Online research in philosophy

Miller (1956) summarized evidence that people can remember about seven chunks in short-term memory (STM) tasks. However, that number was meant more as a rough estimate and a rhetorical device than as a real capacity limit. Others have since suggested that there is a more precise capacity limit, but that it is only three to five chunks. The present target article brings together a wide variety of data on capacity limits suggesting that the smaller capacity limit is real. (...) Capacity limits will be useful in analyses of information processing only if the boundary conditions for observing them can be carefully described. Four basic conditions in which chunks can be identified and capacity limits can accordingly be observed are: (1) when information overload limits chunks to individual stimulus items, (2) when other steps are taken specifically to block the recoding of stimulus items into larger chunks, (3) in performance discontinuities caused by the capacity limit, and (4) in various indirect effects of the capacity limit. Under these conditions, rehearsal and long-term memory cannot be used to combine stimulus items into chunks of an unknown size; nor can storage mechanisms that are not capacity-limited, such as sensory memory, allow the capacity-limited storage mechanism to be refilled during recall. A single, central capacity limit averaging about four chunks is implicated along with other, noncapacity-limited sources. The pure STM capacity limit expressed in chunks is distinguished from compound STM limits obtained when the number of separately held chunks is unclear. Reasons why pure capacity estimates fall within a narrow range are discussed and a capacity limit for the focus of attention is proposed. Key Words: attention; enumeration; information chunks; memory capacity; processing capacity; processing channels; serial recall; short-term memory; storage capacity; verbal recall; working memory capacity. (shrink)

Memory and forgetting are inextricably intertwined. Any account of short-term memory (STM) should address the following question: If three, four, or five chunks are being held in STM, what happens after attention is diverted?

Cowan argues that the true short-term memory (STM) capacity limit is about 4 items. Functional neuroimaging data converge with this conclusion, indicating distinct neural activity patterns depending on whether or not memory task-demands exceed this limit. STM for verbal information within that capacity invokes focal prefrontal cortical activation that increases with memory load. STM for verbal information exceeding that capacity invokes widespread prefrontal activation in regions associated with executive and attentional processes that may mediate chunking processes (...) to accommodate STM capacity limits. (shrink)

Future work is needed to establish that pure short-term memory is a coherent individual difference attribute that is separable from traditional compound short-term memory measures. Psychometric support for latent pure short-term memory capacity will provide an important starting point for future fine-grained analyses of the intrinsic factors that influence individual differences in math skills.

We discuss the role of short-term auditory verbal storage within a working memory system. Data from single case studies of patients with left parietal lesions and selective impairment of memory span are discussed in order to address the question of the functions of short-term memory in language processing. The backup resource of auditory verbal short-term memory is required for those tasks that necessitate backtracking in order to integrate a verbal message within a developing (...) central cognitive representation. (shrink)

We challenge Ruchkin et al.'s claim in reducing short-term memory (STM) to the active part of long-term memory (LTM), by showing that their data cannot rule out the possibility that activation of posterior brain regions could also reflect the contribution of a verbal STM buffer.

We provide additional support for Cowan's claim that short term memory (STM) involves a range of 3–5 tokens, on the basis of language correlational analyses. If language is at least partly learned, linguistic dependency structure should reflect properties of the cognitive components mediating learning; one such component is STM. In this view, the range over which statistical regularity extends in ordinary text would be suggestive of STM span. Our analyses of eight languages are consistent with STM span being (...) about four chunks. (shrink)

Cowan defines a chunk as “a collection of concepts that have strong associations to one another and much weaker associations to other chunks currently in use.” This definition does not impose any constraints on the nature and number of elements that can be bound into a chunk. We present an experiment to demonstrate that such limitations exist for visual short-term memory, and that their analysis may lead to important insights into properties of visual memory.

This commentary focuses on how bottom-up neocortical models can be developed into eigenfunction expansions of probability distributions appropriate to describe short-term memory in the context of scalp EEG. The mathematics of eigenfunctions are similar to the top-down eigenfunctions developed by Nunez, despite different physical manifestations. The bottom-up eigenfunctions are at the local mesocolumnar scale, whereas the top-down eigenfunctions are at the global regional scale. Our respective approaches have regions of substantial overlap, and future studies may expand top-down eigenfunctions (...) into the bottom-up eigenfunctions, yielding a model of scalp EEG expressed in terms of columnar states of neocortical processing of attention and short-term memory. Footnotes1 The author is also affiliated with DRW Investments LLC, 311 S. Wacker Drive, Chicago, IL 60606. (shrink)

Consistent with Ruchkin and colleagues' proceduralist account, recent research on grouping and verbal-spatial binding in immediate memory shows continuity across short- and long-term retention, and activation of classes of information extending beyond those typically allowed in modular models. However, Ruchkin et al.'s account lacks well-specified mechanisms for the retention of serial order, binding, and the control of activation through attention.

