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PubMed2002

The development of mental processing: efficiency, working memory, and thinking.

This Monograph aims to contribute to the information processing, the differential, and the developmental modeling of the mind, and to work these into an integrated theory. Toward this aim, a longitudinal study is presented that investigates the relations between processing efficiency, working memory, and problem solving from the age of 8 years to to the age of 16 years. The study involved 113 participants, about equally drawn among 8-, 10-, 12-, and 14-year-olds at the first testing; these participants were tested two more times spaced one year apart. Participants were tested with a large array of tasks addressed to processing efficiency (i.e., speed of processing and inhibition), working memory (in terms of Baddeley's model, phonological storage, visual storage, and the central executive of working memory), and problem solving (quantitative, spatial, and verbal reasoning). Confirmatory factor analysis validated the presence of each of the above dimensions and indicated that they are organized in a three-stratum hierarchy. The first stratum includes all of the individual dimensions mentioned above. These dimensions are organized, at the second stratum, in three constructs: processing efficiency, working memory, and problem solving. Finally, all second-order constructs are strongly related to a third-order general factor. This structure was stable in time. Structural equation modeling indicated that the various dimensions are interrelated in a cascade fashion so that more fundamental dimensions are part of more complex dimensions. That is, speed of processing is the most important aspect of processing efficiency, and it perfectly relates to the condition of inhibition, indicating that the more efficient one is in stimulus encoding and identification, the more efficient one is in inhibition. In turn, processing efficiency is strongly related to the condition of executive processes in working memory, which, in turn, is related to the condition of the two modality-specific stores (phonological and visual). Finally, problem solving is related to processing efficiency and working memory, the central executive in particular. All dimensions appear to change systematically with time. Growth modeling suggested that there are significant individual differences in attainment in each of the three aspects of the mind investigated. Moreover, each of the three aspects of the mind as well as their interrelations change differently during development. Mixture growth modeling suggested that there are four types of developing persons, each defined by a different combination of performance in these aspects of the mind. Some types are more efficient and stable developers than others. These analyses indicated that processing efficiency is a factor closely associated with developmental differences in problem solving, whereas working memory is associated with individual differences. Modeling by logistic equations uncovered the rates and form of change in the various dimensions and their reciprocal interactions during development. These findings are discussed from the point of view of information processing, differential, and developmental models of thinking, and an integrative model is proposed.

Age Factors↗
PubMed2004

Neural processing at the speed of smell.

Olfaction is typically described as behaviorally slow, suggesting neural processes on the order of hundreds of milliseconds to seconds as candidate mechanisms in the creation of olfactory percepts. Whereas a recent study challenged this view in suggesting that a single sniff was sufficient for optimal olfactory discrimination, a study by Abraham et al. in this issue of Neuron sets out to negate the challenge by demonstrating increased processing time for discrimination of similar versus dissimilar stimuli. Here we reconcile both studies, which in our view together support the notion of a speed-accuracy tradeoff in olfactory discriminations that are made within about 200 ms. These findings are discussed in light of the challenges related to defining olfactory perceptual similarity in nonhuman animals.

Animals↗
PubMed1988

Aging and visual information processing: potential implications for everyday seeing.

A review of research examining the effects of aging on visual perception from the perspective of psychological theories of information processing shows that the average speed of processing for groups of older adults is slower than for groups of young adults in most stages of perceptual processes. However, studies examining the correlation of processing speed between separate stages within individuals shows little evidence of general slowing in the nervous systems of individual elderly subjects. The implications of performance decrements at each stage of visual processing are considered for a variety of everyday seeing activities. It is concluded that age-related decrements in visual selective attention processes offer the greatest threat of impairment to many everyday seeing activities.

Aged↗
PubMed1989

Attention deficit disorder with and without hyperactivity: reaction time and speed of cognitive processing.

This study addressed the issue as to whether children reliably diagnosed as attention deficit disordered with hyperactivity (ADD/H) and without hyperactivity (ADD/WO) differed significantly from each other and a clinic control (CC) population on speed and efficiency of cognitive processing. From an outpatient clinic population, 43 ADD/H and 22 ADD/WO children were examined. An analysis of mean reaction time and speeded classification task performance revealed significant group effects on both mean reaction time and on a measure of within-subject variability. ADD/H children performed significantly more slowly and variably than the CC children on several of the speeded classification tasks. However, the ADD/WO group was not distinguished on any measure. Thus, while children may be reliably diagnosed as ADD/H or ADD/WO using behavioral measures, it would appear that they cannot be distinguished on these neurocognitive tasks. Issues related to childhood psychopathology and the neuropsychological basis of ADD/H are discussed.

