Long-term retention of computer learning by patients with memory disorders

Like a rolling stone: Psychotherapy without (episodic) memory

People with profound amnesia still retain the capacity to learn about the emotional value of experiences, which is crucial in developing and sustaining interpersonal relationships. In a 2017 paper, we demonstrated for the first time (with patient JL) that transferential feelings develop across the therapeutic process, despite profound episodic memory impairment after medial temporal lesions. This paper reports a second case (GA) of a profoundly amnesic patient in psychotherapy, this time after lesions to the anterior fornix. The work with GA opens issues such as the differences and similarities to the previous case, counter-transference phenomena, and the effects of hyperphagia. The findings make it clear that many phenomena are common to both GA and JL, such as forgetfulness, various types of repetition, the importance of the therapeutic alliance, and the ability to make therapeutic gain. However, there were differences between the cases, for example as regards confabulation, which may relate to either pre-morbid personality or lesion site. The paper also discusses the way in which patients of this type bear the very status of psychotherapeutic work with profoundly amnesic patients. Where others have seen barriers and in principle problems in working with such patients, we see many opportunities.

Learning from errors is attributable to episodic recollection rather than semantic mediation

Many recent studies have shown that memory for correct answers is enhanced when an error is committed and then corrected, as compared to when the correct answer is provided without intervening error commission. The fact that the kind of errors that produced such a benefit, in past research, were those that were semantically related to the correct answer suggested that the effect may occur because the error provides a semantic stepping stone to the correct answer: the Semantic Mediation hypothesis. This hypothesis seems at odds with the finding that amnesicsgenerate answers, again including those studied by Tulving and his colleagues-who purportedly have spared semantic/implicit memory-experience enormous difficulties when they commit errors. Accordingly, the present experiments investigated whether the error-generation benefit seen in typicals was attributable Semantic Mediation or to Episodic Recollection. In Experiment 1, we used polysemous materials to create Congruent (e.g., wrist-palm) and Incongruent (e.g., tree-palm) cues for target words (e.g., HAND). In the Congruent condition, participants generated errors that were semantically related to the target (e.g., finger), and which could have provided a semantic mediator. In the Incongruent condition they generated errors that were unrelated to the target (e.g., coconut), and which, therefore, should not have provided a semantic mediator. The Congruent and Incongruent conditions both produced an error-generation benefit-contradicting the Semantic Mediation hypothesis. Experiment 2 showed that the error-generation benefit only occurred when the original error was also recollected on the final memory test. Indeed, in the Incongruent condition, when the error was not, itself, recalled, error generation resulted in a deficit in memory for the correct response. These results point to episodic/explicit, rather than semantic/implicit memory, as the locus of the 'learning from errors' benefits.

Neuropathology of a remarkable case of memory impairment informs human memory

Kent Cochrane (K.C.) has been investigated by researchers for nearly three decades after intracranial trauma from a motorcycle accident at age 30 resulted in a striking profile of amnesia. K.C. suffered severe anterograde amnesia in both verbal and non-verbal domains which was accompanied by selective retrograde amnesia for personal events experienced prior to the time of his injury (episodic memory), with relative preservation of memory for personal and world facts (semantic memory), and of implicit memory. This pattern of spared and impaired memory extended to spatial memory for large-scale environments and beyond memory to future imagining and decision-making. Post-mortem brain findings at age 62 included moderate diffuse atrophy, left orbitofrontal contusion, left posterior cerebral artery infarct, and left anterior frontal watershed infarct. Notably, there was severe neuronal loss and gliosis of the hippocampi bilaterally. The left hippocampus was severely affected anteriorly and posteriorly, but CA2, CA4, and the dentate gyrus (DG) were focally spared. There was associated degeneration of the left fornix. The right hippocampus showed near complete destruction anteriorly, with relative preservation posteriorly, mainly of CA4 and DG. Bilateral parahippocampal gyri and left anterior thalamus also showed neuron loss and gliosis. There was no evidence of co-existing neurodegenerative phenomena on beta-amyloid, phosphorylated tau, or TDP-43 immunostaining. The extent of damage to medial temporal lobe structures is in keeping with K.C.'s profound anterograde and retrograde amnesia, with the exception of the unexpected finding of preserved CA2/CA4 and DG. K.C.'s case demonstrates that relatively clean functional dissociations are still possible following widespread brain damage, with structurally compromised brain regions unlikely to be critical to cognitive functions found to be intact. In this way, the findings presented here add to K.C.'s significant contributions to our understanding of clinical-anatomical relationships in memory.

