefit retention through both direct means (engaging appropriate retrieval processes) and indirect means (fostering directed study). Here the authors report 4 experiments demonstrating a novel benefit of testing. Extended study sessions cause a buildup of proactive interference, but interpolating tests during the study sequence insulates against this negative influence. These findings highlight a unique benefit of testing and have important implications for study strategies.