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PubMed1996

Neuropsychological functioning, motor speed, and language processing in boys with and without ADHD.

We administered a neuropsychological battery to boys aged 6 to 12 years old diagnosed with attention-deficit hyperactivity disorder (ADHD; n = 51) and to comparison boys of the same age range (n = 31). Boys with ADHD had greater difficulty than comparison youngsters on nonautomated language and motor tasks administered with a fast instructional set and on one of two traditional frontal executive measures (Porteus mazes). When tasks requiring automatic processing were paired with similar tasks requiring greater use of selective attention processes, the latter, controlled processing tasks differentiated groups better than did automated tasks. This differential effect of otherwise similar tasks is interpreted in terms of an output deficit mediated by response organization as detailed in the information processing literature. The ADHD group also exhibited slow gross motor output, measured independently of verbal output. The findings are evaluated in terms of both Luria's (1973) tripartite model of neurocognitive organization and frontal striatal models, with an emphasis on output processes. The observed language deficits could represent frontal lobe processes intricately related to self-monitoring and planning. The utility of controlled processing, self-paced tasks with fast instructional sets in assessing language and motor skills in ADHD is highlighted.

Analysis of Variance↗
PubMed1991

Perceptual processing and speed-accuracy trade-off.

Three experiments are described on speed-accuracy trade-off during a visual fixation. In a typical trial subjects started by fixating a fixed position at their left side at which a degraded digit (SL) was presented. At about the same time an intact digit (SR) was briefly presented at a fixed right side position. SL and SR were separated by a binocular visual angle of 45 degrees. The task was to verbally report both digits, which implied that the eyes should be rapidly shifted from SL to SR, so as not to miss SR. Under these conditions the distribution of the fixation latencies of SL appeared to consist of two parts, suggesting the occurrence of either anticipations or reactions. This argues against a strategy of optional stopping of information accrual during the fixation of SL and is in line with a strategy of either fully neglecting or fully encoding SL. However, this interpretation meets the difficulty that, at trials where SL is reacted to, subjects showed a shorter fixation latency than in a control condition, in which they had ample time to view both SL and SR. The results of the second and third study supported the view that, when under time stress, subjects can end a fixation as soon as a preliminary code of SL is obtained. This code (a) is insensitive to the complexity of SL, (b) cannot be elaborated during the saccade to SR, and (c) can be used as a starting point for further analysis, as soon as the eyes reach SR.

Achievement↗
PubMed1983

Correlation between reaction time and intelligence in psychometrically similar groups in America and India.

The relationship between psychometrically tested reasoning ability, or general intelligence (Raven's Progressive Matrices), short-term memory (forward and backward digit span), and measures of reaction time (RT), including visual and auditory simple RT and four degrees of choice RT, was investigated in groups of unskilled workers, mostly of below average, borderline, or retarded mental ability, selected in the United States and in India. Both groups showed parallel phenomena with respect to the relative difficulty of the various RT tests, their factor structure, and their theoretically expected correlations with psychometric intelligence, although the correlations were lower (and generally nonsignificant) in the Indian group, most likely because of this group's greater restriction in range of ability. The findings, overall, are consistent with other recent studies of RT and intelligence, which indicate that our standard IQ tests reflect basic cognitive processes, particularly speed of information processing, involved in individual differences in intellectual ability, and not merely differences in specific acquired knowledge, skills, or cultural background.

Adolescent↗
PubMed2007

'Prior entry' for pain: attention speeds the perceptual processing of painful stimuli.

We investigated whether the perception of simultaneity for pairs of nociceptive and visual stimuli was dependent upon the focus of participants' attention to a particular sensory modality (either pain or vision). Two stimuli (one painful and the other visual) were presented randomly at different stimulus onset asynchronies (SOAs) using the method of constant stimuli. Participants made unspeeded verbal responses as to which stimulus they perceived as having been presented first, or else responded that the two stimuli were presented simultaneously. This temporal discrimination task was repeated under three different attention conditions (blocks): divided attention, attend pain, and attend vision. The results showed that under conditions of divided attention, nociceptive stimuli had to be presented before visual stimuli in order for the two to be perceived as simultaneous. A comparison of the two focused attention conditions revealed that the painful stimulus was perceived as occurring earlier in time (relative to the visual stimulus) when attention was directed toward pain than when it was directed toward vision. These results provide the first empirical demonstration that attention can modulate the temporal perception of painful stimuli.