The view that short-term memory should be conceived of as being a process based on the activation of long-term memory is inconsistent with neuropsychological evidence. Data from brain-damaged patients, showing specific patterns of impairment, are compatible with a vision of memory as a multiple-component system, whose different aspects, in neurologically unimpaired subjects, show a high degree of interaction.

Using explicit memory measures, Cowan predicts a new circumstance in which the central capacity limit of 4 chunks should obtain. Supporting results for such an experiment, using continuous old-new recognition, are described. With implicit memory measures, Cowan assumes that short-term repetition priming reflects the central capacity limit. I argue that this phenomenon instead reflects limits within individual perceptual processing modules.

This paper provides an interpretation of Hans-Jörg Rheinberger’s notions of epistemic things and historical epistemology . I argue that Rheinberger’s approach articulates a unique contribution to current debates about integrated HPS, and I propose some modifications and extensions of this contribution. Drawing on examples from memory research, I show that Rheinberger is right to highlight a particular feature of many objects of empirical research (“epistemic things”)—especially in the contexts of exploratory experimentation—namely our lack of knowledge about them. I argue (...) that this analysis needs to be supplemented with an account of what scientists do know, and in particular, how they are able to attribute rudimentary empirical contours to objects of research. These contours are closely connected to paradigmatic research designs, which in turn are tied to basic methodological rules for the exploration of the purported phenomena. I suggest that we engage with such rules in order to develop our own normative (epistemological) categories, and I tie this proposal to the idea of a methodological naturalism in philosophy of science. (shrink)

Using a particular formula for quantifying the effortlessness that Perruchet & Vinter suggest accompanies the detection of repetition among a set of representations concurrently in consciousness, it is shown that both the Sternberg function and the Cavanagh function, associated with immediate probed recognition tasks and memory span tasks, can be predicted.

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 (...) as larger than 55, the novel masked prime 37 paradoxically facilitated the “larger” response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory. (shrink)

Neural models have proposed how short-term memory (STM) storage in working memory and long-term memory (LTM) storage and recall are linked and interact, but are realized by different mechanisms that obey different laws. The authors' data can be understood in the light of these models, which suggest that the authors may have gone too far in obscuring the differences between these processes.

High temporal resolution event-related brain potential and electroencephalographic coherence studies of the neural substrate of short-term storage in working memory indicate that the sustained coactivation of both prefrontal cortex and the posterior cortical systems that participate in the initial perception and comprehension of the retained information are involved in its storage. These studies further show that short-term storage mechanisms involve an increase in neural synchrony between prefrontal cortex and posterior cortex and the enhanced activation of long-term (...) memory representations of material held in short-term memory. This activation begins during the encoding/comprehension phase and evidently is prolonged into the retention phase by attentional drive from prefrontal cortex control systems. A parsimonious interpretation of these findings is that the long-term memory systems associated with the posterior cortical processors provide the necessary representational basis for working memory, with the property of short-term memory decay being primarily due to the posterior system. In this view, there is no reason to posit specialized neural systems whose functions are limited to those of short-term storage buffers. Prefrontal cortex provides the attentional pointer system for maintaining activation in the appropriate posterior processing systems. Short-term memory capacity and phenomena such as displacement of information in short-term memory are determined by limitations on the number of pointers that can be sustained by the prefrontal control systems. Key Words: coherence; event-related potentials; imaging; long-term memory; memory; short-term memory; working memory. (shrink)

We focus on the functional specificity of theta and alpha oscillations and show that theta is related to working memory, whereas alpha is related to semantic long-term memory. Recent studies, however, indicate that alpha oscillations also play an important role during short-term memory retention and retrieval. This latter finding provides support for the basic hypothesis suggested by Ruchkin et al.

Although visual long-term memory (VLTM) and visual short-term memory (VSTM) can be distinguished from each other (and from visual sensory storage [SS]), they are embodied within the same modality-specific brain regions, but in very different ways: VLTM as patterns of connectivity and VSTM as patterns of activity. Perception and VSTM do not “activate” VLTM. They use VLTM to create novel patterns of activity relevant to novel circumstances.

Cowan assumes that chunk-based capacity limits are synonymous with the essence of a “specialized STM mechanism.” In a single experiment, we measured the capacity, or span, of long-term memory and found that it, too, corresponds roughly to the magical number 4. The results imply that a chunk-based capacity limit is not a signature characteristic of remembering over the short-term.

The identity of working-memory and long-term memory representations follows from many lines of evidence. However, the data provided by Ruchkin et al. are hardly compelling, as they make unproved assumptions about hypothetical generators. We cite studies from our lab in which congruent slow-wave topographies were found for short-term and long-term memory tasks, strongly suggesting that both activate identical cell assemblies.

