Mean response times, variability, and skew in the responding of ADHD children: a response time distributional approach

Response time (RT) distributions from three fixed foreperiod conditions (2, 4, and 8 s) in a warned four-choice RT task were obtained for a group of boys with attention-deficit/hyperactivity disorder, combined type (ADHD; n = 17) and for two groups of normal control boys (age-matched, n = 18, and younger-aged, n = 10). Quantitative measures of distributional shape were derived by fitting the ex-Gaussian distributional model to the individual RT data. Statistical results indicate that the ADHD distributions differ from the age-matched control distributions with respect to the size of the tail (larger for the ADHD boys), but differ from the younger control distributions with respect to the location of the leading edge (slower for the younger control boys). Receiver operating characteristic (ROC) results reveal that the ex-Gaussian exponential component is highly diagnostic of the ADHD boys.     

Some neuropsychological and psychological parameters in children with minimal brain dysfunction: a transcultural comparison

Performances of groups of second grade elementary school boys with Minimal Brain Dysfunction (ns = 34) and matched with normal boys (ns = 30) were studied using mostly psychometric criteria in Prague, Czechoslovakia and Skopje, Macedonia. Boys with brain dysfunctions scored more poorly than normal ones at both places, but normal boys from both cultures did not differ. Information-processing capability (derived from Wechsler scale) was lower and its rank among disordered features higher among Skopje boys, probably because organized care for minimal brain dysfunctioning children was relatively lower.     

Early stimulus processing in dysthymia and anhedonia.

Previous event-related brain potential (ERP) research has found that dysthymic subjects differ from control subjects during later stages of information processing. An important issue that emerges from this literature is whether differences found in these ERP components, typically associated with cognitive processing, can be attributed to earlier differences in basic perceptual processing. This study was undertaken to determine whether early processing deficits are apparent in dysthymic persons. Responses of dysthymics (n = 23) were compared with those of anhedonic (n = 15) and normal control (n = 17) subjects. ERPs were recorded while subjects heard tones at 55, 65, 75, 85, and 95 dB. Overall, N1-P1 and N1-P2 components of the ERP increased in a strong linear fashion as stimulus intensity increased. Dysthymics did exhibit a smaller N1-P2 response than normal subjects, which suggests the presence of difficulties in initial perceptual processing.     

Determinants of associative response latency

The relationship between single-word, free-association response latency and the following characteristics of Kent-Rosanoff words were examined: ( a ) grammatical form class, ( b ) emotionality, ( c ) familiarity, and ( d ) D (the number of different response words given to a stimulus word in a single-word free-association situation by a group of subjects). In addition was examined the relationship between response latency and ( e ) the type of associative linkage constituted by the stimulus-response combination, and ( f ) response frequency. Given the limits posed by the present stimulus material, subject material, and analyses performed, the conclusion was reached that single-word, free-associative response latency is related primarily to D ( r =0.81), secondly to the frequency with which a given stimulus-response combination occurs in a group of subjects.     

Social information processing in child psychiatric populations

This study examined three kinds of social information-processing deficits in child psychiatric populations. The deficits studied were response decision biases, hostile attributional biases, and cue-utilization deficiencies. Subjects were diagnosed as hyperactive/aggressive (H/A) (n=24), exclusively hyperactive (n=14), exclusively aggressive (n=14), psychiatric control (n =23), and normal control (NC) (n=60) boys according to procedures suggested by Loney and Milich (1982). They were administered several tasks to solicit information-processing patterns. The H/A group was found to be deficient in all three areas asssessed, relative to the NC group. They were also deficient in response decisions and cue-utilization, relative to the other three groups of psychiatrically referred boys. Discriminant function analyses demonstrated that the H/A group displayed a distinct processing pattern. These results were found to be relevant to the study of behavior disorders, to social information processing theory, and to intervention efforts with these boys.This work was supported by NIMH Grant No. 32992, awarded to the first author, and NIMH Grant No. 37062, awarded to the second author.     

