People can purposefully forget information that has become irrelevant, as is demonstrated in list-method directed forgetting (LMDF). In this task, participants are cued to intentionally forget an already studied list (list 1) before encoding a second list (list 2); this induces forgetting of the first-list items. Most research on LMDF has been conducted with short retention intervals, but very recent studies indicate that such directed forgetting can be lasting. We examined in two experiments whether core findings in the LMDF literature generalize from short to long retention intervals. The focus of Experiment 1 was on the previous finding that, with short retention interval, list-2 encoding is necessary for list-1 forgetting to arise. Experiment 1 replicated the finding after a short delay of 3 min between study and test and extended it to a longer delay of 20 min. The focus of Experiment 1 was on the absence of list-1 forgetting in item recognition, previously observed after short retention interval. Experiment 1 replicated the finding after a short delay of 3 min between study and test and extended it to longer delays of 20 min and 24 h. Implications of the results for theoretical explanations of LMDF are discussed.

人们可以有目的地忘记已经变得不相关的信息，如列表方法定向遗忘 (LMDF) 所示。在这个任务中，参与者被提示在编码第二个列表（列表 2）之前故意忘记一个已经研究过的列表（列表 1）；这会导致忘记第一个列表项。大多数关于 LMDF 的研究都是以较短的保留间隔进行的，但最近的研究表明，这种定向遗忘可能是持久的。我们在两个实验中检查了 LMDF 文献中的核心发现是否可以从短保留间隔推广到长保留间隔。实验 1 的重点是先前的发现，即在保留间隔较短的情况下，list-2 编码对于 list-1 遗忘的出现是必要的。实验 1 在研究和测试之间短暂延迟 3 分钟后复制了这一发现，并将其延长到 20 分钟的较长延迟。实验 1 的重点是在项目识别中没有 list-1 遗忘，之前在短保留间隔后观察到。实验 1 在研究和测试之间短暂延迟 3 分钟后复制了这一发现，并将其延长到 20 分钟和 24 小时的更长延迟。讨论了结果对 LMDF 理论解释的影响。