Theories of binding have recently come into the focus of the consciousness debate. In this review, we discuss the potential relevance of temporal binding mechanisms for sensory awareness. Specifically, we suggest that neural synchrony with a precision in the millisecond range may be crucial for conscious processing, and may be involved in arousal, perceptual integration, attentional selection and working memory. Recent evidence from both animal and human studies demonstrates that specific changes in neuronal synchrony occur during all of these (...) processes and that they are distinguished by the emergence of fast oscillations with frequencies in the gamma-range. (shrink)

Episodic memory often is conceptualized as a uniquely human system of long-term memory that makes available knowledge accompanied by the temporal and spatial context in which that knowledge was acquired. Retrieval from episodic memory entails a form of first–person subjectivity called autonoetic consciousness that provides a sense that a recollection was something that took place in the experiencer’s personal past. In this paper I expand on this definition of episodic memory. Specifically, I suggest that (a) (...) the core features assumed unique to episodic memory are shared by semantic memory, (b) episodic memory cannot be fully understood unless one appreciates that episodic recollection requires the coordinated function of a number of distinct, yet interacting, “enabling” systems. Although these systems – ownership, self, subjective temporality, and agency – are not traditionally viewed as memorial in nature, each is necessary for episodic recollection and jointly they may be sufficient, and (c) the type of subjective awareness provided by episodic recollection (autonoetic) is relational rather than intrinsic – i.e., it can be lost in certain patient populations, thus rendering episodic memory content indistinguishable from the content of semantic long-term memory. (shrink)

Single-unit data from the cortex of monkeys performing working-memory tasks support the main point of the target article. Those data, however, also indicate that the activation of long-term memory is essential to the processing of all cognitive functions. The activation of cortical long-term memory networks is a key neural mechanism in attention (working memory is a form thereof), perception, memory acquisition and retrieval, intelligence, and language.

Working-memory retention as activated long-term memory fails to capture orchestrated processing and storage, the hallmark of the concept of working memory. The event-related potential (ERP) data are compatible with working memory as a mental workspace that holds and manipulates information on line, which is distinct from long-term memory, and deals with the products of activated traces from stored knowledge.

Global Health Needs and the Short-Term Medical Volunteer: Ethical Considerations Content Type Journal Article Pages 71-78 DOI 10.1007/s10730-011-9158-5 Authors Michele K. Langowski, Albert Gnaegi Center for Health Care Ethics, Salus Center, Saint Louis University, 3545 Lafayette, 5th Floor, St. Louis, MO 63104-1314, USA Ana S. Iltis, Department of Philosophy and Center for Bioethics, Health and Society, Wake Forest University, P.O. Box 7332, Winston-Salem, NC 27109, USA Journal HEC Forum Online ISSN 1572-8498 Print ISSN 0956-2737 Journal Volume Volume 23 Journal (...) Issue Volume 23, Number 2. (shrink)

Ruchkin et al. ascribe a pivotal role to long-term memory representations and binding within working memory. Here we focus on the interaction of working memory and long-term memory in supporting on-line representations of experience available to guide on-going processing, and we distinguish the role of frontal-lobe systems from what the hippocampus contributes to relational long-term memory binding.

Global short-term medical volunteerism is growing, and properly conducted, is a tool in the fight for greater global health equity. It is intrinsically ethical (i.e., it involves ethics at every step) and depends upon ethical conduct for its success. At present, ethical guidelines remain in their infancy, which presents a unique opportunity. This paper presents a set of basic ethical principles, building on prior work in this area and previously developed guidelines for international clinical research. The content of these (...) principles, and the benchmarks used to evaluate them, remain intentionally vague and can only be filled by collaboration with those on-the-ground in local communities where this work occurs. Ethical review must additionally take into consideration the different obligations arising from the type of institution, type of intervention, and type of relationship involved. This paper argues that frequent and formalized ethical review, conducted from the beginning with the local community (where this community helps define the terms of debate), remains the most important ethical safeguard for this work. (shrink)

Preference for partners with low fluctuating asymmetry (FA) may produce “good gene” benefits. However, Gangestad & Simpson's analysis does not exclude immediate benefits of fertility. Low FA is related to fertility in men and women. Short-term changes in FA are correlated with fertility in women. It is not known whether temporal fluctuations in the FA of men are related to short-term fertility status.

There is remarkable agreement between Ruchkin et al.'s psychophysiological views and my own model, based on developmental-experimental evidence, of working memory as activated long-term memory (LTM). I construe subvocal rehearsal as an operative scheme that maintains order information and demands attentional resources. Encoding and retrieving operations also demand attention. Another share of resources is used for keeping activated specific LTM representations.

