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PubMed2006

Neurocognitive performance and functional disability in the psychosis prodrome.

OBJECTIVE: This study evaluates the pattern of neuropsychological deficits and their association with clinical symptomatology and social functioning in individuals identified as ultra-high-risk (UHR) for psychosis. METHODS: A sample of 45 UHR individuals was identified using the Structured Interview for Prodromal Syndromes (SIPS) from consecutive referrals to the Staglin Music Festival Center for the Assessment and Prevention of Prodromal States (CAPPS) at UCLA. Participants were administered a neurocognitive test battery, as well as measures of global (Strauss-Carpenter Outcome Scale) and social functioning (UCLA Social Attainment Survey). RESULTS: Participants showed significant deficits in speed of processing, verbal learning and memory, and motor speed. Poorer verbal learning and memory performance was significantly associated with poorer social functioning, and there was a trend for poorer performance on reasoning and problem solving to be associated with poorer global functioning. Verbal memory independently predicted social functioning over and above severity of negative symptoms. Cognitive deficits were not associated with severity of clinical symptomatology. CONCLUSIONS: Despite the absence of fully psychotic symptoms, UHR individuals experience significant cognitive deficits, particularly on tasks requiring speeded information-processing and efficient recall from memory, and these deficits appear to be associated with functional disability in a manner parallel to that observed in patients with established psychotic illness.

Adolescent↗

PubMed1997

Aging and counting speed: evidence for process-specific slowing.

The performance of adults ranging in age from 20 to 86 on two nonlexical tasks that required different types of counting operations was examined. Subproportional age effects for incrementing speed and for enumeration speed (counting 5 to 8 items) indicate that some types of counting processes are exempt from the slowing effects of aging. Increased age was associated with a diminished frequency and slowing of subitizing (counting < or = 4 items) as well as with slowing in the speed of initiating the incrementing process, but the course of age-related slowing for these measures is described by different functions. These results indicate that cognitive slowing is not equivalent for different types of processes involved in counting and numerosity judgments.

Adult↗

PubMed2002

Cultural variation in verbal versus spatial neuropsychological function across the life span.

Established culture-invariant measures are needed for cross-cultural assessment of verbal and visuospatial speed of processing and working memory across the life span. In this study, 32 younger and 32 older adults from China and from the United States were administered numerically based and spatially based measures of speed of processing and working memory. Chinese superiority on the numerically based tasks was found for younger adults. Age and increasing task demands diminished this cultural effect, as predicted by the framework proposed by D. C. Park, R. Nisbett, and T. Hedden (1999). However, the visuospatial measures of both working memory and speed of processing did not differ cross-culturally for either age group. The authors concluded that these visuospatial measures provide culture-invariant estimates of cognitive processes in East Asian and Western cultures, but that numerically based tasks show evidence of cultural and linguistic biases in performance levels.

Adult↗

PubMed2006

Control over speeded actions: a common processing locus for micro- and macro-trade-offs?

Cognitive control processes associated with long- and short-term adjustments of human behaviour have attracted much interest recently. It is still unclear, however, whether the mechanisms underlying these adjustments share a common locus within the chain of stimulus-response processing. In order to address this issue, the present study employed a speed-accuracy instruction producing a macro-trade-off, whereas micro-trade-off was studied by means of posterror slowing in reaction time (RT). Participants performed a spatially compatible or incompatible four-stimuli-to-two-response alternative choice RT task. Reliable variations in micro-and macro-trade-off as well as effects of spatial compatibility were found in RT and error rate. Most importantly, posterror slowing was larger when instruction stressed accuracy rather than speed, an effect being independent of spatial compatibility. Because the influence of speed-accuracy instruction and posterror slowing on performance was strongest for response alternations, together present findings suggest that the mechanisms underlying micro- and macro-trade-offs have one common locus at the level of motor processing. Additional influences of macro-trade-off on premotoric processing are likely.

Adolescent↗

PubMed2001

Speed of reaction-transport processes.

We present an approach to determining the speed of wave-front solutions to reaction-transport processes. This method is more accurate than previous ones. This is explicitly shown for several cases of practical interest: (i) the anomalous diffusion reaction, (ii) reaction diffusion in an advective field, and (iii) time-delayed reaction diffusion. There is good agreement with the results of numerical simulations.

Journal Article↗

PubMed2005

Visual speech speeds up the neural processing of auditory speech.