Age Factors↗
PubMed1990

Leuko-araiosis on magnetic resonance imaging and speed of mental processing.

The clinical significance of white matter abnormalities seen in brain imaging studies, termed leuko-araiosis (LA), still remains uncertain. Leuko-araiosis has been associated with a global decline in cognitive performance, although little is known about the cognitive functions that LA may account for. We present the correlates between LA severity on magnetic resonance imaging and mental deterioration in a selected sample of 41 elderly patients with vascular risk factors. We found that LA was related to performance on tasks measuring the speed of information processing and, in particular, on those that involve complex processes. This impairment can be important in producing reduction in daily living activities as it is in the support to the relationship found with some commonly used behavioral rating scales. Leuko-araiosis is also related to the presence of some primitive reflexes, suggesting that their disinhibition may be due to diffuse corticofugal fibers damage.

Aged↗
PubMed1996

Recovery of speed of information processing in closed-head-injury patients.

After severe traumatic brain injury, patients almost invariably demonstrate a slowing of reaction time, reflecting a slowing of central information processing. Methodological problems associated with the traditional method for the analysis of longitudinal data (MANOVA) severely complicate studies on cognitive recovery. It is argued that multilevel models are often better suited for the analysis of improvement over time in clinical settings. Multilevel models take into account individual differences in both overall performance level and recovery. These models enable individual predictions for the recovery of speed of information processing. Recovery is modelled in a group of closed-head-injury patients (N = 24). Recovery was predicted by age and severity of injury, as indicated by coma duration. Over a period up to 44 months post trauma, reaction times were found to decrease faster for patients with longer coma duration.

Adolescent↗
PubMed1999

Executive functions and speed of mental processing in elderly patients with frontal or nonfrontal ischemic stroke.

Impairments in executive functions have been related to aging and frontal lobe lesions. Aging also causes slowing of mental processing. We examined whether ischemic stroke in the frontal brain area results in dysexecutive syndrome, or whether the frontal stroke causes increased slowing of mental processing. Neurological, radiological and neuropsychological examinations were carried out 3 months post-stroke on 250 ischemic stroke patients (55-85 years) and on 39 healthy control subjects. Of the patients, 62 had frontal and 188 had nonfrontal lesions. The neuropsychological examination comprised several cognitive domains, including tests considered to measure executive functions. The frontal group was slower than the nonfrontal group in tasks measuring speed of mental processing which were time-limited (Trail Making A, Stroop dots and fluency). They were also inferior in the Digit Span backwards task. There were no differences between the groups in other cognitive domains, nor in some tests which are considered to be measures of executive functions (e.g. WCST). Impairments in executive functions were evident in both the frontal and the nonfrontal groups compared with the controls, but no dysexecutive syndrome specifically related to frontal lesions was found. Frontal stroke related mainly to the slowing of mental processing.

Age Factors↗
PubMed1989

Social interaction and speed of information processing following very severe head-injury.

Eighteen adults who had suffered a very severe closed head-injury more than 18 months previously and required long-term rehabilitative support were compared with a closely matched control group. Unlike previous studies, which have reported negative personality change involving an increase in aversive behaviour, our behavioural observation data suggest that a global reduction in behavioural productivity, or negative symptomatology, characterizes social interaction by this group. This resulted in their being judged less socially skilled, less likeable and less interesting, and thus less reinforcing to interact with. Speed of information processing was specifically impaired for the closed head-injury group, although this did not correlate with global behavioural ratings of social interaction behaviour. It is suggested that low behavioural productivity may be associated with family burden, and that the low quantity of social interaction experienced by severely head-injured adults may reflect the unreinforcing nature of their interactions.

Adult↗
PubMed1998

[Speed of information processing and fluid intelligence in advanced age. A secondary analysis of data of the Bonn Longitudinal Study of Aging based on "latent growth curve models"].

According to the "speed"-hypothesis of cognitive development, the slowing of information processing in old age is at the core of negative age differences in psychometric intelligence. The present study investigates the "speed"-hypothesis for fluid intelligence at the individual level using Latent Growth Curve Methodology. Data on 4 measurement points come from the Bonn Longitudinal Study of aging (N = 127, mean age 67.2, 53% women). Based on principal factor analysis, markers of mental speed were the WAIS Digit Symbol Test and a simple psychomotor task. As indicators of fluid intelligence the WAIS Object Assembly and Block Design were used. After separately fitting Latent Growth Curve Models for the trajectory of mental speed and fluid intelligence, a combined model showed no statistically significant improvement of fit for freeing the covariance between the two slope-factors. Interpreting this result, contrary to the "speed"-hypothesis the intraindividual change of fluid intelligence does not relate to the according change of mental speed.

