The Effects of Repeated Retrieval on Memory Reconstruction for Naturalistic Images

Episodic memory allows us to mentally revisit past experiences by reinstating neural representations of events. However, retrieval is not a passive replay but a dynamic process, leading memories to change each time they are retrieved. Testing effect research suggests that repeated retrieval strengthens memory by enhancing both generalised and episode-specific representations. However, the effects of repeated testing on the reconstruction of complex, naturalistic images remain largely unexplored. This study investigated how repeated retrieval influences memory representations by applying a cued recall task. Functional Magnetic Resonance Imaging (fMRI) data were collected as participants encoded and retrieved 96 verb-image pairs, with each image retrieved four times in random order. Some retrieval trials were followed by a partially occluded image that participants had to judge as the correct image associated. Behaviourally, subjective levels of recall gradually increased across repetitions, and recognition accuracy remained high across all trials. Univariate analyses revealed a shift from perceptual to higher-order semantic regions across retrieval repetitions, accompanied by a reduction in left prefrontal activity. Notably, control-related activations persisted in some frontal regions during later retrievals, suggesting ongoing demands for mnemonic monitoring. Representational Similarity Analysis (RSA) on item-specific representations revealed that repeated retrieval promoted both episode-specific representations and generalised memory traces. This study offers valuable insights into the mechanisms underlying memory reconstruction, highlighting how repeated retrieval shapes memory representations of naturalistic images.