What memories do humans forget? One theory proposes that memories stored with moderate activation levels are weakened when faced with competitive stress so that they are particularly prone to be forgotten. However, research suggests that visual long-term memories are stronger than memories of other modalities, and therefore may never fall into this moderate activation zone. Here we tested these competing predictions by showing to-be-remembered pictures while we recorded event-related potentials (ERPs) indexing memory activation during encoding. We found that visual memories with medium levels of activation when first encoded were more prone to forgetting than memories with high or low encoding activation levels, but this only occurred if a memory was faced with competition. This study shows that we forget moderately activated memories when they are subjected to competition, regardless of the modality of experience.

人类会忘记哪些记忆？一种理论提出，当面临竞争压力时，以中等激活水平存储的记忆会减弱，因此它们特别容易被遗忘。然而，研究表明视觉长期记忆比其他方式的记忆更强，因此可能永远不会落入这个温和的激活区。在这里，我们通过显示待记住的图片来测试这些相互竞争的预测，同时我们记录事件相关电位 (ERP) 索引编码期间的记忆激活。我们发现第一次编码时具有中等激活水平的视觉记忆比具有高或低编码激活水平的记忆更容易遗忘，但这只有在记忆面临竞争时才会发生。