Aged↗
PubMed1998

Slowed information processing in HIV-1 disease. The Multicenter AIDS Cohort Study (MACS).

This investigation examined the effects of HIV-1 infection on speeded complex cognitive processing in a group of HIV-negative (n = 666), HIV-positive symptomatic (n = 156), and HIV-positive asymptomatic (n = 623) participants while controlling for the effects of slowed motor functioning, peripheral neuropathy, and several other putative confounds. Stroop Interference and reaction-time tasks served as anchor procedures to assess cognitive processing. The present findings suggest that HIV-1 infection is capable of compromising CNS-mediated cognitive processes (speeded processing) infringing upon their efficacy in the symptomatic stages of the disease while sparing individuals in the asymptomatic stage. The detrimental effects observed on information-processing mechanisms associated with HIV infection persisted despite the use of procedures to control for peripheral nerve integrity and other potential confounds.

AIDS Dementia Complex↗
PubMed2003

Speed of phonological and orthographic processing as factors in dyslexia: electrophysiological evidence.

The author investigated the hypothesis that speed of processing in the phonological and orthographic systems is one of the underlying variables of word-reading effectiveness. Speed of processing was assessed using measures of behavioral reaction time and electrophysiological latencies during phonological and orthographic task performance. Participants were 20 dyslexic and 20 normal-reading, male college students. An electrophysiological component complex (N1-P2-N2), as well as 2 other components (P3 and N4), was identified in both groups on each of the experimental tasks. Significant group differences were obtained only on the phonological tasks. Speed of processing during phonological judgment tasks was significantly prolonged among the dyslexic readers compared with the controls as reflected by P2, P3, and N4 latencies and reaction time. Between-task comparisons revealed significantly prolonged P2, P3, and N4 latencies on phonological compared with orthographic tasks in both dyslexic and normal readers, indicating that phonological classification of words may demand more time than orthographic classification. However, the gap score between speed of processing on the phonological and orthographic tasks was larger among the dyslexic readers and was observed mainly in P3 latency and reaction time. The highest correlation between word-reading accuracy score and the experimental measures was obtained in the dyslexic group with P3 latency gap score and in the control group with P2 latency gap score. The author proposes that slow phonological processing may cause "asynchrony" between the processing speeds within and between phonological and orthographic systems and may lead to a lack of efficient integration among the various subprocesses activated in reading, may slow down reading rate, and may impair word-reading effectiveness.

Adult↗
PubMed2001

Cognitive function in fibromyalgia patients.

OBJECTIVE: To evaluate fibromyalgia (FM) patients for the presence of cognitive deficits and to test the hypothesis that abnormalities would fit a model of cognitive aging. METHODS: We studied 3 groups of patients: FM patients without concomitant depression and in the absence of medications known to affect cognitive function (n = 23), age- and education-matched controls (n = 23), and education-matched older controls who were individually matched to be 20 years older (+/- 3 years) than the FM patients (n = 22). We measured speed of information processing, working memory function, free recall, recognition memory, verbal fluency, and vocabulary. We correlated performance on cognitive tasks with FM symptoms, including depression, anxiety, pain, and fatigue. We also determined if memory complaints were correlated with cognitive performance. RESULTS: As expected, older controls performed more poorly than younger controls on speed of processing, working memory, free recall, and verbal fluency. FM patients performed more poorly than age-matched controls on all measures, with the exception of processing speed. FM patients performed much like older controls, except that they showed better speed of processing and poorer vocabulary. Impaired cognitive performance in FM patients correlated with pain complaints, but not with depressive or anxiety symptoms. FM patients reported more memory problems than did the older and younger controls, and these complaints correlated with poor cognitive performance. CONCLUSION: Cognitive impairment in FM patients, particularly memory and vocabulary deficits, are documented in the study. Nevertheless, the intact performance on measures of information processing speed suggests that the cognitive deficits are not global. FM patients' complaints about their memory are likely to be legitimate, since their memory function is not age appropriate.

Aged↗
PubMed1998

Neuropsychological complications of IDDM in children 2 years after disease onset.