Effects of Saccade Induced Retrieval Enhancement on conceptual and perceptual tests of explicit & implicit memory

The effects of saccadic horizontal (bilateral) eye movements upon tests of both conceptual and perceptual forms of explicit and implicit memory were investigated. Participants studied a list of words and were then assigned to one of four test conditions: conceptual explicit, conceptual implicit, perceptual explicit, or perceptual implicit. Conceptual tests comprised category labels with either explicit instructions to recall corresponding examples from the study phase (category-cued recall), or implicit instructions to generate any corresponding examples that spontaneously came to mind (category-exemplar generation). Perceptual tests comprised of word-fragments with either explicit instructions to complete these with study items (word-fragment-cued recall), or implicit instructions to complete each fragment with the first word that simply 'popped to mind' (word-fragment completion). Just prior to retrieval, participants were required to engage in 30 s of bilateral vs. no eye movements. Results revealed that saccadic horizontal eye movements enhanced performance in only the conceptual explicit condition, indicating that Saccade-Induced Retrieval Enhancement is a joint function of conceptual and explicit retrieval mechanisms. Findings are discussed from both a cognitive and neuropsychological perspective, in terms of their potential functional and neural underpinnings.

Improvement of Cognitive Function after Computer-Based Cognitive Training in Early Stage of Alzheimer's Dementia

Background and Purpose

Cognitive training is known to be an effective tool in enhancing cognitive functioning. Research has also shown that playing video game improves certain aspects of visual attention and cognitive processing speed. The effect of computer-based cognitive training has not been demonstrated so far. This study therefore evaluated whether computer-based cognitive training improved the cognitive abilities in patients with early stage of Alzheimer's dementia.

Methods

Totally, 20 participants (early stage of Alzheimer's dementia) participated in this study. To test the effectiveness of computer-based cognitive training programs to cognition, all patients were randomly allocated to either an intervention group (n=10) or a control group (n=10). The intervention group regularly received 24 sessions of computer-based cognitive training, over a 12 week period. Neuropsychological examinations were conducted before and after this training period.

Results

After 12 weeks, the intervention group showed a significant change in language of Korean version of the Mini-Mental State Examination (K-MMSE), compared with the baseline cognitive examinations. Also, there was greater improvement in language, attention, calculation, verbal memory, and frontal function for the experimental group, as compared with controls.

Conclusions

Computer-based cognitive training might have beneficial effects on the general cognitive functions in early stage of Alzheimer's dementia.

Practical Ways of Improving Memory Storage and Retrieval Problems in Patients with Head Injuries

Memory disorders resulting from head injuries can be very distressing to both patients and carers. Understanding memory processes can be helpful in selecting the best memory strategies for particular patients. These strategies are discussed together with definitions of amnesic conditions and memory aids. The important message from using such memory strategies is that patients learning how to improve their poor memory have a far greater chance of improvement in the long term than those who simply rehearse items to be memorised.

