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PubMed2003

The difference engine: a model of diversity in speeded cognition.

A theory of diversity in speeded cognition, the difference engine, is proposed, in which information processing is represented as a series of generic computational steps. Some individuals tend to perform all of these computations relatively quickly and other individuals tend to perform them all relatively slowly, reflecting the existence of a general cognitive speed factor, but the time required for response selection and execution is assumed to be independent of cognitive speed. The difference engine correctly predicts the positively accelerated form of the relation between diversity of performance, as measured by the standard deviation for the group, and task difficulty, as indexed by the mean response time (RT) for the group. In addition, the difference engine correctly predicts approximately linear relations between the RTs of any individual and average performance for the group, with the regression lines for fast individuals having slopes less than 1.0 (and positive intercepts) and the regression lines for slow individuals having slopes greater than 1.0 (and negative intercepts). Similar predictions are made for comparisons of slow, average, and fast subgroups, regardless of whether those subgroups are formed on the basis of differences in ability, age, or health status. These predictions are consistent with evidence from studies of healthy young and older adults as well as from studies of depressed and age-matched control groups.

Cognition↗

PubMed2005

The functional significance of mu rhythms: translating "seeing" and "hearing" into "doing".

Existing evidence indicates that mu and other alpha-like rhythms are independent phenomena because of differences in source generation, sensitivity to sensory events, bilateral coherence, frequency, and power. Although mu suppression and enhancement echo sensorimotor processing in frontoparietal networks, they are also sensitive to cognitive and affective influences and likely reflect more than an idling brain state. Mu rhythms are present at early stages of human development and in other mammalian species. They exhibit adaptive and dynamically changing properties, including frequency acceleration and posterior-to-anterior shifts in focus. Furthermore, individuals can learn to control mu rhythms volitionally in a very short period of time. This raises questions about the mu rhythm's open neural architecture and ability to respond to cognitive, affective, and motor imagery, implying an even greater developmental and functional role than has previously been ascribed to it. Recent studies have suggested that mu rhythms reflect downstream modulation of motor cortex by prefrontal mirror neurons, i.e., cells that may play a critical role in imitation learning and the ability to understand the actions of others. It is proposed that mu rhythms represent an important information processing function that links perception and action-specifically, the transformation of "seeing" and "hearing" into "doing." In a broader context, this transformation function results from an entrainment/gating mechanism in which multiple alpha networks (visual-, auditory-, and somatosensory-centered domains), typically producing rhythmic oscillations in a locally independent manner, become coupled and entrained. A global or 'diffuse and distributed alpha system' comes into existence when these independent sources of alpha become coherently engaged in transforming perception to action.

Animals↗

PubMed2002

Diagnostic profile of young and middle-aged memory clinic patients.

With the objective of characterizing the underlying conditions in younger patients with cognitive symptoms, 314 consecutive patients were studied, aged <60 years, referred to a multidisciplinary memory clinic over a period of 54 months. Fifteen percent of the patients fulfilled Diagnostic and Statistical Manual IV criteria for dementia, 17% had selective cognitive deficits, and 55% had no cognitive deficits. Cognitive symptoms in younger patients rarely reflect dementia but more often other medical and psychiatric conditions.

Adolescent↗

PubMed1983

Impulsivity and strategy transfer: metamemory as mediator.

Acquisition, maintenance, and generalization of organizational strategies were studied as a function of impulsivity-reflectivity and metamemory. In Experiment 1, 64 second- and third-grade children, identified as impulsive or reflective, participated in strategy training and transfer sessions; 25 children in a control condition received the same tasks without strategy training. Strategy and metamemory scores were significantly higher for reflective than impulsive children. Metamemory predicted strategic behavior when cognitive tempo was removed. In Experiment 2, 80 children were given an expanded metamemory battery designed to assess verbalized knowledge of memory processes. Children in the experimental condition were trained to use an organizational strategy and later tested for its maintenance and transfer. Strategy scores were higher for the reflective children during transfer but not training, suggesting a relationship between cognitive tempo and the ability to use strategies in new contexts. Reflective children were again found to have higher metamemory scores. The correlation between metamemory and strategy use with cognitive tempo partialed out was significant, whereas the tempo-strategy use correlation was nonsignificant when metamemory was removed. Strategy maintenance and generalization in impulsive and reflective children appear mediated by metamemorial processes.

Child↗

PubMed2002

Dissociation between spontaneous and reactive flexibility in early Parkinson's disease.