Effects of exercise intervention on event-related potential and task performance indices of attention networks in children with developmental coordination disorder

The study investigated whether 10-week soccer training can benefit the inhibitory control and neuroelectric indices in children with developmental coordination disorder (DCD). Fifty-one children were divided into groups of typically developing (TD, n=21), DCD-training (n=16), and DCD non-training (n=14) individuals using the for Children test, and, before and after training, were assessed with the visuospatial attention orienting task with their lower extremities, while brain event-related potentials (ERPs) were concurrently recorded. The results indicated that, when compared to TD children, children with DCD responded significantly more slowly across conditions of the visuospatial attention orienting task and showed a deficit of inhibitory control capacity in their lower extremities, whereas no group differences were observed for the accuracy rate. Neuroelectric data indicated that, before training, P3 amplitude was smaller and P3 latency was slower for both DCD groups compared to TD children across conditions of the visuospatial attention orienting task; after training, the beneficial effects were seen in the strength of inhibitory control and P3 latency in the DCD-training group. The data suggest that soccer training resulted in significant improvements in ERP and task performance indices for the children with DCD.     

Inhibition of fear acquisition in toddlers following positive modelling by their mothers

The present study used an experimental design to investigate the role of modelling as a protective factor in fear and avoidance learning in a sample of 77 toddlers. Mothers and their 12-20-month-old children were randomly assigned to one of three pre-exposure conditions: (1) a modelling group (n=27) observed their mothers responding positively to a fear-relevant stimulus; (2) a stimulus-only group (n=25) were exposed to a fear-relevant stimulus alone; and (3) a control group (n=25) were exposed to neither modelling nor the stimulus alone. Children in all three groups were then subjected to an observational conditioning trial in which the experimenter reacted with fear and disgust toward the stimulus. When subsequently tested for the acquisition of fear, children in the modelling group showed more positive affective reactions and more approach behaviours than either controls or children exposed to the stimulus alone. The results demonstrate that very young children can rapidly form lasting associations between maternal affective reactions and novel, fear-relevant stimuli. Further, positive maternal reactions to a stimulus can over-ride any fear-evoking effect of negative reactions to that stimulus by a stranger.     

异同判断中“快同效应”的大脑机制：一项ERP研究

采用高密度的事件相关电位（ERPs）技术,记录分析了大学生被试在执行异同判断任务[包括不同颜色刺激对（DC）,不同形状刺激对（DS）和相同刺激对（Same）]时的脑内时程动态变化。行为结果表明,“同”反应的确显著快于“异”反应,表现出明显的快同效应。ERP结果显示：在280-320 ms内,DS和DC条件均比Same条件诱发一个更负的N2成分。偶极子溯源分析表明,DC和DS条件下,N2可能起源于大脑的前扣带皮层（ACC）,可能与“异”反应早期不一致信息（颜色或形状）的认知监控和调节有关;反之Same条件下,N2成分可能起源于楔前叶,主要反映了“同”反应早期知觉识别中整体特征比较加工的过程（同一性指示器）。另外,在450 ms左右, DC和DS比Same条件均诱发了一个更负的P3成分,可能反映了对刺激局部特征的比较和识别（慢速比较器）,并与选择性注意和资源分配等高级认知活动有关;并且,Same条件下P3成分的潜伏期更短,与行为结果一致。以上研究结果表明,异同判断中“同”反应和“异”反应可能有着不同的比较通道和大脑机制,支持双过程模型理论;同时表明,慢速比较器和同一性指示器可能是序列加工的。     

The temporal selectivity of additive factor effects on the reaction process revealed in ERP component latencies

An experiment was conducted to relate individual components of the event-related brain potential to specific stages of information processing in a two-choice reaction time (RT) task in a group of undergraduate students. Specifically, the latency of the P300 component and the lateralized readiness potential (LRP) were studied as a function of variations in stimulus degradation and response complexity. It was hypothesized that degrading the stimulus would delay the P300 and LRP to the same extent as RT, and that increasing response complexity would affect RT but not P300 latency. The extant literature did not permit any hypothesis regarding the effect of response complexity on LRP latency. The two task variables were found to have additive effects on RT. As predicted, variations in stimulus degradation influenced the latencies of both components, whereas alterations in response complexity had no effect on P300 latency. A significant new finding was that the onset latency of the LRP remained unchanged across levels of response complexity. The overall pattern of results supports the notion of temporal selectivity of stage manipulations that is derived from discrete stage models of human information processing. Furthermore, these results refine the functional interpretation of the LRP by indicating that within the conceptual framework of a stage model the processes this component indexes succeed the start of response choice but precede the start of motor programming.     