Although we find Gangestad & Simpson's argument intriguing, we question some of its underlying assumptions, including: (1) that fluctuating asymmetry (FA) is consistently heritable; (2) that symmetry is driving the effects; (3) that use of parametric tests with FA is appropriate; and (4) that a short-term mating strategy produces more offspring than a long-term strategy.

There are over 800 seventh to tenth grade students at the College d’Enseignment Generale (CEG) School in Azové, Benin. Like most children in the developing world, these students lack access to clean water and basic sanitation facilities. These students suffer from parasitic infection and health ailments which could be directly offset with short term aid to supply water and medical aid. Promoting proper sanitation and providing the technology to implement water and wastewater treatment in the community will decrease childhood (...) and maternal disease and mortality rates in Azové. However, these measures may take several years to implement and will require a significant investment in the infrastructure of the school. Is it ethical to spend $10,000 towards the long-term goals of providing water and sanitation to the students of CEG Azové, compared to spending the same amount on short-term relief efforts? (shrink)

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 (...) as larger than 55, the novel masked prime 37 paradoxically facilitated the “larger” response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory. (shrink)

The term "false memories" has been used to refer to suggestibility experiments in which whole events are apparently confabulated and in media accounts of contested memories of childhood abuse. Since 1992 psychologists have increasingly used the term "false memory" when discussing memory errors for details, such as specific words within word lists. Use of the term to refer to errors in details is a shift in language away from other terms used historically (e.g., "memory (...) intrusions"). We empirically examine this shift in language and discuss implications of the new use of the term "false memories." Use of the term presents serious ethical challenges to the data-interpretation process by encouraging over-generalization and misapplication of research findings on word memory to social issues. (shrink)

Defining consciousness along the lines of Nagel, an organism has consciousness iff there is something it is like to be that organism, I relate three types of consciousness (phenomenal, access and reflexive) to the three types of short-term memory (sensory memories, short-term working memory and the central executive). The suggestion is that these short-term memory stores may be a key feature of consciousness.

With reference to Ruchkins et al.'s framework, this commentary briefly considers the history of working memory, and whether, heuristically, this is a useful concept. A neuropsychologically motivated critique is offered, specifically with regard to the recent trend for working-memory researchers to conceptualise this capacity more as a process than as a set of distinct task-specific stores.

The metric devised by Halford, Wilson & Phillips may have considerable potential in distinguishing between the working memory demands of different tasks but may be less effective in distinguishing working memory capacity between individuals. Despite the strengths of the metric, determining whether an effect is caused by relational complexity or by differential levels of expertise is currently problematic.

Fieldworkers (FWs) are community members employed by research teams to support access to participants, address language barriers, and advise on culturally appropriate research conduct. The critical role that FWs play in studies, and the range of practical and ethical dilemmas associated with their involvement, is increasingly recognised. In this paper, we draw on qualitative observation and interview data collected alongside a six month basic science study which involved a team of FWs regularly visiting 47 participating households in their homes. The (...) qualitative study documented how relationships between field workers and research participants were initiated, developed and evolved over the course of the study, the shifting dilemmas FWs faced and how they handled them. Even in this one case study, we see how the complex and evolving relationships between fieldworkers and study participants had important implications for consent processes, access to benefits and mutual understanding and trust. While the precise issues that FWs face are likely to depend on the type of research and the context in which that research is being conducted, we argue that appropriate support for field workers is a key requirement to strengthen ethical research practice and for the long term sustainability of research programmes. (shrink)

Recent evidence from our lab indicates that LTP shares an important property with memory consolidation: it is consolidated by natural reinforcement. Nevertheless, the hypothesis, that LTP-like mechanisms or other forms of enhanced synaptic efficacy are basic elements in learning is not unequivocally supported. Skepticism aside, LTP is an accessible experimental model that is optimally equipped for the investigation of the cellular and molecular machinery involved in synaptic weight changes.

Periodic and unexpected shortages of drugs, biologics, and even medical devices have become commonplace in the United States. When shortages occur, hospitals and clinics need to decide how to ration their available stock. When such situations arise, institutions can choose from several different allocation schemes, such as first-come, first-served, a lottery, or a more rational and calculated approach. While the first two approaches sound reasonable at first glance, there are a number of problems associated with them, including the inability to (...) make fine, individual patient-centered decisions. They also do not discriminate between what kinds of patients and what types of uses may be more deserving or reasonable than others. In this article I outline an ethically acceptable procedure for rationing drugs during a shortage in which demand outstrips supply. (shrink)

The problem of cortical integration is described and various proposed solutions, including grandmother cells, cell assemblies, feed-forward structures, RAAM and synchronization, are reviewed. One method, involving complex attractors, that has received little attention in the literature, is explained and developed. I call this binding through annexation. A simulation study is then presented which suggests ways in which complex attractors could underlie our capacity to reason. The paper ends with a discussion of the efficiency and biological plausibility of the proposals as (...) integration mechanisms for different regions and functions of the brain. (shrink)