Alzheimer memory training: Quizzes beat repetition, especially with more impaired

The present experiment was an attempt to replicate and discover the active agent in a memory/training intervention that had highly significant results with two early stage Alzheimer patients' and subsequently has been used successfully with a total of 12 additional patients.2 Two training methods were incorporated into one tape recorded intervention in an alternating treatments design: one method presented the information twice; the other presented the information once and immediately asked questions about it. Subjects were five mildly to severely impaired male Alzheimer patients and one man with an undiagnosed amnestic disorder. A shortened (quiz only) format was used with the severely impaired subject. To-be-learned information was randomly assigned to the two presentation formats. Taped sessions were presented three times daily for three days. Five of the six subjects learned much of the information presented (55 percent-86 percent) with both methods combined Retention of information learned at one and two week follow up ranged from 49 percent (one subject) to over 75 percent (three subjects). All four of the successful learners who used both methods learned more via quizzes than via repetition, with the lowest functioning subjects benefiting the most from the quizzes. At one week follow-up, the advantage of the quiz method was still substantial for the more impaired subjects, but had virtually disappeared or reversed itself for the high functioning subjects.

Evaluating an accessible web interface for older adults – the impact of mild cognitive impairment (MCI)

Purpose

– Cognitive changes occur with age and cognitive limitations can negatively influence computer use. Human-interaction studies show that especially older adults benefit considerably from using web platforms. The purpose of this paper is to measure the possible impact of cognitive impairment in web usability and to analyse the differences between older adults with and without cognitive impairment.

Design/methodology/approach

– In the presented pilot study, 50 older adults tested a web-based interface on a PC and tablet computer that was designed based on a styleguide for this specific user group. In two sessions participants had to conduct six tasks. In a third session older adults were left unsupervised in the laboratory where they were confronted with unexpected events triggered by a principal investigator.

Findings

– The performance results differed significantly between the two groups. Older adults with mild cognitive impairment (MCI) needed more time and were more likely to make mistakes when using a web platform. After analysing error data, it became apparent that errors made by older adults with MCI occurred due to a lack of orientation in websites.

Originality/value

– Little is known about web performance of older adults with cognitive impairment. The authors present valid data of this interesting target group and reveal their specific problems when handling a new online platform. The importance of a flat website hierarchy can be essential in developing senior friendly web pages. The authors also highlight methodological issues and illustrate the importance of qualitative information of the usability data, e.g. the different types of problems or errors.

Training to Optimize Learning after Traumatic Brain Injury

One of the major foci of rehabilitation after traumatic brain injury is the design and implementation of interventions to train individuals to learn new knowledge and skills or new ways to access and execute previously acquired knowledge and skills. To optimize these interventions, rehabilitation professionals require a clear understanding of how traumatic brain injury impacts learning, and how specific approaches may enhance learning after traumatic brain injury. This brief conceptual review provides an overview of learning, the impact of traumatic brain injury on explicit and implicit learning, and the current state of the science examining selected training approaches designed to advance learning after traumatic brain injury. Potential directions for future scientific inquiry are discussed throughout the review.

Priming and multiple memory systems: perceptual mechanisms of implicit memory

Abstract Research examining the relation between explicit and implicit forms of memory has generated a great deal of evidence concerning the issue of multiple memory systems. This article focuses on an extensively studied implicit memory phenomenon, known as direct or repetition priming, and examines the hypothesis that priming effects on various tasks reflect the operation of a perceptual representation system (PRS)-a class of cortically based subsystems that operate at a presemantic level and support non conscious expressions of memory. Three PRS subsystems are examined: visual word form, structural description, and auditory word form. Pertinent cognitive, neuropsychological, and neurobiological evidence is reviewed, alternative classificatory schemes are discussed, and important conceptual and terminological issues are considered.

Apathy After Traumatic Brain Injury: An Overview of the Current State of Play

Apathy is a decrease in behavioural, cognitive and emotional components of goal-directed behaviour. Clinically, it is characterised by diminished initiation, reduced concern, and decreased activity. Apathy is a common occurrence following traumatic brain injury (TBI), occurring in around 60% of people. Consequences are widespread, negatively impacting independence, social integration, rehabilitation outcome, vocational outcome, coping and caregiver burden. The current knowledge base on apathy following TBI is presented, with implications for clinical practice. This includes a review of clinical presentations, neuroanatomical and neurochemical substrates associated with apathy, and differential diagnoses. Instruments to measure apathy are presented, highlighting those with demonstrated reliability and validity for the TBI population. Current evidence for pharmacological and non-pharmacological methods of treatment is described, with a model for non-pharmacological interventions provided and discussion of challenges faced by clinicians when treating the patient with apathy. In the TBI arena, greater understanding of apathy and methods of treatment is pivotal given the frequency of occurrence and widespread negative consequences.

