Attention and Effort

The 11th edition of Harrison's Principles of Internal Medicine welcomes Anthony Fauci to its editorial staff, in addition to more than 85 new contributors. While the organization of the book is similar to previous editions, major emphasis has been placed on disorders that affect multiple organ systems. Important advances in genetics, immunology, and oncology are emphasized. Many chapters of the book have been rewritten and describe major advances in internal medicine. Subjects that received only a paragraph or two of attention in previous editions are now covered in entire chapters. Among the chapters that have been extensively revised are the chapters on infections in the compromised host, on skin rashes in infections, on many of the viral infections, including cytomegalovirus and Epstein-Barr virus, on sexually transmitted diseases, on diabetes mellitus, on disorders of bone and mineral metabolism, and on lymphadenopathy and splenomegaly. The major revisions in these chapters and many

Harrison's Principles of Internal Medicine

This article considers the role of the hippocampus in memory function. A central thesis is that work with rats, monkeys, and humans--which has sometimes seemed to proceed independently in 3 separate literatures--is now largely in agreement about the function of the hippocampus and related structures. A biological perspective is presented, which proposes multiple memory systems with different functions and distinct anatomical organizations. The hippocampus (together with anatomically related structures) is essential for a specific kind of memory, here termed declarative memory (similar terms include explicit and relational). Declarative memory is contrasted with a heterogeneous collection of nondeclarative (implicit) memory abilities that do not require the hippocampus (skills and habits, simple conditioning, and the phenomenon of priming). The hippocampus is needed temporarily to bind together distributed sites in neocortex that together represent a whole memory.

Memory and the hippocampus: A synthesis from findings with rats, monkeys, and humans.

The concept of working memory proposes that a dedicated system maintains and stores information in the short term, and that this system underlies human thought processes. Current views of working memory involve a central executive and two storage systems: the phonological loop and the visuospatial sketchpad. Although this basic model was first proposed 30 years ago, it has continued to develop and to stimulate research and debate. The model and the most recent results are reviewed in this article.

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Working memory: looking back and looking forward

The purpose of this article is to review basic empirical results from the psychological literature in a way that provides a useful foundation for research on consumer knowledge. A conceptual organization for this diverse literature is provided by two fundamental distinctions. First, consumer expertise is distinguished from product-related experience. Second, five distinct aspects, or dimensions, of expertise are identified: cognitive effort, cognitive structure, analysis, elaboration, and memory. Improvements in the first two dimensions are shown to have general beneficial effects on the latter three. Analysis, elaboration, and memory are shown to have more specific interrelationships. The empirical findings related to each dimension are reviewed and, on the basis of those findings, specific research hypotheses about the effects of expertise on consumer behavior are suggested.

Dimensions of Consumer Expertise

Spatial and verbal components of the act of recall.

Four experiments are described which demonstrate a conflict between reading verbal messages and imagining the spatial relations described by those messages. Listening to the same messages did not p...

The suppression of visualization by reading.

Publisher Summary This chapter presents evidence that challenges major points in the usual, divergent treatment of perception, categorization, and episodic memory. Perceptual and categorical processing cannot be assumed to depend on high-level units that change only over many trials and that are relatively independent of context. The effect of attentive processing need not be the systematically discarded information about surface characteristics; many perceptual and conceptual judgments depend upon nominally irrelevant information about a source and format. Both generalizing and explicitly episodic memory tasks can be accomplished in several ways. The analytic extreme, emphasized in a usual cognitive framework, depends solely on relevant information. A nonanalytic procedure depends on tightly integrated combinations of relevant and irrelevant information. Perceptual identification and conceptual judgments are no less variable or context dependent than explicit memory for episodes. The chapter discusses the effects on perception and categorization of manipulations that have traditionally been employed in investigations of explicit episodic memory tasks.

Nonanalytic Cognition: Memory, Perception, and Concept Learning

When dealing with a newly learned rule, one is often aware of relying on previous episodes of applying the rule. The specific materials or problems to which the rule was originally applied seem to have some privilege, particularly when the rule initially seems quite abstract. Understanding a difficult rule, or at least understanding how to apply it, seems to occur in terms of previous concrete applications. This impression is corroborated by Ross in his interesting work on remindings in problem solving (Ross, 1984, 1987, 1989; Ross & Kennedy, 1990). He demonstrated that performance while learning a word processing program or learning to solve simple probability problems is influenced by specific analogies with previously encountered problems. But what happens to these prior episodes of problem solving when the rule is not difficult, or when one has had sufficient practice to make it no longer seem difficult? Introspectively, the prior examples seem to disappear from active processing, a suggestion reflected in a wide variety of theories in cognitive psychology. In this article we argue that under common conditions, prior episodes retain an important role in helping apply the rule to new material, well after clear awareness of the prior episodes has disappeared. We make an ecological argument for the conditions under which episode-based knowledge has continued value.

Specializing the operation of an explicit rule

Objective This paper aims to summarise the evidence supporting the role of experience-based, non-analytic reasoning (NAR) or pattern recognition as a central feature of expert medical diagnosis.

Methods  The authors examine a series of studies, primarily from their own research programme at McMaster University, that demonstrate that expert and novice diagnostic problem solving is based, to some degree, on similarity to a prior specific exemplar in the memory.

Results  The studies reviewed have shown NAR to be a component of diagnostic reasoning at all levels from novice to subspecialist, and in dermatology, electrocardiography and psychiatry. The retrieval process is rapid and is not available to retrospection. It may be based on visual similarity, but can also be present in verbal descriptions. Some evidence exists that the process is unlikely to be available to introspection. Further, early hypotheses based on NAR can result in the reinterpretaton of critical clinical findings.

Conclusions  Non-analytic reasoning is a central component of diagnostic expertise at all levels. Clinical teaching should recognise the centrality of this process, and aim to both enhance the process through the learning of multiple examples and to supplement the process with analytical de-biasing strategies.

Lee R. Brooks

Papers

Spatial and verbal components of the act of recall.

The suppression of visualization by reading.

Nonanalytic Cognition: Memory, Perception, and Concept Learning

Specializing the operation of an explicit rule

Non-analytical models of clinical reasoning: the role of experience.