Synchronous presentation of stimuli to the auditory and visual systems can modify the formation of a percept in either modality. For example, perception of auditory speech is improved when the speaker's facial articulatory movements are visible. Neural convergence onto multisensory sites exhibiting supra-additivity has been proposed as the principal mechanism for integration. Recent findings, however, have suggested that putative sensory-specific cortices are responsive to inputs presented through a different modality. Consequently, when and where audiovisual representations emerge remain unsettled. In combined psychophysical and electroencephalography experiments we show that visual speech speeds up the cortical processing of auditory signals early (within 100 ms of signal onset). The auditory-visual interaction is reflected as an articulator-specific temporal facilitation (as well as a nonspecific amplitude reduction). The latency facilitation systematically depends on the degree to which the visual signal predicts possible auditory targets. The observed auditory-visual data support the view that there exist abstract internal representations that constrain the analysis of subsequent speech inputs. This is evidence for the existence of an "analysis-by-synthesis" mechanism in auditory-visual speech perception.

Adult↗

PubMed1987

Age differences in the speed and capacity of information processing: 1. A dual-task approach.

Sixty subjects, spanning the age range from 20 to 65, performed a series of tasks designed to evaluate the effects of aging on the speed and capacity of the human information-processing system. A tracking task was performed alone and concurrently with different versions of a Sternberg memory search task that varied the degree of resource competition with the tracking task. A dichotic-listening task, a tracking-task measure of perceptual-motor speed, and a complex transcription task were also performed. The data revealed a monotonic decrease in processing speed with age but no difference in time-sharing abilities between age groups. The latter conclusion was supported by a factor analysis of the test scores, which revealed that scores on the factor defining time-sharing did not differ with age.

Adult↗

PubMedDate not supplied

[Paroxysmal changes in the electrochemical activity of the cerebral cortex on platinum electrodes].

In rabbits potentials were simultaneously led off from a platinum, a gold and a non-polarizable electrodes (implanted down to the brain surface) by means of a DC amplifier, and under certain conditions changes in the potential of the platinum electrode were recorded which we named "paroxismal changes of bioelectrochemical potential", PBEChP. They had typical parameters: negative sign; speed of process increase considerably exceeding the speed of its decline; amplitude within the range from hundreds of mcV to several mV; duration from fractions of a second to several seconds; high degree of locality (up to 1.5-2 mm2). They revealed a close connection with the background periodic oscillations of the bioelectrochemical potential and were intensified with presentation of different sensory stimuli. It is assumed that PBEChP may be related to some forms of seizure activity.

Animals↗

PubMed2006

The effects of the ACTIVE cognitive training trial on clinically relevant declines in health-related quality of life.

OBJECTIVES: The Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study used three cognitive interventions (memory, reasoning, or speed of processing) in order to improve cognitive abilities. In this article, we evaluate ACTIVE's ability to avoid extensive decline in health-related quality of life (HRQoL). METHODS: ACTIVE enrolled 2,802 adults aged 65 or older and randomized them into one of three cognitive interventions or a no-contact control group. Researchers obtained data on 2,147 participants at the 24-month follow-up. We measured HRQoL by using the eight Short Form-36 scales, and we defined clinically relevant decline on each as a drop of 0.5 standard deviations from baseline. We defined extensive HRQoL decline as clinically relevant drops on four or more Short Form-36 scales, and we assessed this by using multiple logistic regression methods that adjusted for sociodemographic, cognitive, and health status covariates, and incorporated propensity score derived weights in order to adjust for potential attrition bias. RESULTS: We found that 25.0% of ACTIVE participants had extensive HRQoL decline. Participants in the speed-of-processing intervention arm were less likely to have extensive HRQoL decline (adjusted odds ratio = 0.643; p =.004) compared with controls, and participants in the memory and reasoning arms were equivalent to controls (adjusted odds ratios = 1.149 and 1.014, respectively; ps =.322 and.919, respectively). DISCUSSION: Although all three intervention arms improved cognitive ability, only the speed-of-processing arm protected against extensive clinically relevant decline in HRQoL.

Aged↗

PubMed2005

How global versus local perception fits regulatory focus.

We propose a reciprocal relation between regulatory-focus systems and global versus local processing styles-specifically, that global processing fits a promotion focus on advancement, whereas local processing fits a prevention focus on security. In Study 1, participants were shown large letters made of small letters and decided if either of two specific letters appeared on the screen. Strength of promotion focus was positively correlated with speed of processing global letters and negatively correlated with speed of processing local letters, whereas the reverse was true for strength of prevention focus. In Study 2, participants first worked on a global or local task and later chose between two objects. Consistent with our fit proposal, participants who had performed the global task assigned a higher price to their chosen object if they had chosen it in a promotive, eager manner than if they had chosen it in a preventive, vigilant manner, whereas the reverse was true for participants who had performed the local task.