A procedural approach to remembering personal identification numbers among older adults

This study investigated whether a motor skill learning intervention could provide better memory for personal identification numbers (PINs) as compared to a control group. Younger (ages 18 to 40) and older (ages 61 to 92) participants were randomly assigned to conditions. All participants received three days of training consisting of 12 blocks of 12 trials each. Participants were tested immediately after training, after four days, and after seven days. Dependent measures were errors, latencies, and number of correct responses per minute. Younger participants were less error prone, faster, and produced more correct responses than older participants. Training condition (motor skill-based versus control training) had no significant effect on any of the dependent variables. Testing time had a significant effect on latency, and the effect of testing time on latency interacted with age group. In a second study, six older individuals diagnosed as having mild cognitive impairment (MCI) were trained using the motor skill learning intervention. Their performance was compared with that of the younger and older motor skill groups from the first experiment. The results showed that the older MCI group was significantly slower, more error prone, and produced fewer correct responses per minute than the older, normal group. Thus the presence of diagnosed MCI significantly impairs memory for PINs beyond the impairment expected from normal aging.

Cognitive rehabilitation of episodic memory disorders: from theory to practice

Memory disorders are among the most frequent and most debilitating cognitive impairments following acquired brain damage. Cognitive remediation strategies attempt to restore lost memory capacity, provide compensatory techniques or teach the use of external memory aids. Memory rehabilitation has strongly been influenced by memory theory, and the interaction between both has stimulated the development of techniques such as spaced retrieval, vanishing cues or errorless learning. These techniques partly rely on implicit memory and therefore enable even patients with dense amnesia to acquire new information. However, knowledge acquired in this way is often strongly domain-specific and inflexible. In addition, individual patients with amnesia respond differently to distinct interventions. The factors underlying these differences have not yet been identified. Behavioral management of memory failures therefore often relies on a careful description of environmental factors and measurement of associated behavioral disorders such as unawareness of memory failures. The current evidence suggests that patients with less severe disorders benefit from self-management techniques and mnemonics whereas rehabilitation of severely amnesic patients should focus on behavior management, the transmission of domain-specific knowledge through implicit memory processes and the compensation for memory deficits with memory aids.

Learning After Brain Injury by the Method of Vanishing Cues: A Case Study

Memory disorders feature amongst the most common complaints following brain injury. Theories of recovery and data derived from cognitive rehabilitation studies indicate that restoration of function is not a realistic goal, but recent work suggests that memory disordered patients often retain residual learning capabilities that can be utilized in teaching them certain kinds of information of practical use. This paper describes encouraging results obtained in teaching a patient computer related information by the method of vanishing cues. The patient learned more rapidly with this method than with anticipation learning, he showed evidence of good retention and, in contrast to earlier studies, he showed some evidence of generalization. However, the method may not be effective for all patients.

Improving website accessibility for people with early-stage dementia: a preliminary investigation

This study, conducted collaboratively with five men who have a diagnosis of early-stage Alzheimer's disease (AD), is the first stage of a formative research project aimed at developing a new website for people with dementia. Recommendations derived from a literature review of the implications of dementia-related cognitive changes for website design were combined with general web accessibility guidelines to provide a basis for the initial design of a new website. This website was compared with an equivalent site, containing the same information but based on an existing design, in terms of accessibility, ease of use, and user satisfaction. Participants were very satisfied with both sites, but responses did indicate some specific areas where one site was preferred over another. Observational data highlighted significant strengths of the new site as well as some limitations, and resulted in clear recommendations for enhancing the design. In particular, the study suggested that limiting the size of web pages to the amount of information that can be displayed on a computer screen at any one time could reduce the level of difficulty encountered by the participants. The results also suggested the importance of reducing cognitive load through limiting the number of choices required at any one time, the very opposite of the ethos of much website design.