Adult↗
PubMed2003

Event-related potentials and neuropsychological tests in obsessive-compulsive disorder.

OBJECTIVE: Previous studies have provided evidence from event-related potentials (ERPs) and neuropsychological testing of abnormal cognitive processing in obsessive-compulsive disorder (OCD). The aim of this study was to further characterize the cognitive functions of the patients with OCD by utilizing ERPs and neuropsychological tests. METHODS: ERPs were recorded in a group of 31 drug-free OCD patients without depression and 30 normal controls following verbal auditory stimuli using an oddball paradigm. The specific neuropsychological tests administered to assess cognitive functions in all participants were the Stroop Test, Trail Making Test, Design Fluency Test, Controlled Word Association Test (Verbal Fluency test). RESULTS: The patient group showed shorter P300 duration compared to normal controls. In neuropsychological tests, no significant differences were found between the two groups. Negative correlations between Stroop duration and P300 amplitudes in occipital, parietal, and temporal anterior regions were observed. CONCLUSION: Shorter P300 duration may indicate an acceleration in the P300 process, and speeding of cognitive processing, dysfunction of cortico-subcortical circuits, or some combination of all of the above.

Adolescent↗
PubMed1998

Automatic alerting does not speed late motoric processes in a reaction-time task.

When an irrelevant 'accessory' stimulus is presented at about the same time as the imperative signal in a choice reaction time-task, the latency of the voluntary response is markedly reduced. The most prominent cognitive theories agree that this effect is attributable to a brief surge in arousal ('automatic alerting'), but they disagree over whether the facilitation is localized to a late, low-level motoric process or to an earlier stage, the process of orienting to and then perceptually categorizing the reaction stimulus. To test these alternative hypotheses, we used the onset of the lateralized readiness potential (a movement-related brain potential) as a temporal landmark to partition mean reaction time into two time segments. The first segment included the time required to perceive the visual stimulus and decide which hand to react with; the second included only motoric processes. Presentation of an irrelevant acoustic stimulus shortened the first interval but had no effect on the second. We therefore rejected the motoric hypothesis.

Auditory Perception↗
PubMed2005

Some effects of aging on event-related potentials during a linguistic monitoring task.

Two groups of adults, one young and one elderly, were compared on a dichotic task in which continuous speech was monitored for grammatically and semantically anomalous words. Event-related potentials (ERPs) elicited by these anomalies were analyzed in terms of peak amplitude and peak latency of the evoked late-positive component (LPC). Results showed that while LPC peak amplitudes were overall reduced for the group of seniors, LPC peak latencies were similar between both groups of listeners. These findings are consistent with the hypothesis that elderly persons can offset declines in memory, perceptual processes, and speed of mental processing by taking advantage of contextual and prosodic cues in running speech. Additionally, an apparently asymmetric processing negativity was observed in the waveforms of young adults but not seniors. Possible mechanisms include the N400 response to semantic incongruity and a processing negativity component associated with attentional bias toward right hemispace.

Acoustic Stimulation↗
PubMedDate not supplied

Alcohol impairs speed of information processing and simple and choice reaction time and differentially impairs higher-order cognitive abilities.

Previous research has demonstrated that alcohol impairs information processing. However, it is unknown whether this impairment is on all stages of information processing, or on the early, rather than on the later, stages of information processing. Thus, the aim of the present study was to examine the effects of orally administered alcohol on both the early and the later stages of information processing. The present study assessed inspection time (IT), simple reaction time, choice reaction time and cognitive ability (Wechsler Adult Intelligence Scale - Revised) in 16 adult participants in both alcohol and placebo conditions. IT (a measure of the early stages of information processing) was used as a predictor variable in a linear regression to examine whether a disruption of the early stages of information processing accounted for changes in total information processing after alcohol administration. Results indicated that alcohol significantly slowed total information processing, independently of the early stages of information processing.