OBJECTIVE: This study was designed to examine the relations between the severity of motor symptoms and impaired cognitive flexibility in Parkinson's disease. BACKGROUND: Studies that examine cognitive flexibility in Parkinson's disease report conflicting results. We hypothesized that such inconsistency may reflect a differential pattern of impairment on tasks that measure spontaneous versus reactive flexibility. METHODS: The performance of tasks requiring either spontaneous (Alternate Uses) or reactive (Wisconsin Card Sorting Test) cognitive flexibility was examined in newly diagnosed unmedicated patients with idiopathic Parkinson's disease, as compared with age- and education-matched controls. The correlation between the degree of deficit and severity of motor symptoms was also examined. RESULTS: Patients were significantly worse than controls in performing both types of tasks. The patients' performance on tasks of spontaneous reactivity was not correlated with the presence or severity of the motor signs and symptoms. However, only patients showing signs of bradykinesia were impaired on a measure of reactive cognitive flexibility and the degree of impairment was significantly correlated with the severity of bradykinesia. CONCLUSIONS: These findings suggest that the dissociation between the two types of cognitive flexibility may reflect the differential involvement of the mesocortical and striatonigral dopaminergic circuits in the mediation of these tasks.

Aged↗

PubMed1993

The aging mind: potential and limits.

Research on the aging mind has moved from a simple growth vs decline view to a conception of a joint consideration of potential and limits. This development is illustrated by research on two categories of cognitive functioning: the cognitive mechanics and the cognitive pragmatics. The cognitive mechanics (comparable to fluid intelligence) are primarily determined by the evolution-based neurophysiological architecture of the mind, whereas the cognitive pragmatics (comparable to crystallized intelligence) primarily reflect the impact of culture. Testing-the-limits research on basic memory serves as a prototypical instantiation of the aging of cognitive mechanics; research on wisdom and the cognitive management of the self are prototypical examples of the aging of cognitive pragmatics. In the cognitive mechanics, as one would expect from a phenomenon which is largely genetically and biologically controlled, there is definite aging loss. Conversely, in the cognitive pragmatics, which is primarily culture-based, there is evidence for stability and positive change in persons who reach old age without specific brain pathology, and who live in favorable life circumstances. A model of successful aging, selective optimization with compensation, is presented to illustrate how individuals and societies might effectively manage the age-related shift toward a less positive balance between gains and losses and the associated dynamics between culture-based growth and biology-based decline in level of functioning.

Aged↗

PubMed1998

Cortical dysfunction in schizophrenia during auditory word and tone working memory demonstrated by functional magnetic resonance imaging.

BACKGROUND: Verbal learning and memory deficits are among the most severe cognitive deficits observed in schizophrenia. We have demonstrated that such deficits do not extend to working memory for tones in a substantial number of patients even when verbal working memory is impaired. In this study we used functional magnetic resonance imaging to study the neural basis of this dissociation of auditory verbal and nonverbal working memory in individuals with schizophrenia. METHODS: While undergoing functional magnetic resonance imaging, 12 schizophrenic patients and 12 matched control subjects performed auditory Word Serial Position Task and Tone Serial Position Task. RESULTS: Both tasks produced activation in frontal cortex and temporal and parietal lobes of the cerebrum in both groups. While robust activation was observed in the left inferior frontal gyrus (areas 6, 44, and 45) in the control group during the Word Serial Position Task, activation in the patient group was much reduced in these areas and failed to show the same task-specific activation as in controls. Reduced activation in patients was not confined to the inferior frontal gyrus, but also extended to a medial area during the Tone Serial Position Task and to premotor and anterior temporal lobe areas during both tasks. CONCLUSIONS: These findings support the hypothesis that abnormalities in cortical hemodynamic response in the inferior frontal gyrus underlie the verbal working memory deficit in schizophrenia. The relationship of verbal working memory deficits to other cognitive functions suggests that abnormal functioning in the speech-related areas may reflect a critical substrate of a broad range of cognitive dysfunctions associated with schizophrenia.

Adult↗

PubMed1986

["The screaming baby": Remarks on the article by Mangold and Fuchs ].

Mangold and Fuchs (1986) have pointed out that the topic "Screaming Babies" has only been cursorily addressed in the German literature. Some remarks and elaborations to the theoretical analysis by Mangold anf Fuchs are offered from the perspective of Developmental Psychology and Behavioural Paediatrics. Reviewing the anglo-american literature and our own research it is argued that infants cannot be viewed as "tabula rasa". Instead we conclude that they make a significant contribution to the interactions with the caretaker. It is emphasised that maternal descriptions of infant "difficultness" are reflections of both, infant behaviour and maternal emotional and cognitive state. In the single case we do not know that mother information reflects and we need to employ a multi-method multi-source approach for diagnosis. Finally suggestions for prevention and intervention are outlined based on our experiences in England.

Child Behavior↗

PubMed1989

The effects of d-amphetamine on arousal, cognition, and mood after prolonged total sleep deprivation.

