Retrieving studied materials often enhances subsequent learning of new materials (Pastötter & Bäuml, 2014). However, retrieval has also been shown to impair new learning (Finn & Roediger, 2013). In this article, we attempted to determine when retrieval enhances and when it impairs new learning. We argue that testing impairs new learning when one intermixes testing with new learning, which biases participants to relearn the tested information at the expense of the new information. We refer to this as the borrowed time hypothesis. Consistent with this idea, we reduced or eliminated test-impaired new learning by discouraging time borrowing. Moreover, testing enhanced new learning only when the test trials and new learning trials were presented in separate blocks. These results suggest that test-impaired new learning and test-enhanced new learning are based on different underlying mechanisms and that they are not simply the flipped side of the same coin.

There is an increasing need in eyewitness identification research to identify factors that not only influence identification accuracy but may also impact the confidence–accuracy (CA) relationship. One such variable that has a notable impact on memory for faces is viewing distance, with faces encoded from a shorter distance remembered better than faces encoded at longer differences. In four pre-registered experiments, using both laboratory and online samples, we compared faces viewed at a simulated viewing distance at two different levels (medium and far) to faces that were viewed at a very near-simulated distance. Distance was simulated using a Gaussian blur function with higher levels of blur corresponding to greater simulated distance. We found that both medium and far simulated distances impaired memory performance overall relative to no simulated distance, with increased distance resulting in poorer memory. However, only far simulated distances impaired the CA relationship. In a fourth experiment, we found that a pre-test warning did not ameliorate this impairment of the CA relationship for faces viewed at a far simulated distance. These findings suggest that even high-confidence identifications made for faces viewed from long distances should be disregarded, and that estimator variables that impact memory may degrade the CA relationship when memory is reduced to critical levels.

Interpolated testing can reduce mind-wandering and proactive interference, and improve note-taking. However, recent research using face-name-profession triads, has also shown that interpolated testing can impair new learning (Davis, Chan, & Wilford, 2017 Davis, S. D. , Chan, J. C. , & Wilford, M. M. (2017). The dark side of interpolated testing: Frequent switching between retrieval and encoding impairs new learning. Journal of Applied Research in Memory and Cognition, 6(4), 434–441. https://doi.org/10.1016/j.jarmac.2017.07.002 [Crossref], [Web of Science ®] , [Google Scholar] ). In the current study, we further examined the impact of switching from testing to new learning, but with objectively-true materials. The study employed a 2 (Interpolated task: Test vs. Restudy) × 3 (Task-switch frequency: 0, 11, 35) between-participants design. In two experiments, participants restudied or retrieved originally-learned flag-country associations and learned new flag-capital (Experiment 1) or flag-export (Experiment 2) associations. Task-switch frequency varied such that participants switched to new learning trial(s) after every restudy/test trial (35-switches), after every three restudy/test trials (11-switches), or did not switch at all (0-switch). The results further demonstrate that retrieving previously-learned material can impair learning of new associations by replicating Davis et al. ( 2017 Davis, S. D. , Chan, J. C. , & Wilford, M. M. (2017). The dark side of interpolated testing: Frequent switching between retrieval and encoding impairs new learning. Journal of Applied Research in Memory and Cognition, 6(4), 434–441. https://doi.org/10.1016/j.jarmac.2017.07.002 [Crossref], [Web of Science ®] , [Google Scholar] ) with objectively-true materials.