Objective: The value of spontaneous EEG oscillations in distinguishing patients in vegetative and minimally conscious states was studied. Methods: We quantified dynamic repertoire of EEG oscillations in resting condition with closed eyes in patients in vegetative and minimally conscious states (VS and MCS). The exact composition of EEG oscillations was assessed by the probability-classification analysis of short-term EEG spectral patterns. Results: The probability of delta, theta and slow-alpha oscillations occurrence was smaller for patients in MCS than for VS. Additionally, (...) only patients in MCS demonstrated fast-alpha oscillation occurrence. Depending on the type and composition of EEG oscillations, the probability of their occurrence was either aetiology dependent or independent. The probability of EEG oscillations occurrence differentiated brain injuries with different aetiologies. Conclusions: Spontaneous EEG oscillations have a potential value in distinguishing patients in VS and MCS. Significance: This work may have implications for clinical care, rehabilitative programs and medical–legal decisions in patients with impaired consciousness states following coma due to acute brain injuries. (shrink)

This study examined the hypothesis that conditional reasoning involves visual short-term memory resources (Johnson-Laird, 1985). A total of 147 university students were given measures of verbal and visual short-term memory capacity and a series of concrete and abstract conditional reasoning problems. Results indicate that there is a positive correlation between verbal working memory capacity and reasoning with both concrete and abstract premises. A positive correlation was also obtained between visual working memory capacity and reasoning (...) with concrete premises. (shrink)

The goal of our target article is to establish that electrophysiological data constrain models of short-term memory retention operations to schemes in which activated long-term memory is its representational basis. The temporary stores correspond to neural circuits involved in the perception and subsequent processing of the relevant information, and do not involve specialized neural circuits dedicated to the temporary holding of information outside of those embedded in long-term memory. The commentaries ranged from general agreement (...) with the view that short-term memory stores correspond to activated long-term memory (e.g., Abry, Sato, Schwartz, Loevenbruck & Cathiard [Abry etal.], Cowan, Fuster, Grote, Hickok & Buchsbaum, Keenan, Hyönä & Kaakinen [Keenan et al.], Martin, Morra), to taking a definite exception to this view (e.g., Baddeley, Düzel, Logie & Della Sala, Kroger, Majerus, Van der Linden, Colette & Salmon [Majerus et al.], Vallar). (shrink)

Cowan's concept of a pure short-term memory (STM) capacity limit is equivalent to that of memory subitizing. However, a robust phenomenon well known in the Sternberg paradigm, that is, the linear increase of RT as a function of memory set size is not consistent with this concept. Cowan's STM capacity theory will remain incomplete until it can account for this phenomenon.

In this commentary, we focus on four points. First, we discuss the assertion that the unitary model explains dissociations that implicate multiple systems. Second, the distinct nature of information utilized in immediate- and delayed-recall supports the distinct memory systems view. Third, the variable nature of capacity limits corroborates this view. Finally, we review event-related fMRI results that suggest support for multiple systems.

Why do we remember events from our childhood as if they happened yesterday, but not what we did last week? Why does our memory seem to work well sometimes and not others? What happens when it goes wrong? Can memory be improved or manipulated, by psychological techniques or even 'brain implants'? How does memory grow and change as we age? And what of so-called 'recovered' memories? -/- This book brings together the latest research in neuroscience and psychology, (...) and weaves in case-studies, anecdotes, and even literature and philosophy, to address these and many other important questions about the science of memory - how it works, and why we can't live without it. (shrink)

Cowan has written a meticulous and thought-provoking review of the literature on short-term memory. However, reflections on one area of evidence, that of working memory span, shows the extent to which the research debate can be circumscribed by choice of experimental paradigms.

Shors & Matzel set up a straw man, that LTP is a memory storage mechanism, and knock him down without due consideration of the important relations among different levels of organization and analysis regarding LTP, learning, and memory. Assessing these relationships requires analysis and hypotheses linking specific brain regions, neural circuits, plasticity mechanisms, and task demands. The issue addressed by the authors is important, but their analysis is off target.