Analysis of Variance↗

PubMed2000

Information processing efficiency in patients with multiple sclerosis.

Reduced information processing efficiency, consequent to impaired neural transmission, has been proposed as underlying various cognitive problems in patients with Multiple Sclerosis (MS). This study employed two measures developed from experimental psychology that control for the potential confound of perceptual-motor abnormalities (Salthouse, Babcock, & Shaw, 1991; Sternberg, 1966, 1969) to assess the speed of information processing and working memory capacity in patients with mild to moderate MS. Although patients had significantly more cognitive complaints than neurologically intact matched controls, their performance on standard tests of immediate memory span did not differ from control participants and their word list learning was within normal limits. On the experimental measures, both relapsing-remitting and secondary-progressive patients exhibited significantly slowed information processing speed relative to controls. However, only the secondary-progressive patients had an additional decrement in working memory capacity. Depression, fatigue, or neurologic disability did not account for performance differences on these measures. While speed of information processing may be slowed early in the disease process, deficits in working memory capacity may appear only as there is progression of MS. It is these latter deficits, however, that may underlie the impairment of new learning that patients with MS demonstrate.

Adult↗

PubMed2000

Changes on the stroop test following treatment: relation to word type, treatment condition, and treatment outcome among women with bulimia nervosa.

OBJECTIVE: To examine changes in speed of information processing on a modification of the Stroop color-naming task following cognitive-behavior therapy (CBT) and to evaluate whether changes are associated with word type, treatment condition, or treatment response. METHOD: Subjects were 98 women aged between 17 and 45 years with a current primary diagnosis of bulimia nervosa who were participating in a randomized clinical trial evaluating CBT. Data were available on all relevant variables for 98 women. Speed of information processing was assessed at pretreatment and posttreatment using a modification of the Stroop color-naming paradigm. RESULTS: Significant main effects were found for the factors time (pretreatment vs. posttreatment) and word type (food/body words vs. color words, food/body words vs. control words). Predicted interactions between time and word type were not identified. DISCUSSION: Changes in information processing speed over treatment were not specifically associated with word type, treatment condition, or treatment response. Consequently, the utility of the modified Stroop paradigm as a measure of change over time for bulimia nervosa is questioned.

Adolescent↗

PubMed1996

The effects of hemispheric asymmetries and depression on the perception of emotion.

The present study investigated hemispheric asymmetries in the perception of positive and negative emotion. The moderating effect of depression on hemispheric asymmetries was also examined. Forty undergraduates were presented with happy and sad faces using a bilateral visual half-field design. Subjects were classified as depressed or nondepressed based on scores on the Beck Depression Inventory. For nondepressed subjects, a right hemisphere advantage emerged for the speed of processing open and close-mouth sad expressions. For depressed subjects a right hemisphere advantage emerged for the speed of processing open-mouth sad expressions. In addition, a right hemisphere advantage for accuracy in identifying sad expressions was found for all subjects. No visual field differences were found for processing happy expressions.

Affect↗

PubMed2005

Understanding the nature of face processing impairment in autism: insights from behavioral and electrophysiological studies.

This article reviews behavioral and electrophysiological studies of face processing and discusses hypotheses for understanding the nature of face processing impairments in autism. Based on results of behavioral studies, this study demonstrates that individuals with autism have impaired face discrimination and recognition and use atypical strategies for processing faces characterized by reduced attention to the eyes and piecemeal rather than configural strategies. Based on results of electrophysiological studies, this article concludes that face processing impairments are present early in autism, by 3 years of age. Such studies have detected abnormalities in both early (N170 reflecting structural encoding) and late (NC reflecting recognition memory) stages of face processing. Event-related potential studies of young children and adults with autism have found slower speed of processing of faces, a failure to show the expected speed advantage of processing faces versus nonface stimuli, and atypical scalp topography suggesting abnormal cortical specialization for face processing. Other electrophysiological studies have suggested that autism is associated with early and late stage processing impairments of facial expressions of emotion (fear) and decreased perceptual binding as reflected in reduced gamma during face processing. This article describes two types of hypotheses-cognitive/perceptual and motivational/affective--that offer frameworks for understanding the nature of face processing impairments in autism. This article discusses implications for intervention.

