Once fiercely rejected, the notion of delay-dependent forgetting from long-term memory has recently resurfaced. By this notion, the duration of the study-test delay predicts the magnitude of memory degradation. Our Representation Theory of Forgetting adopts the notion of delay-dependent forgetting, alongside interference due to similarity of representations as an additional cause of forgetting—rather than its sole cause, as has been largely argued in the past. This theory maintains that the causes of forgetting depend on the underlying memory representations. Because hippocampus-based memory representations are relatively distinct from one another, by the virtue of being associated with distinct contexts, they are not as likely as non-hippocampus representations to be forgotten due to interference from similar memories. Instead, as neurobiological evidence suggests, these representations may be forgotten over the passage of time. Thus, contextual-information should be particularly sensitive to delay-dependent forgetting in comparison to item-information. In the current study we tested this hypothesis by comparing the effects of short study-test delay (~2 min) to long delay (~15 min) on forgetting. In three experiments using three different memory paradigms, we obtained various measures of item- and contextual-information. Results converged to support our predictions: whereas most measures of contextual-information showed forgetting over time, item-information was less affected by delay and, at times, was not affected at all. Finally, different patterns of time-dependent forgetting of contextual-information were observed in recall and recognition, in line with the different roles of context in these tests. Our results provide novel evidence for the specific effects of delay on hippocampus-based, contextual memory representations.

一旦被强烈拒绝，从长期记忆中依赖于延迟的遗忘概念最近又浮出水面。按照这种想法，学习测试延迟的持续时间可以预测内存退化的程度。我们的“遗忘表示理论”采用了依赖于延迟的遗忘概念，并将由于相似表示而产生的干扰作为遗忘的另一个原因，而不是像过去已广泛讨论的唯一原因。该理论认为，遗忘的原因取决于底层的内存表示形式。由于基于海马的记忆表示形式彼此相对不同，这是由于它们与不同的上下文相关联，因此，由于受到类似记忆的干扰，被遗忘的可能性不像非海马表示形式。代替，正如神经生物学证据所暗示的那样，随着时间的流逝，这些表现可能会被遗忘。因此，与项目信息相比，上下文信息对依赖于延迟的遗忘尤其敏感。在当前的研究中，我们通过比较短期学习测试延迟（〜2分钟）与长时间延迟（〜15分钟）对遗忘的影响，检验了这一假设。在使用三种不同记忆范式的三个实验中，我们获得了项信息和上下文信息的各种度量。结果汇聚在一起，支持了我们的预测：尽管大多数上下文信息度量都显示出随着时间的流逝而遗忘，但项目信息受延迟的影响较小，有时甚至根本不受影响。最后，在回忆和识别中观察到了不同的时间依赖性的上下文信息遗忘模式，符合上下文在这些测试中的不同作用。我们的结果为延迟对基于海马的上下文记忆表示的特定影响提供了新的证据。