The experience of time, and more particularly of duration, has been studied rather separately from its functional fundament: the memory process. Yet, in the past few years some rather intriguing patterns of connection have emerged. Especially the effect of the usual distinction between immediate memory (IM), short term memory (STM) and long term memory (LTM) (Shiffrin and Atkinson 1969; Norman 1970) seems to provide some conceptual cement to link the two fields: time and (...) class='Hi'>memory. (shrink)

Memory, attention, and decision-making are three major areas of psychology. They are frequently studied in isolation, and using a range of models to understand them. This book brings a unified approach to understanding these three processes. It shows how these fundamental functions for cognitive neuroscience can be understood in a common and unifying computational neuroscience framework. This framework links empirical research on brain function from neurophysiology, functional neuroimaging, and the effects of brain damage, to a description of how neural (...) networks in the brain implement these functions using a set of common principles. The book describes the principles of operation of these networks, and how they could implement such important functions as memory, attention, and decision-making. -/- The topics covered include -/- The hippocampus and memory Reward and punishment related learning: emotion and motivation Visual object recognition learning Short term memory Attention, short term memory, and biased competition Probabilistic decision-making Action selection Decision-making -/- Also included are tutorial appendices on -/- Neural networks in the brain Neural encoding in the brain -/- 'Memory, Attention and Decision-Making' will be valuable for those in the fields of neuroscience, psychology, and cognitive neuroscience from advanced undergraduate level upwards. It will also be of interest to those interested in neuroeconomics, animal behaviour, zoology, evolutionary biology, psychiatry, medicine, and philosophy. The book has been written with modular chapters and sections, making it possible to select particular Chapters for course work. (shrink)

Prospective memory is required for many aspects of everyday cognition, its breakdown may be as debilitating as impairments in retrospective memory, and yet, the former has received relatively little attention by memory researchers. This article outlines a strategy for changing the fortunes of prospective memory, for guiding new research to shore up the claim that prospective memory is a distinct aspect of cognition, and to obtain evidence for clear performance dissociations between prospective memory and (...) other memory functions. We begin by identifying the unique requirements of prospective memory tasks and by dividing memory's prospective functions into subdomains that are analogous to divisions in retrospective memory (e.g., short- versus long-term memory). We focus on one prospective function, called prospective memory proper; we define this function in the spirit of James (1890) as requiring that we are aware of a plan, of which meanwhile we have not been thinking, with the additional consciousness that we made the plan earlier. We give an operational definition of prospective memory proper and specify how it differs from explicit and implicit retrospective memory and how it might be empirically assessed. (shrink)

One of the fundamental questions raised by Ruchkin, Grafman, Cameron, and Berndt's (Ruchkin et al.'s) interpretation of no distinct specialized neural networks for short-term storage buffers and long-term memory systems, is that of the link between perception and memory processes. In this framework, we take the opportunity in this commentary to discuss a specific working memory task involving percept formation, temporary retention, auditory imagery, and the attention-based maintenance of information, that is, the verbal transformation effect.

The structuralist program has developed a useful metascientific resource: ontological reductive links (ORLs) between the constituents of the potential models of reduced and reducing theories. This resource was developed initially to overcome an objection to structuralist ``global'' accounts of the intertheoretic reduction relation. But it also illuminates the way that concepts at a higher level of scientific investigation (e.g., cognitive psychology) become ``structured through reduction'' to lower-level investigations (e.g., cellular/molecular neuroscience). After (briefly) explaining this structuralist background, I demonstrate how this (...) resource illuminates an actual, emerging scientific example: the link between the psychological concept of a ``consolidation switch'' from short-term to long-term memory and the cellular/molecular mechanisms of the transition from early- to late-phases of long-term potentiation (LTP) (an important type of synaptic plasticity in mammalian hippocampus and cortex). (shrink)

This paper reports a study of the roles of visuo-spatial and verbal working memory capacities in solving a planning task - the five-disc Tower of London (TOL) task. An individual differences approach was taken. Sixty adult participants were tested on 20 TOL tasks of varying difficulty. Total moves over the 20 TOL tasks was taken as a measure of performance. Participants were also assessed on measures of fluid intelligence (Raven's matrices), verbal short-term storage (Digit span), verbal working (...) class='Hi'>memory span (Silly Sentence span), visuo-spatial short-term storage (Visual Pattern span and Corsi Block span), visuo-spatial working memory (Corsi Distance Estimation), visuo-spatial processing speed (Manikin test), and verbal speed (Rehearsal speed). Exploratory factor analysis using an oblique rotation method revealed three factors which were interpreted as (1) a visuo-spatial working memory factor, (2) an age-speed factor, and (3) a verbal working memory factor. The visuo-spatial and verbal factors were only moderately correlated. Performance on the TOL task loaded on the visuo-spatial factor but did not load on the other factors. It is concluded that the predominant goal-selection strategy adopted in solving the TOL relies on visuo-spatial working memory capacity and particularly involves the active ''inner scribe'' spatial rehearsal mechanism. These correlational analyses confirm and extend results previously obtained by use of dual task methods, (Phillips, Wynn, Gilhooly, Della Sala, & Logie, 1999). (shrink)

activity” has been considered to play a major role in the short-term maintenance of memories. Many studies since then have provided support for this view and greatly advanced our knowledge of the effects of stimulus type and modality on delay activity and its temporal dynamics (Funahashi et al., 1993; Fuster et al., 2000; Romo et al., 1999). In humans, working memory has also been a subject of intense investigation using scalp and intracranial electroencephalography (EEG, iEEG) as well as (...) magnetoencephalography (MEG), which provide estimates of local population activity. The published findings include reports of systematic changes in signal amplitude during working memory in the theta (Raghavachari et al., 2001; Tesche and <span class='Hi'>Karhu</span>, 2000), alpha (Gevins et al., 1997; Working memory has been linked to elevated single Jensen et al., 2002), beta (Tallon-Baudry et al., 1999). (shrink)