The case of K.C.: contributions of a memory-impaired person to memory theory

K.C. has been investigated extensively over some 20 years since a motorcycle accident left him with widespread brain damage that includes large bilateral hippocampal lesions, which caused a remarkable case of memory impairment. On standard testing, K.C.'s anterograde amnesia is as severe as that of any other case reported in the literature, including H.M. However, his ability to make use of knowledge and experiences from the time before his accident shows a sharp dissociation between semantic and episodic memory. A good deal of his general knowledge of the world, including knowledge about himself, is preserved, but he is incapable of recollecting any personally experienced events. In displaying such "episodic amnesia," which encompasses an entire lifetime of personal experiences, K.C. differs from many other amnesic cases. Here, we document for the first time the full extent of K.C.'s brain damage using MRI-based quantitative measurements. We then review the many investigations with K.C. that have contributed to our understanding not only of episodic and semantic memory but also to the development of other aspects of memory theory. These include the distinction between implicit and explicit memory, the prospect of new learning in amnesia, and the fate of recent and remote memory for autobiographical and public events, people, and spatial locations.

Puzzling thoughts for H. M.: can new semantic information be anchored to old semantic memories?

Researchers currently debate whether new semantic knowledge can be learned and retrieved despite extensive damage to medial temporal lobe (MTL) structures. The authors explored whether H. M., a patient with amnesia, could acquire new semantic information in the context of his lifelong hobby of solving crossword puzzles. First, H. M. was tested on a series of word-skills tests believed important in solving crosswords. He also completed 3 new crosswords: 1 puzzle testing pre-1953 knowledge, another testing post-1953 knowledge, and another combining the 2 by giving postoperative semantic clues for preoperative answers. From the results, the authors concluded that H. M. can acquire new semantic knowledge, at least temporarily, when he can anchor it to mental representations established preoperatively.

A comparison and evaluation of the predictions of relational and conjunctive accounts of hippocampal function

Relational and conjunctive memory theory each postulate that the hippocampus participates in the formation of long-term memory representations comprised of associations between multiple elements. The goals of the current work were to clarify and contrast these theories by outlining the nature of the representations that are spared vs. impaired following hippocampal damage according to each theoretical perspective. Relational theory predicts that hippocampal lesions will impair performance on tasks that require the formation of new long-term representations in which distinct elements must be regarded in relation to all other elements. Representations that remain intact despite hippocampal damage include separate representations of distinct individual elements or multiple stimuli fused into a static "blend" such as several elements viewed from one vantage point. Additionally, the relational account predicts that rapid incidental online processing of the relations can be achieved through structures other than the hippocampus, but this information will not be stored. In contrast, conjunctive theory predicts that hippocampal damage will impair the rapid formation of unitary representations that contain features of elements and their relative relationships bound in an inflexible manner. Deficits in the rapid formation of these conjunctive representations result in impaired performance on tasks that require rapid incidental stimulus binding. However, intact formation of conjunctive representations can occur over multiple trials in the service of problem solving. Using these theoretical frameworks, recent findings from the human and nonhuman animal literature are reexamined in order to determine whether one theory better accounts for current findings. We discuss empirical studies that serve as "critical experiments" in addressing the relational vs. conjunctive debate, and find that the predictions of relational theory are supported by existing findings over those from the conjunctive account.

Historical review of computer-assisted cognitive retraining

OBJECTIVES

This article details the introduction and development of the use of microcomputers as adjuncts to traditional cognitive rehabilitation of persons with acquired brain injury.

SUMMARY

The initial application of video games as therapeutic recreation in the late 1970s was soon followed in the early 1980s by the use of the first personal computers and available educational software. By the mid-1980s, both the IBM PC and Macintosh platforms were established, along with simplified programming languages that allowed individuals without extensive technical expertise to develop their own software. Several rehabilitation clinicians began to produce and market specially written cognitive retraining software for one or the other platform. Their work was detailed and reviewed, as was recently released software from commercial sources. The latter discussion included the latest developments in the rehabilitation applications of personal digital assistants and related organizing, reminding, and dictation devices. A summary of research on the general and specific efficacy of computer-assisted cognitive retraining illustrated the lingering controversy and skepticism that have been associated with this field since its inception.