OBJECTIVE: To compare the neuropsychological profiles of children with IDDM with a community control group at two time points: 3 months after disease onset and 2 years after the baseline assessment. RESEARCH DESIGN AND METHODS: A total of 123 children (age 3-14 years) with recent IDDM onset were compared with 129 community control subjects, stratified for age and sex, on standardized measures of general intelligence, attention, speed of processing, memory, learning, executive skills, and behavioral adjustment soon after diagnosis and 2 years later. Exclusion criteria were premorbid evidence of central nervous system disease or trauma, or English not spoken in the home. RESULTS: There were no differences between children with IDDM and control subjects on any measure at the initial assessment 3 months after disease onset. Two years later, children with IDDM tended to show a less positive change, relative to control subjects, in their standardized scores on measures of general intelligence, and significantly so on the vocabulary (P < 0.01) and block design (P < 0.05) subtests. Multivariate group differences were also apparent on speed of processing (P < 0.05) and learning (P < 0.01) subtests, reflecting smaller developmental gains in the children with IDDM when compared with control subjects. CONCLUSIONS: The findings are consistent with previous reports, suggesting that IDDM is associated with an increased risk of mild neuropsychological dysfunction. The skills most affected in this cohort were information processing speed, acquisition of new knowledge, and conceptual reasoning abilities. Clinicians and educators should be made aware of the risk of specific neuropsychological deficits in children with IDDM.

Adolescent↗
PubMed1988

Developmental functions for speeds of cognitive processes.

In Experiment 1, 8- to 21-year-olds were tested on a visual search task in which they determined whether a target digit was present in a set of one to five digits and a memory search task in which they determined whether a target digit was a member of a previously presented set of one to five digits. Increases with age in speeds of visual and memory search were both described well by exponential functions, and the rate of developmental change was similar for the two processes. In Experiment 2, 8- to 22-year-olds were tested on a memory search task, a mental rotation task in which they judged whether a stimulus presented in various orientations was a letter or a mirror image of a letter, an analogical reasoning task in which they judged whether sets of pictures were related to one another according to the same rule, and a mental addition task in which they judged the accuracy of problems such as 2 + 3 = 6. Here, too, for three of the four tasks developmental change was described well by exponential functions with a common rate of change. Results are interpreted in terms of a central mechanism that limits speeded performance and that changes with age.

Adolescent↗
PubMed2000

Shifts in information processing level: the speed theory of intelligence revisited.

A hypothesis is proposed here to reconcile the inconsistencies observed in the IQ-P3 latency relation. The hypothesis stems from the observation that task-induced increase in P3 latency correlates positively with IQ scores. It is hypothesised that: (a) there are several parallel information processing pathways of varying complexity which are associated with the generation of P3 waves of varying latencies; (b) with increasing workload, there is a shift in the 'information processing level' through progressive recruitment of more complex polysynaptic pathways with greater processing power and inhibition of the oligosynaptic pathways; (c) high-IQ subjects have a greater reserve of higher level processing pathways; (d) a given 'task-load' imposes a greater 'mental workload' in subjects with lower IQ than in those with higher IQ. According to this hypothesis, a meaningful comparison of the P3 correlates of IQ is possible only when the information processing level is pushed to its limits.

Humans↗
PubMed2003

The interaction between phonological processing, syntactic awareness, and naming speed in the reading and spelling performance of first-grade children.

The performance of 267 first-grade children was examined on tasks assessing phonological processing, syntactic awareness, and naming speed. The children were also given several measures of word and pseudoword reading, reading comprehension, and pseudoword and dictation spelling. A series of hierarchical analyses indicated that three variables (phonological awareness, syntactic awareness, and naming speed) were still predictors of reading and spelling performance after variance in the others had been controlled for. The results, which confirm that syntactic awareness can account for variance in written language after phonological ability had been controlled for, support the hypothesis concerning the relationships between naming-speed processes and written language, and challenge the unitary phonological theory of reading difficulty.

Awareness↗
PubMed2002

Remediation of "working attention" in mild traumatic brain injury.

Several studies have reported beneficial effects of treatments for attentional deficits following traumatic brain injury. Improvements in speed of processing appear to be less robust than improvements on non-speeded tasks, while several studies suggest greater benefits of training more complex forms of attention. The present study presents preliminary results concerning the effectiveness of an intervention for attentional deficits after mild traumatic brain injury. The treatment was based upon the conceptualization of deficits and interventions as a function of the central executive component of working memory, or "working attention" . A prospective, case-comparison design was employed comparing four treatment participants with an untreated comparison sample. Treatment tasks were derived from experimental procedures which have been demonstrated to elicit working memory demands, consisting of "n-back", random generation, and dual-task procedures. The intervention emphasized the conscious and deliberate use of strategies to effectively allocate attentional resources and manage the rate of information during task performance. Treatment participants were more likely to exhibit clinically significant improvement on measures of attention and reduction of self-reported attentional difficulties in their daily functioning. Further analysis suggested that the principal effect of the intervention was on working memory, i.e. the ability to temporarily maintain and manipulate information during task performance, with no direct effect on processing speed. The results are consistent with a strategy training model of remediation, in which the benefits of treatment are due to participants' improved ability to compensate for residual deficits and adopt strategies for the more effective allocation of their remaining attentional resources.

Adult↗