Thirty-six normal male subjects underwent total sleep deprivation for 48 hours, were then administered either placebo, 5, 10, or 20 mg of d-amphetamine, and sleep deprived for an additional 12 hours. Sleep deprivation produced a significant reduction in sleep latency, as well as marked decrements in cognitive performance and self-ratings reflecting vigor and fatigue. Amphetamine reversed these effects in a dose-related way but the pattern and persistence of the reversal varied across measures. After 20 mg, sleep latency normalized for several hours, but then declined. Behavioral effects tended to follow the pattern of sleep latency. On cognitive tasks, 20 mg produced a sustained return to normal performance in an attentional arithmetic task and a gradual improvement in a verbal reasoning task. The partial temporal dissociation among sleep latency, behavioral, and cognitive effects suggests that varying doses of amphetamine may have time-related differential neurochemical effects or that various dimensions of arousal and alertness may be differentially sensitive to amphetamine.

Adult↗

PubMedDate not supplied

Experienced and less-experienced nurses' diagnostic reasoning: implications for fostering students' critical thinking.

PURPOSE: To compare the use of mental representations (heuristics) in diagnostic reasoning of expert (> or = 5 years' experience) and novice (< 5 years' experience) emergency nurses. METHODS: Clinical simulations were completed by a nationwide randomly selected sample of 173 experienced and 46 less-experienced emergency nurses (N = 219). FINDINGS: Experienced nurses used the heuristic, Judging by Causal Systems (diagnostic inferences deduced from systems of causal factors) significantly more did than less-experienced nurses. PRACTICE IMPLICATIONS: Standardized nursing diagnoses may cut short the time needed to develop representational thinking and spare cognitive reserves for reasoning needed for complex patients. Faculty need to promote student's cognitive development through strategies that promote active, reflective, and integrative learning.

Adult↗

PubMed2006

[Ethical aspects of pharmacological cognition enhancement and the use of psychostimulants by children and young persons].

DEFINITION OF THE PROBLEM: Pharmacological cognition enhancement aims at an improvement of cognitive activity and performance in healthy people by means of appropriate drugs. Ethical implications of this kind of cognition enhancement stand in need of reflection. ARGUMENTS: For a number of reasons, the distinction between treatment and enhancement is fuzzy with regard to Attention Deficit Hyperactivity Disorder (ADHD). In consideration of the growing number methylphenidate prescriptions, one question addressed in this article is whether or not psychostimulants are used not only for therapy but also for cognitive enhancement by children and young people. The possibility of a "grey zone" between treatment and enhancement seems to open the field for medicalization of social and pedagogical problems as well as for "hidden enhancement." In clinical practice, the use of stimulants is associated with certain ethical problems concerning diagnosis, treatment and prevention of ADHD. Some of these problems are associated with the possibility of cognition enhancement. In order to evaluate ethical problems of pharmacological cognition enhancement, short-term and long-term consequences of stimulant use need to be taken into account. This refers to the level of transmitter balance in the learning process, to the level of individual learning strategies as well as to the level of interaction. This raises the question (1) of how well adapted the means of enhancement are with regard to the end of a comprehensive education and socialization, and (2) whether there are justifiable limits to the standardization of behavior and knowledge. (3) Moreover, stipulating an autonomous decision as a minimum prerequisite for legitimate cognition enhancement seems inadequate in the case of children and young persons. CONCLUSION: Considering the evidence and the many open questions associated with pharmacological cognition enhancement for children and young persons, it is concluded that it is indeed a morally problematic technique.

Adolescent↗

PubMed2000

A neural basis for general intelligence.

Universal positive correlations between different cognitive tests motivate the concept of "general intelligence" or Spearman's g. Here the neural basis for g is investigated by means of positron emission tomography. Spatial, verbal, and perceptuo-motor tasks with high-g involvement are compared with matched low-g control tasks. In contrast to the common view that g reflects a broad sample of major cognitive functions, high-g tasks do not show diffuse recruitment of multiple brain regions. Instead they are associated with selective recruitment of lateral frontal cortex in one or both hemispheres. Despite very different task content in the three high-g-low-g contrasts, lateral frontal recruitment is markedly similar in each case. Many previous experiments have shown these same frontal regions to be recruited by a broad range of different cognitive demands. The results suggest that "general intelligence" derives from a specific frontal system important in the control of diverse forms of behavior.

Adult↗

PubMed2002

Individual differences in rates of change in cognitive abilities of older persons.

The authors examined change in cognitive abilities in older Catholic clergy members. For up to 6 years, participants underwent annual clinical evaluations, which included a battery of tests from which summary measures of 7 abilities were derived. On average, decline occurred in each ability and was more rapid in older persons than in younger persons. However, wide individual differences were evident at all ages. Rate of change in a given domain was not strongly related to baseline level of function in that domain but was moderately associated with rates of change in other cognitive domains. The results suggest that change in cognitive function in old age primarily reflects person-specific factors rather than an inevitable developmental process.

