Episodic memory formation rate varies over time partly due to fluctuations in attentional state during memory encoding. Emerging evidence suggests that fluctuations in pre- and/or post-stimulus attention during encoding impact subsequent memory performance. It remains unclear how these fluctuations may differentially impact the subsequent retrieval of items alone, compared to items + their contextual details (associative context memory). In this study, we explored this in 30 healthy younger adults (21-34 years old). We developed the Montreal Attention at Encoding (MAET) task where on each encoding trial, participants responded as quickly as possible to a central fixation cross that expanded in size after a random duration. They then had to encode a picture of an object and its spatial location. Memory for the object-location associations was tested during retrieval. Response time (RT) to the fixation cross presented prior to each object gauged pre-stimulus attention levels on a trial-by-trial basis, while RT to the fixation cross that ensued each object indexed post-stimulus attention levels. Within-subject logistic regressions were used to predict context and item memory performance from pre- and post-stimulus RTs. Results revealed that encoding pre-stimulus attentional levels did not differentially predict context vs. item memory. However, post-stimulus RTs did predict subsequent context retrieval such that, longer post-stimulus RT to the fixation was related to poorer subsequent context retrieval. This study introduces a novel paradigm for investigating the impact of attentional state at encoding on subsequent memory performance and indicate a link between post-stimulus delays in attention-related RT and associative encoding success.
bioRxiv Subject Collection: Neuroscience