Search Results

This chapter reviews event-related potential (ERP) studies of human memory. Topics covered include the relationship between ERPs and cognitive processing, studies of memory coding, and studies of memory retrieval (repetition effects and recognition memory).

The importance of understanding human memory search is hard to exaggerate: we build and live our lives based on what we remember. This chapter explores the characteristics of memory search, with special emphasis on the use of retrieval cues. We introduce the dependent measures that are obtained during memory search, such as accuracy and search time, and discuss how these have contributed to our understanding of human memory search. The three phases of memory search (initiation, progression, and termination) are discussed in relation to the strategies employed by the human retriever. Finally, the experimental paradigms used in the memory literature are compared to examples of animal foraging behavior to identify points of contact for developing a general cross-domain understanding of search processes.

This chapter shows that episodic retrieval and source recollection are associated with frontal lobe function. The role of the prefrontal cortex in such retrieval tasks appears to be related to on-line control of memory activations. That is, extraneous information at the time of recollection can significantly interfere with episodic retrieval and source recollection. Such interference effects appear more significant for source recollection than for the recollection of item information. Boosting or supporting executive control can improve source memory performance in patients with frontal lobe lesions.

In everyday parlance, memory is understood to be the ability to remember the mental traces of experience, of past events, and learned facts. This common view of memory is essentially based on the conscious acquisition and recall of information. Cognitive science and neuropsychology, however, have now made it imperative to broaden that definition. This chapter discusses the cortical substrate and mechanisms of memory. First, the making, organization, and retrieval of cognit, now as an item of memory, are explored. The formation of short-term memory, perceptual memory, and executive memory is considered, together with retrieval of memory. This chapter shows that memories are formed in cortical networks by associative principles and mechanisms; perceptual memory networks are hierarchically organized in posterior cortex of association; executive memory networks are hierarchically organized in frontal cortex; memory retrieval consists in the associative reactivation of its network, that is, the increased excitability and firing of its neurons; organized behavior results from the joint activation of perceptual and executive memory networks.

This chapter focuses on the importance of attention for long-term memory encoding and retrieval. Some attention is probably needed to perceive items adequately. Beyond that, one can distinguish between memory with less versus more attention devoted at the time of encoding. If little attention is devoted, one retains only implicit memory, showing up in indirect tests of memory and as procedural memory (knowing how to do something as opposed to knowing things about it) or a sense of familiarity with the material. These processes are encoded and retrieved with relative automaticity. With more attention comes the additional availability of explicit memory and recollection (including episodic memory, or memory for events one has experienced). Jacoby proposed a well-known model in which familiarity and recollection are independent but the present chapter challenges that view in favor of an alternative suggestion that the recollected material is a subset of familiar materials.

Research for which the idea that many basic cognitive processes can be described as fast, parallel, and automatic is reviewed. Memory retrieval/decision processes have often been ignored in the cognitive literature. However, in some cases, computationally complex processes can be replaced with simple passive processes. Cue-dependent retrieval from memory provides a straightforward example of how encoding, memory, and retrieval can interact. Three other examples are reviewed: inference in text processing, compound cue models for priming, and implicit memory. In each case, the research benefits from a focus on retrieval and decision processes. For implicit memory, consideration of these kinds of processes leads to a view of implicit memory different than hypothesizing new specialized memory systems. Finally, how behavioral data from simple decisions and the models that explain the behavior can be related to neuroscience research on neural firing rates are discussed.

This chapter discusses commonalities and differences in the cognitive mechanisms underlying different search tasks, such as spatial search, visual search, memory retrieval, action search, problem solving, and decision making. Three key issues relevant across all types of search are distinguished: (a) the initiation of search, (b) the maintenance and adaptive modification of the search process, and (c) the termination of search. As to search initiation, research is summarized concerning the effect of the number of cues on difficulty for executing search, and which factors structure the cue hierarchy. Discussion follows on how knowledge about metacognitive processes in memory might be used for better understanding the processes in maintenance of search, and heuristic principles for stopping search, possibly shared across different search tasks, are identified. Finally, consideration is given to how search processes might change as a function of experience and aging.

This chapter provides a complementary Bayesian analysis of the problem of memory retrieval. A Bayesian model that is able both to classify words into semantically coherent groups, merely from observing their co-occurrence patterns in texts, is used as the basis for understanding aspects not only of how some linguistic categories might be created, but also how relevant information can be retrieved, using probabilistic principles. This work can be viewed as a natural follow-on from Anderson and colleagues' pioneering rational analyses of memory (Anderson & Milson, 1989; Anderson & Schooler, 1991). This chapter uses innovations in information retrieval as a way to explore the connections between research on human memory and information retrieval systems. It also provides an example of how cognitive research can help information retrieval research by formalizing theories of knowledge and memory organization that have been proposed by cognitive psychologists.

