Interactions between attention and memory

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Attention and memory cannot operate without each other. In this review, we discuss two lines of recent evidence that support this interdependence. First, memory has a limited capacity, and thus attention determines what will be encoded. Division of attention during encoding prevents the formation of conscious memories, although the role of attention in formation of unconscious memories is more complex. Such memories can be encoded even when there is another concurrent task, but the stimuli that are to be encoded must be selected from among other competing stimuli. Second, memory from past experience guides what should be attended. Brain areas that are important for memory, such as the hippocampus and medial temporal lobe structures, are recruited in attention tasks, and memory directly affects frontal-parietal networks involved in spatial orienting. Thus, exploring the interactions between attention and memory can provide new insights into these fundamental topics of cognitive neuroscience.

Introduction

Throughout the modern history of psychology and neuroscience, memory and attention have enjoyed center stage as fundamental processes of intellectual function. Yet most of this research has focused on these processes as separate topics. Memory studies have typically not explored the role of attentional selection and modulation of encoding, whereas attention studies commonly ignore the important role of perceptual experience and past knowledge. However, because memory has a limited capacity, it is crucial to understand which information is selected for encoding. Likewise, because attention operates in a world that is relatively stable over time, it is useful to rely on past experience to optimize selection. In fact, some aspects of attention and memory might even reflect the same processes. For example, memory retrieval might reflect a form of selective attention to internal representations [1, 2•].

Classic psychologists such as William James stated long ago that ‘we cannot deny that an object once attended to will remain in the memory, while one inattentively allowed to pass will leave no traces behind’ [3]. More recently, leading neuroscientists such as Eric Kandel have stated that one of the most important problems for 21st century neuroscience is to understand how attention regulates the processes that stabilize experiential memories [4]. Here, we review studies from the past two years that reveal progress towards understanding the interactions between attention and memory in neural systems.

Section snippets

Attention at encoding

A major question in many people's minds is how to improve memory. It is safe to say that attention helps to improve memory encoding but the details of this modulation remain unresolved. Also, although it is uncontroversial that attending to or focusing on a fact or event will enhance the likelihood of later memory, it is less clear how attention modulates and enhances implicit, unconscious memories — those traces of experience that we cannot articulate or overtly declare. Innovations in brain

The influence of memory on attention

Although it is more common to think about how attention improves memory, there is growing appreciation for how memory optimizes attention and perception. At a basic level, memory is undoubtedly fundamental to perception. One could not recognize their mother's face or a car as a car without the ability to match perceptual input with representations stored in memory.

Memory is especially important for perception when images are degraded. In visual area V4, neuronal responses to learned stimuli are

Conclusions

The relationship between attention and memory has long been recognized. Recent neuroimaging studies have begun elucidating how attentional control mechanisms might affect episodic and perceptual encoding and how, in turn, such control and orienting might be modulated by past experience. As this research progresses, the distinction between attention and memory becomes increasingly less clear. This might help to explain difficulties in resolving where perception stops and where memory begins [53,

Update

A recent event-related potential study provides further evidence that attention is directly cued by contextual memory. Johnson et al. [56] reported that electrophysiological measures of spatial attention reveal rapid orienting of attention to the target in contextual cuing tasks [43, 44].

References and recommended reading

Papers of particular interest, published within the period of review, have been highlighted as:

  • • of special interest

Acknowledgements

MMC was supported by National Institutes of Health EY014193. NBTB was supported by a foreign Natural Sciences and Engineering Research Council of Canada Post-Graduate Scholarship.

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