CONCLUSIONS

Computer-assisted cognitive retraining (CACR) can be an effective adjunct to a comprehensive program of cognitive rehabilitation. Training needs to be focused, structured, monitored, and as ecologically relevant as possible for optimum effect. Transfer or training or generalizability of skills remains a key issue in the field and should be considered the key criterion in evaluating whether to initiate or continue CACR.

Acquisition of novel semantic information in amnesia: effects of lesion location

Two patients with severe global amnesia are described who differ in the extent to which they have acquired new semantic information. Patient SS, who has extensive medial temporal lobe damage including the hippocampus as well as surrounding cortical areas, has failed to acquire virtually any new information regarding vocabulary or famous faces that entered the public domain since the onset of his amnesia. In contrast, patient PS, who has a selective lesion of the hippocampus proper, has gained a sense of familiarity of novel vocabulary and famous people, even though her effortful retrieval of this new semantic knowledge remains impaired. These findings extend to amnesia of adult onset, the proposal of Vargha-Khadem and colleagues that in patients with selective hippocampal injury, cortical areas surrounding the hippocampus may play an important role in new semantic learning [Vargha-Khadem, F., Gadian, D.G., Watkins, K. E., Connelly, A., Van Paesschen, W. and Mishkin, M., regarding the importance of the subhippocampal cortices in the mediation of new semantic learning in children with hippocampal lesions, Science, 1997, 277, 376-380].

Insights from semantic dementia on the relationship between episodic and semantic memory

An influential theory of long-term memory, in which new episodic learning is dependent upon the integrity of semantic memory, predicts that a double dissociation between episodic and semantic memory is not possible in new learning. Contrary to this view, we found, in two separate experiments, that patients with impaired semantic memory showed relatively preserved performance on tests of recognition memory if the stimuli were perceptually identical between learning and test. A significant effect of semantic memory was only seen when a perceptual manipulation was introduced in the episodic task. To account for these findings, we propose a revision to current models of long-term memory, in which sensory/perceptual information and semantic memory work in concert to support new learning.

Are the benefits of errorless learning dependent on implicit memory?

The effectiveness of errorless and errorful learning methods was compared in two experiments in which a group of memory-impaired individuals learned lists of single words. In both experiments, error prevention during learning resulted in higher levels of cued recall performance than trial-and-error learning. Experiment 1 showed that the beneficial effects of the errorless learning method extended over a delay of up to 48 hr and were also observed in free recall. The hypothesis that the benefits of errorless learning rely upon implicit memory was tested in Experiment 2. No evidence was found to support the hypothesis. Implicit memory was observed following both errorless and errorful learning, but there was no indication that enhanced performance in the errorless condition could be accounted for by implicit memory. There was no correlation between performance on a direct test (cued recall) and performance on an indirect test (fragment completion) for the same materials. Furthermore, the extent of priming was no greater for recalled items than non-recalled items in the cued recall test. It is proposed that the benefits of errorless learning in this paradigm stem from the effects of error prevention on residual explicit memory.

Beyond one-bun, two-shoe: recent advances in the psychological rehabilitation of memory disorders after acquired brain injury

Memory disorders are one of the most frequent types of cognitive impairment encountered in neurological populations. The more severe degrees of such impairment case major disability and handicap, and have a profound impact on a person's capacity to engage in independent living. To date, commonly used remediation strategies range from drills and practice, including computer-based tasks, to mnemonic techniques and memory notebooks. In general, these therapies have met with varying degrees of success. The last decade has seen exciting developments in remediation techniques for memory disorders, a number of which are based on implicit learning skills, as well as programmes tailored to an individual's unique pattern of deficits. The present paper provides an overview of this literature and discusses issues relating to their application in rehabilitation programmes.