The experience of free will has causal consequences, albeit not immediate ones. Although Wegner recognizes this, his model failed to incorporate this causal link. Is this experience central to “what makes us human”? A broad acceptance of Wegner's claim that free will is illusory has significant societal and religious consequences, therefore the threshold of evidence needs to be correspondingly high.

Ruchkin et al. make a strong claim about the neural substrates of active information. Some qualifications on that conclusion are: (1) Long-term memories and neural substrates activated for perception of information are not the same thing; (2) humans are capable of retaining novel information in working memory, which is not long-term memory; (3) the content of working memory, a dynamically bound representation, is a quantity above and beyond the long-term memories activated, or the activity (...) in perceptual substrates. (shrink)

As opposed to the dismissive attitude toward reductionism that is popular in current philosophy of mind, a “ruthless reductionism” is alive and thriving in “molecular and cellular cognition”—a field of research within cellular and molecular neuroscience, the current mainstream of the discipline. Basic experimental practices and emerging results from this field imply that two common assertions by philosophers and cognitive scientists are false: (1) that we do not know much about how the brain works, and (2) that lower-level neuroscience cannot (...) explain cognition and complex behavior directly. These experimental practices involve intervening directly with molecular components of sub-cellular and gene expression pathways in neurons and then measuring specific behaviors. These behaviors are tracked using tests that are widely accepted by experimental psychologists to study the psychological phenomenon at issue (e.g., memory, attention, and perception). Here I illustrate these practices and their importance for explanation and reduction in current mainstream neuroscience by describing recent work on social recognition memory in mammals. (shrink)

``Neural computing'' is a research field based on perceiving the human brain as an information system. This system reads its input continuously via the different senses, encodes data into various biophysical variables such as membrane potentials or neural firing rates, stores information using different kinds of memories (e.g., short-term memory, long-term memory, associative memory), performs some operations called ``computation'', and outputs onto various channels, including motor control commands, decisions, thoughts, and feelings. We show a natural (...) model of neural computing that gives rise to hyper-computation. Rigorous mathematical analysis is applied, explicating our model's exact computational power and how it changes with the change of parameters. Our analog neural network allows for supra-Turing power while keeping track of computational constraints, and thus embeds a possible answer to the superiority of the biological intelligence within the framework of classical computer science. We further propose it as standard in the field of analog computation, functioning in a role similar to that of the universal Turing machine in digital computation. In particular an analog of the Church-Turing thesis of digital computation is stated where the neural network takes place of the Turing machine. (shrink)

Higher-order representation (HOR) theories posit that the contents of lower-order brain states enter consciousness when tracked by a higher-order brain state. The nature of higher-order monitoring was examined in light of current scientific knowledge, primarily in experimental perceptual psychology. The most plausible candidate for higher-order state was found to be conceptual short-term memory (CSTM), a buffer memory intimately connected with a semantic engine operating in the medium of the language of thought (LOT). This combination meets many of (...) the requirements of HOR theories, although falling short in some significant respects, most notably the inability of higher- order states to represent more than a small fraction of the information contained in primary states, especially in vision. A possible way round this obstacle is suggested, involving the representation of visual detail by means of ensemble concepts. (shrink)

Cognitive neuropsychology is that branch of cognitive psychology that investi- gates people with acquired or developmental disorders of cognition. The aim is to learn more about how cognitive systems normally operate or about how they are normally acquired by studying selective patterns of cognitive break- down after brain damage or selective dif?culties in acquiring particular cogni- tive abilities. In the early days of modern cognitive neuropsychology, research focused on rather basic cognitive abilities such as speech comprehension or production at the (...) single-word level, reading and spelling, object and face recognition, and short-term memory. More recently the cognitive-neuro- psychological approach has been applied to the study of rather more complex domains of cognition such as belief ?xation (e.g. Coltheart and Davies, 2000; Langdon and Coltheart, 2000) and pragmatic aspects of communication (e.g. McDonald and Van Sommers, 1993). Our paper concerns the investigation of pragmatic disorders in one clinical group in which such disorders are common, patients with schizophrenia, and what the study of such people can tell us about the normal processes of communication. (shrink)