Adolescent↗
PubMed1997

Speed of mental processing in the middle of the night.

This study aimed to determine whether human mental processing actually slows down during the night hours, separately from the previously documented microsleeps, lapses in attention, and general slowing of motor responses. Eighteen healthy young adults were studied during 36 hours of constant wakeful bedrest. Every 2 hours, they performed a logical reasoning task. Items phrased in the negative voice took reliably longer to respond to than items phrased in the positive voice, indicating the need for more mental processing in those items. By subtracting "negative" from "positive" reaction times at each time of day, we were able to plot a circadian rhythm in the time taken for this extra mental processing to be done separately from microsleeps, psychomotor slowing, and inattention. The extra mental processing took longer at night and on the day following sleep loss than it did during the day before the sleep loss, suggesting that human mental processing slows down during the night under sleep deprivation.

Adult↗
PubMedDate not supplied

Speed of information processing in children referred for learning problems: performance on a visual filtering test.

Children referred for evaluation of learning impairment (LI, N =100) and a comparison group of nonreferred (NLI, N = 243) children were evaluated on a visual filtering task. The task was designed hierarchically to provide for evaluation of component operations-serial search, parallel search, decision, and response. With each additional processing demand, response times increased disproportionately for the LI group relative to the NLI group. Overall response time reliably predicted academic skills and cognitive ability, but was more strongly related to group membership. Thus, this nonverbal visual task is sensitive to a characteristic of children with learning problems over and above discrete academic and cognitive skills. Children with problems adapting to the demands of schooling may be distinguished by a disproportionate vulnerability to processing load.

Child↗
PubMed1985

Adverse neuropsychiatric effects of anticonvulsant drugs.

Clinical and electrical evidence of peripheral neuropathy may result from long term treatment with phenytoin or barbiturates, especially in combination, or after repeated exposure to toxic blood concentrations of either drug. Prolonged acute toxicity with phenytoin may rarely lead to permanent residual ataxia. Reversible dystonia may occasionally be precipitated by phenytoin or carbamazepine; asterixis by phenytoin, barbiturates or carbamazepine; and, more commonly, tremor by valproate. All the major anticonvulsant drugs, especially in combination, can produce occasional subacute cognitive or behavioural syndromes. In varying degrees, the drugs also impair attention, concentration, memory, mental speed or processing, or motor speed. Possible mechanisms of impaired mental function include neuronal damage, or disturbance of folic acid, monoamine or hormonal metabolism. The relative influence on neurological or psychological function is an important factor in the choice of anticonvulsant drug for the treatment of epilepsy.

Animals↗
PubMed2005

Accuracy and speed of orthographic processing in persons with developmental dyslexia.

A group of 39 persons (20 male and 19 female, 11.0 to 32.5 yr.) with developmental dyslexia and 42 controls (21 male and 21 female, 11.2 to 32.3 years) were compared on computerized tests of sight word reading, nonword decoding, and spelling recognition. The subjects with developmental dyslexia performed significantly slower and less accurately than controls on all tasks. Further, the effect size of the group differences was larger for the older group. Within-group analyses showed a significant difference by age group on accuracy. Only the control group showed a significant age difference between groups on response time. Mean accuracy and response times for the reading-disabled subjects resembled shifted versions of the control group means. These results agree with previous reports that phonological deficits persist for reading-disabled adults and suggest a test of whether the discrepancy between reading-disabled and typically achieving readers may actually increase across age groups.

Adolescent↗
PubMed1982

Decelerated synthesized speech as a means of shaping speed of auditory processing of children with delayed language.

This study investigated whether the rate at which children with delayed language process auditory stimuli can be increased through a process of shaping with synthesized speech stimuli. Results indicate that stimuli with slowed down critical formant cues were easier for these 24 children with delayed language to discriminate and that training with stimuli of extended duration did generalize to stimuli of normal durations. Implications of these findings and usefulness of this methodology are discussed.

Child↗