Management of attention and memory disorders following traumatic brain injury

Disorders of attention, memory, and executive function are common sequelae in children who have sustained traumatic brain injuries. Given the persistent nature of these deficits, there is a need for efficacious remedial approaches. Typically, remediation is approached, through one of three general intervention strategies: externally focused interventions aimed at changing the environment so that the effect of the dysfunction is minimized, internally focused interventions aimed at improving the underlying cognitive ability, and compensatory interventions aimed at teaching children to use alternate strategies that lessen the impact of the dysfunction. This article describes current research involving these approaches for the treatment of attention and memory disorders in children.

Optimizing outcome through cognitive therapy and advocacy: a case study

When the medical model of rehabilitation is used to formulate outcome goals for survivors of traumatic brain injury, pertinent factors weighed typically include premorbid personality and background, current levels of adaptive functioning and physical and neuropsychological impairments. The independent living model utilizes the client's goal and strengths to focus rehabilitation. This case study illustrates how the independent living approach helped a survivor of brain injury achieve his outcome goal; living in his own apartment.

Acquisition of generic memory in amnesia

Amnesic patients' ability to acquire generic, semantic information was assessed relative to their own level of episodic memory. Patients studied a list of words in which some items were presented twice and others once. Upon each presentation, the words were tagged episodically by presenting them in a unique color. Recall of the colors in which words were presented suggested that individual presentations of repeated items were less likely to be recalled than presentations of nonrepeated items; however, actual recall of repeated items exceeded that of nonrepeated items. This outcome demonstrated that amnesics can recall some items generically without recalling either of their individual presentations. However, amnesics' recall of twice-presented items remained far below that of the control group, even when their recall of once-presented items was matched by testing the control group after a delay. This finding suggests that amnesic patients can acquire new generic knowledge but do so much less efficiently than do normal individuals. Furthermore, this deficit occurs independently of the amnesics' episodic memory impairments, reflecting instead a disruption in semantic learning per se.

Transfer of new learning in memory-impaired patients

Previous research has produced conflicting evidence concerning transfer of new learning by amnesic patients. The present experiment investigated the hypothesis that different numbers of learning trials account for differences in transfer, such that the greater the number of repetitions of material in identical stimulus contexts the poorer the transfer. Six memory-impaired patients and six control subjects attempted to learn the names of business-related documents in response to descriptive definitions. Learning continued until one of the following criteria was reached: 50% correct, 100% correct, 100% correct plus 10 trials. In a transfer task, subjects were then asked to produce the target responses to altered definitional cues. The results of the experiment demonstrated that, contrary to prediction, transfer improved with numbers of learning trials. Results are consistent with the view that continued study of information allows better integration of new learning with prior knowledge and correspondingly higher levels of transfer. The theoretical implications of the findings are discussed in terms of the declarative/procedural and the episodic/semantic memory distinction. It is suggested that memory-impaired patients are capable of acquiring new semantic information although not at a normal rate. Implications for memory rehabilitation are also outlined.

Implicit knowledge: new perspectives on unconscious processes

Recent evidence from cognitive science and neuroscience indicates that brain-damaged patients and normal subjects can exhibit nonconscious or implicit knowledge of stimuli that they fail to recollect consciously or perceive explicitly. Dissociations between implicit and explicit knowledge, which have been observed across a variety of domains, tasks, and materials, raise fundamental questions about the nature of perception, memory, and consciousness. This article provides a selective review of relevant evidence and considers such phenomena as priming and implicit memory in amnesic patients and normal subjects, perception without awareness and "blindsight" in patients with damage to visual cortex, and nonconscious recognition of familiar faces in patients with facial-recognition deficits (prosopagnosia). A variety of theoretical approaches to implicit/explicit dissociations are considered. One view is that all of the various dissociations can be attributed to disruption or disconnection of a common mechanism underlying conscious experience; an alternative possibility is that each dissociation requires a separate explanation in terms of domain-specific processes and systems. More generally, it is concluded that rather than reflecting the operation of affectively charged unconscious processes of the kind invoked by psychodynamic or Freudian theorists, dissociations between implicit and explicit knowledge are a natural consequence of the ordinary computations of the brain.

