Mutual influences between memory and attention
Keywords: attention
distraction
sleep
selective retrieval
long-term memory
memory

Memory and attention are two of the most fundamental components of our cognition. Crucially, they do not operate independently but instead display an intricate, interactive relationship: our memories can guide our attention, and our attentional focus can shape our emerging memories. The aim of this doctoral thesis was to illuminate these mutual influences between memory and attention during the three crucial stages of memory establishment: encoding, consolidation, and retrieval. After delineating the scope of the thesis and defining relevant concepts and terminology in an introductory chapter (Chapter I), three experimental chapters discuss work exploring the memory attention interplay at these three stages.
In Chapter II, a distractor was used to divert attention during a learning task, thus targeting the encoding phase. The results showed a significant disruptive effect of the distractor during learning. Interestingly, distraction during encoding did not impair overall accuracy of subsequent memory retrieval and did not compromise the utility of the memories in guiding attention. However, more granular measures of memory retrieval revealed systematic biases in the quality of memory representations. Electrophysiological markers also pointed to enduring effects of the distractor during encoding. These traces of the distractor at encoding suggest that inhibitory processes could have taken place but were not established enough to guide attention proactively or shape overall mnemonic accuracy.
In Chapter III, I attempted to modulate attention to a selective set of memories during consolidation by using targeted memory reactivations during a nap phase. During learning, searching for target locations in different categories of scenes was linked to distinctive tunes, which were novel and purposely composed for the study. Participants then had a nap opportunity during which electroencephalography was recorded. A subset of tunes was replayed during napping periods when the participant was judged to be in slow-wave sleep to reactivate spatial contextual memories linked to those particular scene categories, while tunes associated to the other categories were not replayed. Later in the day participants performed memory retrieval and memory-based orienting tasks to compare performance on replayed vs. non-replayed scene categories. The findings diverged from the frequent observations of sleep-based benefits on memory strength in the sleep literature. Indeed, sleep-based stimulation could even lead to potential detriments of the memory as attentional guide. The implications of these findings, and their reliability, are discussed.
The set of studies described in Chapter IV manipulated selective attention to contents within memories at the stage of memory retrieval. The approach of using cues to direct attention retroactively to memory content developed within the working-memory literature (retrocues) was adapted for use with long-term memory retrieval. Spatially informative retrocues were found to speed and improve the identification of memory targets as well as, given the right conditions, the spatial precision of the memory. To my knowledge, this comprises the first evidence for the efficacy of retrocues to investigate selective retrieval in long-term memory. These observations imply that the selective retrieval of long-term memories is susceptible to attentional modulation. The newly developed experimental approach shows promise for adaptation with advanced research methodologies, for different populations, and for various lines of investigation.