Heart rate and visual evoked potentials during figuring arithmetic problems in boys acquired in early childhood with minimal brain damage

Changes of the pattern reversal EP and heart rate (HR) during calculating were studied on 32 boys with minimal brain damage and a control group (n 27) matched in age, sex and intelligence. The introduction of a reference period and repetition of the calculation period should improve the value of all results and should give simultaneously a first insight in the course of the parameters investigated, during mental loading. Both groups reached the same results in calculating, yet only the brain damaged boys simultaneously showed significant longer latencies of the EP. This result was interpreted as an effect of the higher loading of the damaged subjects. The task-depended increase of the HR was significant in both groups. The HR-level was getting lower with the increasing number of brain damage criteria. The results of intercorrelation between in physiologic parameters and datas of subjective feeling and results of calculating was negative in all cases. These findings were interpreted on the basis of several difficulties to find out clear cut patterns of reaction for different clinical groups.     

The Effect of Differential Post-Weaning Environment on the Rigidity of an Animal's Behavior

Seventy-two first, second and third grade boys and girls were administered seriation problems involving different combinations of shape and color variation. Success rates and latency scores were influenced by shape variation, but not by color variation or grade level. The failure to obtain predicted interactions between the effects of grade level and stimulus variation was attributed to the clarity of the relevant stimulus dimension.     

The role of attention in one-handed catching

The present study investigated the contribution of attention to one-handed catching success. A group of skilled (n = 8) and less skilled (n = 9) male subjects were compared in their ability to process secondary task information while executing a primary one-handed catching task. On 40% of the trials, a secondary visual stimulus (SVS) was presented in the peripheral visual field at predetermined times during the flight of the ball. On these trials, the subject was required to complete the one-handed catch and immediately throw the ball at a stationary target. Less skilled subjects made significantly more catching errors under both normal viewing and dual-task processing conditions. The differences were due to errors of positioning rather than grasping. Positioning of the hand appears to require visual attention regardless of skill level, as both skill groups experienced increased difficulty processing secondary task information as the ball approached the catching hand.     

An aggression machine II. Interindividual differences in the aggressive defence responses aroused by varying stimulus conditions

PitkÄnen, L. An aggression machine. II. Interindividual differences in the aggressive defence responses aroused by varying stimulus conditions. Scand. J. Psychol., 1973, 14, 65–74.-The subjects, six aggressive and nonaggressive groups of ten 9-year old boys, selected by rating method, were tested with an "aggression machine" (PAM) constructed by the writer. The varying stimulus conditions included two situations of impulsive aggression and six variations of specified attackers. The results showed that (1) the larger part of the variance of the intensity of aggression in the PAM was accounted for by the situational variations than by interindividual differences in coping with thwarting situations as measured by a rating method. (2) The overtly aggressive boys showed strong discrimination between the situations, while the overtly nonaggressive boys were quite insensitive to situational variations. (3) The intensity of aggressive defence towards a boy of the same age correlated most highly with rated aggressiveness. (4) The latency, duration, and number of aggressive responses did not vary as easily as the intensity according to situations.     

Habituation in normal and Down's syndrome fetuses.