The question of the imagination is rather like the question Augustine raised with regard to the nature of time. We all seem to know what it involves, yet find it difficult to define. For Descartes, the imagination was simply our faculty for producing a mental image. He distinguished it from the understanding by noting that while the notion of a thousand sided figure was comprehensible—that is, was sufficiently clear and distinct to be differentiated from a thousand and one sided figure—the (...) figure could not be clearly pictured in our mind. The representation of its sides exceeded our powers of imagination.[i] This view of the imagination as our ability to produce a mental image fails, however, to distinguish it from remembering. Let us say that I see an object and then I close my eyes, maintaining the image of the object. Is this imagining or short term memory? What about the case when I recall this image an hour later? Am I imagining or remembering it? Such examples make it clear that imagination, as distinct from memory, implies something more than the ability to produce a mental image. It involves, as Sartre pointed out, a certain attitude towards this image. Engaging in it, we deny its reality. In Sartre’s words, imagination “carries within it a double negation; first, it is the nihilation of the world (since the world is not offering the imagined object as an actual object of perception), secondly, the nihilation of the object of the image (it is posited as not actual) ...” (BN, p. 62). Imagination, then, represents the imagined as nonactual. (shrink)

Cognitive neuropsychology is that branch of cognitive psychology that investigates people with acquired or developmental disorders of cognition. The aim is to learn more about how cognitive systems normally operate or about how they are normally acquired by studying selective patterns of cognitive breakdown after brain damage or selective difficulties in acquiring particular cognitive abilities. In the early days of modern cognitive neuropsychology, research focused on rather basic cognitive abilities such as speech comprehension or production at the single-word level, reading (...) and spelling, object and face recognition, and short-term memory. More recently the cognitive-neuropsychological approach has been applied to the study of rather more complex domains of cognition such as belief fixation (e.g. Coltheart and Davies, 2000; Langdon and Coltheart, 2000) and pragmatic aspects of communication (e.g. McDonald and Van Sommers, 1993). Our paper concerns the investigation of pragmatic disorders in one clinical group in which such disorders are common, patients with schizophrenia, and what the study of such people can tell us about the normal processes of communication. (shrink)

Short-term memory, nonattentional task effects and nonspatial extraretinal representations in the visual system are signs of cognitive penetration. All of these have been found physiologically, arguing against the cognitive impenetrability of vision as a whole. Instead, parallel subcircuits in the brain, each subserving a different competency including sensory and cognitive (and in some cases motor) aspects, may have cognitively impenetrable components.

Cowan's review shows that a short-term memory limit of four items is consistent with a wide range of phenomena in the field. However, he does not explain that limit, whereas an existing theory does offer an explanation for capacity limitations. Furthermore, processing capacity limits cannot be reduced to storage limits as Cowan claims.

This study investigated the relationship between dream emotion and dream character identification. Thirty-five subjects provided 320 dream reports and answers to questions on characters that appeared in their dreams. We found that emotions are almost always evoked by our dream characters and that they are often used as a basis for identifying them. We found that affection and joy were commonly associated with known characters and were used to identify them even when these emotional attributes were inconsistent with those of (...) the waking state. These findings are consistent with the finding that the dorsolateral prefrontal cortex, associated with short-term memory, is less active in the dreaming compared to the wake brain, while the paleocortical and subcortical limbic areas are more active. The findings are also consistent with the suggestion that these limbic areas have minimal input from the dorsolateral prefrontal cortex in the dreaming brain. (shrink)

Cowan's analysis of human short-term memory (STM) and attention in terms of processing limits in the range of 4 items (or “chunks”) is discussed from the point of view of cognitive neuroscience. Although, Cowan already provides many important theoretical insights, we need to learn more about how to build further bridges between cognitive psychology and cognitive neuroscience.

Cowan postulates that the capacity of short-term memory is limited to the number of items to which attention can be simultaneously directed. Unfortunately, he endows attention with unexplained properties, such as being able to locate the most recent inputs to short-term memory, so his theory does little more than restate the data.

Cowan's experimental techniques cannot constrain subject's recall of presented information to distinct independent chunks in short-term memory (STM). The encoding of associations in long-term memory contaminates recall of pure STM capacity. Even in task environments where the functional independence of chunks is convincingly demonstrated, individuals can increase the storage of independent chunks with deliberate practice – well above the magical number four.

A physiological model for short-term memory (STM) based on dual theta (5–10 Hz) and gamma (20–60 Hz) oscillation was proposed by Lisman and Idiart (1995). In this model a memory is represented by groups of neurons that fire in the same gamma cycle. According to this model, capacity is determined by the number of gamma cycles that occur within the slower theta cycle. We will discuss here the implications of recent reports on theta oscillations recorded in humans (...) performing the Sternberg task. Assuming that the oscillatory memory models are correct, these findings can help determine STM capacity. (shrink)