Older adults are slower to acquire new cognitive skills requiring a shift from controlled (algorithmic) processing to automatic responding based on retrieving newly unitized information from memory. Research demonstrates that older adults’ delayed retrieval shift is a strategic avoidance of relying on memory when doing so would be successful, not just a function of age-related slowing in rates of associative learning. Older adults’ retrieval avoidance can be reduced by financial incentives to respond rapidly, recognition probes that demonstrate the accessibility of correct information, and other experimental manipulations. Item-level strategy reports show an exponential rise in retrieval strategy use with practice but not for all participants. A proportion of the older samples are retrieval strategy avoidant across the entire course of skill acquisition task practice. The chapter comments on the motivational nature of retrieval strategy avoidance and the possible practical consequences of a retrieval avoidance mode for older adults.

This chapter examines behavioural, neurophysiological, and neuroimaging studies that reveal dissociations between storage or retrieval of clearly distinct, global stimulus categories, less distinct stimulus categories, and fine-grained distinctions within object categories. These results clearly show that material-specific cortical networks exist which are systematically activated during long-term memory retrieval.

This chapter discusses the large-scale oscillatory population dynamics associated with episodic retrieval that have been suggested coordinates the binding and integration of distributed neural population activity. Oscillatory fluctuations of neuronal membrane potentials play an important role in the coordination of large-scale interactions of neural assemblies. Such oscillations are caused by the concerted action of long-range afferents, local interneurons, and the intrinsic properties of the neural membrane. The fluctuations of local field potentials (LFPs) accompanying oscillations of membrane potentials can be measured at different anatomical scales, ranging from invasive recordings of small neuronal populations to non-invasive recordings of large cortical assemblies from the surface of the scalp using EEG and magnetoencephalography (MEG).

This chapter reports the discussion of a group of mostly behavioral biologists, who attempt to put research on search from their own discipline into a framework that might help identify parallels with cognitive search. Essential components of search are a functional goal, uncertainty about goal location, the adaptive varying of position, and often a stopping rule. The chapter considers a diversity of cases where search is in domains other than spatial and lists other important dimensions in which search problems differ. One dimension examined in detail is social interactions between searchers and searchers, targets and targets, and targets and searchers. The producer-scrounger game is presented as an example; despite the extensive empirical and theoretical work on the equilibrium between the strategies, it is largely an open problem how animals decide when to adopt each strategy, and thus how real equilibria are attained. Another dimension that explains some of the diversity of search behavior is the modality of the information utilized (e.g., visual, auditory, olfactory). The chapter concludes by highlighting further parallels between search in the external environment and cognitive search. These suggest some novel avenues of research.

Similarity is a compelling part of everyday experience. In the visual world, objects that are similar in shape or color may seem to leap to our attention. In conceptual processing, we have an immediate sense of whether a pair of concepts is similar. Objects are assumed to be classified on the basis of their similarity to some stored category representation. Yet despite extensive work on mechanisms of similarity, there has been very little discussion of why and how similarity is important in cognitive processing beyond the general recognition that similarity often provides a good basis for generalization. This chapter examines the role of similarity in the cognitive architecture and the relationship of similarity to automatic processing. It discusses how similarity can influence both low-level processes like attention and memory retrieval and higher cognitive processes like analogical reasoning and decision making. It also considers a number of examples in which cognitive processing is influenced by the presence of similarities in a stimulus set.

This chapter reviews behavioural and psychological refractory period (PRP) experiments, which provide evidence for the dynamic organization of two qualitatively different operations involved in a task. These operations are the slow, large-scale systems related to attention, conscious processing, and effortful mental operations, and the dedicated circuits that can very rapidly and in parallel execute stereotyped programs typically related to encoding and memory retrieval. It discusses the temporal organization of mental operations that suggests that a decision involves systematic coactivation of parietal and premotor regions of the brain.

The long shadow cast by the minister’s rejection explains why Smith’s memory formed and re-formed as it did in the context of later experiences. In 1835 Joseph Smith consolidated, and his scribe recorded, a spontaneous memory of his first vision. It differs markedly from his other accounts primarily because it was cued spontaneously by a conversation, not by a premeditated effort to record autobiography. It shows that, given the right cues and context, he could make a memory that did not need to respond to the Methodist minister, whether to please him (as in 1832) or to rebuke him (as in 1838/39).