Episodic retrieval and forgetting.

Background: Intentional forgetting refers to the surprising phenomenon that we can forget previously successfully encoded memories if we are instructed to do so. Here, we show that participants cannot only intentionally forget episodic memories but they can also mirror the ‘‘forgetting performance’’ of an observed model. Methodology/Principal Findings: In four experiments a participant observed a model who took part in a memory experiment. In Experiment 1 and 2 observers saw a movie about the experiment, whereas in Experiment 3 and 4 the observers and the models took part together in a real laboratory experiment. The observed memory experiment was a directed forgetting experiment where the models learned two lists of items and were instructed either to forget or to remember the first list. In Experiment 1 and 3 observers were instructed to simply observe the experiment (‘‘simple observation’’ instruction). In Experiment 2 and 4, observers received instructions aimed to induce the same learning goal for the observers and the models (‘‘observation with goal-sharing’’ instruction). A directed forgetting effect (the reliably lower recall of to-be-forgotten items) emerged only when models received the ‘‘observation with goal-sharing’’ instruction (P,.001 in Experiment 2, and P,.05 in Experiment 4), and it was absent when observers received the ‘‘simple observation’’ instruction (P.1 in Experiment 1 and 3). Conclusion: If people observe another person with the same intention to learn, and see that this person is instructed to forget previously studied information, then they will produce the same intentional forgetting effect as the person they observed. This seems to be a an important aspect of human learning: if we can understand the goal of an observed person and this is in line with our behavioural goals then our learning performance will mirror the learning performance of the model. Citation: Racsmány M, Keresztes A, Pajkossy P, Demeter G (2012) Mirroring Intentional Forgetting in a Shared-Goal Learning Situation. PLoS ONE 7(1): e29992. doi:10.1371/journal.pone. 0029992 Editor: Jan Lauwereyns, Kyushu University, Japan Received April 27, 2011; Accepted December 9, 2011; Published January 5, 2012 Copyright: 2012 Racsmány et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work is connected to the scientific program of the ‘‘Development of quality-oriented and harmonized R+D+I strategy and functional model at BME (Budapest University of Technology and Economics, Hungary)’’ project and is supported by the New Hungary Development Plan (Project ID: TÁMOP-4.2.1/B-09/1/ KMR-2010-0002) and by OTKA (Hungarian National Science Foundation) K84019. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: racsmany@cogsci.bme. hu . These authors contributed equally to this work.