Acquisition and transfer of declarative and procedural knowledge by memory-impaired patients: a computer data-entry task

Previous research demonstrated that a single amnesic patient could acquire complex knowledge and processes required for the performance of a computer data-entry task. The present study extends the earlier work to a larger group of brain-damaged patients with memory disorders of varying severity and of various etiologies and with other accompanying cognitive deficits. All patients were able to learn both the data-entry procedures and the factual information associated with the task. Declarative knowledge was acquired by patients at a much slower rate than normal whereas procedural learning proceeded at approximately the same rate in patients and control subjects. Patients also showed evidence of transfer of declarative knowledge to the procedural task, as well as transfer of the data-entry procedures across changes in materials.

The psychological treatment of memory impairment: a review of empirical studies

Memory impairment is a frequent effect of many different forms of brain dysfunction. Memory impairment is also a frequent focus of treatment interventions, and there have been many different treatment methods suggested. The suggested methods include direct retraining, the use of spared skills in compensating for the impairment (alternate functional systems), and the use of behavioral strategies to circumvent the manifest memory dysfunction (behavioral prosthetics). Unfortunately, there are very few studies comparing the various suggested treatment methods. The present paper evaluates the empirical evidence related to the treatment of memory dysfunction and suggests directions for future investigations. Although the evidence is not conclusive, it appears that some forms of treatment may be helpful in remediating certain types of memory impairment. An approach likely to be productive would include some consideration of the impaired neurological and psychological mechanisms responsible for the manifest memory deficit as well as a consideration of the etiology of the injury thought to be causally related to the memory deficit. As yet, there have been no rigorous empirical evaluations of these considerations.

Interface design as a prosthesis for an individual with a brain injury

This is a case study demonstrating how interface design was applied to make personal productivity software accessible and appropriate for an individual with learning disabilities from a head injury. Substantial customization was required, and nine months of data are presented.

Memory deficit after closed head injury

This paper reviews research concerning impairment of memory during the early and late stages of recovery from closed-head injury (CHI). Posttraumatic and retrograde amnesia are discussed, including direct measurement, rate of forgetting and evoked potential correlates. Studies of residual memory deficit in survivors of CHI are reviewed, including the effects of severity and chronicity of injury and features such as utilization of semantic features to guide recall. The evidence for relatively preserved motor and pattern analyzing skills after severe CHI is presented and the implications for rehabilitation are discussed.

Toward a cognitive neuropsychology of awareness: implicit knowledge and anosognosia

Although a systematic cognitive neuropsychology of awareness has not yet emerged, a number of phenomena reported in the literature provide an empirical basis for developing it. The present discussion focusses on two such phenomena: implicit knowledge, which refers to knowledge that is expressed in task performance unintentionally and with little phenomenal awareness; and anosognosia, which refers to unawareness of neuropsychological deficits. Two types of theoretical accounts of these phenomena are discussed. A first order theoretical account entails postulating damage to, or disconnection of, a system or process that generates awareness across multiple domains. A second-order account does not postulate disruption of a cross-domain awareness mechanism, but instead appeals to difficulties in gaining access to particular kinds of domain-specific information that are associated with aware expressions of knowledge in individual domains. Instances of first- and second-order accounts are illustrated with examples from studies of memory and amnesia. The relation between implicit knowledge and anosognosia is also discussed.

Extending the limits of complex learning in organic amnesia: computer training in a vocational domain

This study explored the limits of learning that could be achieved by an amnesic patient in a complex real-world domain. Using a cuing procedure known as the method of vanishing cues, a severely amnesic encephalitic patient was taught over 250 discrete pieces of new information concerning the rules and procedures for performing a task involving data entry into a computer. Subsequently, she was able to use this acquired knowledge to perform the task accurately and efficiently in the workplace. These results suggest that amnesic patients' preserved learning abilities can be extended well beyond what has been reported previously.