Aged↗

PubMed1993

Random-number generation and the menstrual cycle: preliminary evidence for a premenstrual alteration of frontal lobe functioning.

20 women (M age = 30.4 yr.) were given the "Mental Dice Task" (randomization of the numbers from 1 to 6) once during the preovulatory and once during the premenstrual phases of their menstrual cycles. In addition, for both test sessions a premenstrual-symptom score was assessed reflecting self-rated severity of cognitive, affective, and somatic complaints during the preovular and the premenstrual phases. In comparison to series of real dice throws, the Mental Dice sequences of all the subjects showed a relative lack of repetitions and an excess of counting at both times of testing. Counting bias was significantly enhanced in the sequences generated during the premenstrual testing and the size of this bias was positively correlated with the self-rated severity of premenstrual symptoms. Pronounced counting despite the instruction to randomize was interpreted as reflecting decreased ability to suppress task-irrelevant cues and indicating a relative impairment of frontal lobe functioning. Resistance of the Mental Dice Task towards expectation biases renders a sociopsychological interpretation of these results improbable. We conjecture that, like other cognitive processes, frontal lobe functions also fluctuate with hormonal changes.

Adult↗

PubMed1990

Clinical and demographic predictors of cognitive performance in multiple sclerosis. Do diagnostic type, disease duration, and disability matter?

Patients with chronic progressive multiple sclerosis often perform more poorly on cognitive tasks than do patients with the relapsing-remitting form of this disease. Whether these differences reflect an independent influence of disease type on cognitive performance is uncertain. We used multiple regression techniques to determine how well performance on a number of tasks done poorly by groups of patients with multiple sclerosis could be predicted by disease type and its confounds: age, disease duration, and disability status as well as other demographic variables. Disease types were assigned longitudinally, based on serial neurological examinations at 6-month intervals over a minimum of 2 years. None of the demographic or clinical variables predicted cognitive performance with more than minimal accuracy. These findings fail to provide support for the assertion that disease type is an important independent determinant of cognitive impairment in multiple sclerosis.

Adult↗

PubMed2006

The future for SNARC could be stark...

The present report by Wood et al. (2006, this issue) invites us to reconsider what we should believe about the cognitive representation of numbers. Researchers interested in numerical cognition have quickly embraced the idea that systematic spatial performance biases in number-related tasks must reflect an inherent spatial attribute of the underlying cognitive representation of numbers. The association between numbers and space (SNARC--spatial numerical association of response codes--effect) has effectively been used to augment the "mental number line" metaphor. Here I discuss the possibility that the SNARC effect is merely an instance of strategic problem solving.

Cognition↗

PubMed1986

The role of defensiveness in cognitive impulsivity.

The role of anxiety in reflection-impulsivity has been a source of controversy, with impulsives portrayed as unanxious by some researchers and as extremely anxious by others. Defensiveness may account for these seemingly contradictory results. Impulsives may present a facade of unconcern to mask underlying anxiety. The impulsive response itself may occur in part because impulsives are defensive about appearing incompetent. Equating rapidity of response with competence, they respond quickly to appear competent. 120 children, with a mean age of 9 years, 7 months, served as subjects. Measurements of defensiveness and impulsivity were examined. Correlations were examined separately by sex since previous research showed that defensiveness correlated negatively with problem-solving success for boys only. Defensiveness and impulsivity were positively correlated for boys only. Unlike previous studies, test anxiety correlated positively with impulsivity for girls.

Anxiety↗

PubMed2006

Mental retardation and relation to seizure and tuber burden in tuberous sclerosis complex.

In patients with tuberous sclerosis complex (TSC), the high rates of mental retardation are associated with cortical tubers, seizure activity, and genetic factors. The goal of the study was to investigate the relationship between bilateral cortical tubers and seizure variables and mental retardation in individuals with TSC. The records of 27 patients with TSC (age 6 months to 33 years) undergoing neuropsychological assessment and the following clinical variables were examined: bilateral versus non-bilateral cortical tubers, the age of seizure onset, and presence of infantile spasms. Results were statistically analyzed. Bilateral cortical tubers (p=0.02) and early age of seizure onset (p=0.04) were significantly related to impaired cognitive functioning. Only one of the seven patients with normal cognitive functioning had bilateral tubers, whereas 13/21 patients with intellectual impairment had bilateral tubers. Patients with normal cognitive functioning experienced a mean age of seizure onset after 6 years. A trend was observed between infantile spasms and cognitive functioning (p=0.06); the lack of statistical significance likely reflects the small sample size. Neither age nor gender was related to cognitive status. Further investigation incorporating additional neuroimaging factors, antiepileptic treatment effects, and genetic variables, is needed.

Adolescent↗