Lest we forget: Does remembering new information help improve forgetting?

Information that was once relevant may cease to be important. How do we forget irrelevant information and how is this affected by remembering new information? We explored this by embedding a directed forgetting task in a visual long-term memory paradigm. Participants were shown a series of images. Each image was followed by the cue to Remember or Forget the previous image, or it was followed by a new image with the instruction to Remember-Both images or Replace the previous image with a new one. In a later recognition test, all images were tested. Directed forgetting was effective—we found worse memory for Forget than Remember images. However, we found no evidence that new information helped in forgetting old information. There was no difference between Forget and Replace images and no difference between Remember and Remember-Both images. Experiment 2 demonstrated that recognition was worse for images replaced by subcategory-related than unrelated images. Experiment 3 found no difference in memory between images replaced by high and low memorability images. Similarly, Experiment 4 found no difference in recognition for images replaced by low and high-value images (determined by points). Across all studies to-be-forgotten or replaced images were remembered less well than to-be-remembered images, demonstrating that information is getting removed from memory. However, we see very little evidence that remembering new information improves control over forgetting. Strikingly, forgetting of no longer relevant information is not influenced by instructions to replace that information with something else (unless the new information is conceptually related, which could be from interference at memory retrieval). Further, memory was not influenced by the memorability of new information, nor by whether it’s associated with high or low value. While we have many cognitive tools to influence how well we remember, control over how well we forget is quite limited.