Autistic Disorder↗

PubMed2000

Cognitive avoidance and bulimic psychopathology: the relevance of temporal factors in a nonclinical population.

OBJECTIVE: Previous research has provided evidence of both an attentional bias towards, and a cognitive avoidance of threat cues, by individuals with unhealthy eating attitudes and disorders. It has been suggested that an initial attentional bias might be followed by a later avoidance process. The present study assessed the speed of processing of self-directed ego threat words following different interstimulus intervals (500, 1,000, 1,500, and 2,000 ms). METHOD: Fifty female students completed a computer-driven threat processing task and the Eating Disorders Inventory. RESULTS: Women were significantly slower to process ego-self threat cues following the 2, 000-ms interval than following the other intervals (500, 1,000, and 1,500 ms). Those women with increased levels of bulimic attitudes were slower to process threats following the 1,500-ms interval, but not after the longer or shorter intervals. CONCLUSIONS: The results stress the importance of temporal factors in the processing of threat by individuals with high levels of eating psychopathology. The findings are discussed in terms of an appropriate cognitive model.

Adult↗

PubMed1999

Reading comprehension and working memory in learning-disabled readers: Is the phonological loop more important than the executive system?

This investigation explores the contribution of two working memory systems (the articulatory loop and the central executive) to the performance differences between learning-disabled (LD) and skilled readers. Performances of LD, chronological age (CA) matched, and reading level-matched children were compared on measures of phonological processing accuracy and speed (articulatory system), long-term memory (LTM) accuracy and speed, and executive processing. The results indicated that (a) LD readers were inferior on measures of articulatory, LTM, and executive processing; (b) LD readers were superior to RL readers on measures of executive processing, but were comparable to RL readers on measures of the articulatory and LTM system; (c) executive processing differences remained significant between LD and CA-matched children when measures of reading comprehension, articulatory processes, and LTM processes were partialed from the analysis; and (d) executive processing contributed significant variance to reading comprehension when measures of the articulatory and LTM systems were entered into a hierarchical regression model. In summary, LD readers experience constraints in the articulatory and LTM system, but constraints mediate only some of the influence of executive processing on reading comprehension. Further, LD readers suffer executive processing problems nonspecific to their reading comprehension problems.

Child↗

PubMed2004

The effects of aging on location-based and distance-based processes in memory for time.

Retrieving when an event occurred may depend on an estimation of the age of the event (distance-based processes) or on strategic reconstruction processes based on contextual information associated with the event (location-based processes). Young and older participants performed a list discrimination task that has been designed to dissociate the contribution of both types of processes. An adapted Remember/Know/Guess procedure [Can. J. Exp. Psychol. 50 (1996) 114] was developed to evaluate the processes used by the participants to recognize the stimuli and retrieve their list of occurrence. The results showed that aging disrupts location-based processes more than distance-based processes. In addition, a limitation of speed of processing and working-memory capacities was the main predictor of age-related differences on location-based processes, whereas working-memory capacities mediated partly age differences on distance-based processes.

Adolescent↗

PubMed2004

Differences in cognitive impairment of relapsing remitting, secondary, and primary progressive MS.

OBJECTIVE: To investigate the cognitive skills of patients with relapsing remitting multiple sclerosis (RRMS), secondary progressive MS (SPMS), and primary progressive MS (PPMS) relative to healthy control subjects and to assess whether there is heterogeneity in the type of cognitive disabilities demonstrated by patients with different MS phenotypes. METHODS: RRMS patients (n = 108), SPMS patients (n = 71), PPMS patients (n = 55), and healthy control subjects (n = 67) underwent neuropsychological assessment with the Brief Repeatable Battery of Neuropsychological Tests. RESULTS: Relative to controls, cognitive performance of RRMS patients was deficient when tasks required higher-order working memory (WM) processes (Word List Generation, 10/36 Spatial Recall Test, Symbol Digit Modalities Test). PPMS and SPMS patients performed poorer than control subjects on all tasks. SPMS patients performed more poorly than PPMS patients when tasks required higher-order WM processes, except when speed of information processing played a relatively important role (Symbol Digit Modalities Test, Paced Auditory Serial Addition Test). Whereas RRMS patients generally performed better than the progressive subtypes, they showed relatively poor verbal fluency. CONCLUSION: MS patients with different disease courses have different cognitive profiles.

Adult↗