The ability of ten normal and two Down's syndrome fetuses to habituate to a repeated auditory stimulus was assessed. The normal fetuses were assessed on two separate occasions during the final trimester of pregnancy. The number of trials to habituate and latency to respond were recorded. The results demonstrated that all normal fetuses exhibited a decrement in response to repeated presentations of the stimulus, a 250-Hz sine wave. This was the result of habituation and not fatigue since fetuses recovered responding upon presentation of a new (500 Hz) stimulus and habituated faster on re-presentation of the original stimulus. The performance of fetuses remained stable over the two testing periods. The response of the Down's syndrome fetuses was different to that of normal fetuses rarely overlapping indices of habituation exhibited by normal fetuses. The study concludes that habituation may be a powerful tool to examine the behavioural and sensory development of the fetus and may be of use in the antenatal assessment of the existence and severity of neural abnormality.     

Positive facial affect facilitates the identification of famous faces

Several convergent lines of evidence have suggested that the presence of an emotion signal in a visual stimulus can influence processing of that stimulus. In the current study, we picked up on this idea, and explored the hypothesis that the presence of an emotional facial expression (happiness) would facilitate the identification of familiar faces. We studied two groups of normal participants (overall N=54), and neurological patients with either left (n=8) or right (n=10) temporal lobectomies. Reaction times were measured while participants named familiar famous faces that had happy expressions or neutral expressions. In support of the hypothesis, naming was significantly faster for the happy faces, and this effect obtained in the normal participants and in both patient groups. In the patients with left temporal lobectomies, the effect size for this facilitation was large (d=0.87), suggesting that this manipulation might have practical implications for helping such patients compensate for the types of naming defects that often accompany their brain damage. Consistent with other recent work, our findings indicate that emotion can facilitate visual identification, perhaps via a modulatory influence of the amygdala on extrastriate cortex.     

Changes of brain potentials in response to smoking-induced stimuli in smokers.

Changes in P300 amplitude were used as an indicator of reactivity to smoking-related stimuli in smokers. The amplitude of P300--a component of event-related brain potentials (ERPs) elicited by 10 smoking-related (craving), 10 antismoking (aversive) and 10 neutral stimuli-- was recorded in smokers (n=10) and nonsmokers (n=10). Electroencephalography (EEG) data were obtained by the Laxtha EEG-monitoring device in the EEG recording room, and were recorded at F3, F4, C3, and C4. Three-way repeated-measures analysis of variance (ANOVA) was computed on the P300 amplitudes. The factors were group (smokers, nonsmokers), stimulus (craving, aversive, neutral), and electrode location (F3, F4, C3, and C4). The main effects of stimulus were significant, but the group effects did not show significant interactions with other factors. An interesting observation was the similarity between P300 waveforms for craving and aversive stimuli in smokers. These findings could indicate that the antismoking-related response is similar to the smoking-related one.     

Habituation in normal and down's syndrome fetuses

The ability of ten normal and two Down's syndrome fetuses to habituate to a repeated auditory stimulus was assessed. The normal fetuses were assessed on two separate occasions during the final trimester of pregnancy. The number of trials to habituate and latency to respond were recorded. The results demonstrated that all normal fetuses exhibited a decrement in response to repeated presentations of the stimulus, a 250-Hz sine wave. This was the result of habituation and not fatigue since fetuses recovered responding upon presentation of a new (500 Hz) stimulus and habituated faster on re-presentation of the original stimulus. The performance of fetuses remained stable over the two testing periods. The response of the Down's syndrome fetuses was different to that of normal fetuses rarely overlapping indices of habituation exhibited by normal fetuses. The study concludes that habituation may be a powerful tool to examine the behavioural and sensory development of the fetus and may be of use in the antenatal assessment of the existence and severity of neural abnormality.     

Hyperactive and normal children and the error,latency, and double median split scoring procedures of the matching familiar figures test

To further evaluate the construct validity of Kagan's Matching Familiar Figures Test (MFF), three different scoring methods—the MFF error measure, the MFF latency measure, and Kagan's double median split—were used to compare learning disabled and behavior disordered boys at two age levels with their normal peers on the frequency with which they were designated as impulsive. In the comparison of 7-year-old and 12-year-old learning disabled boys with the normal children, the MFF error measure identified a greater frequency of the learning disabled boys as impulsive at both age levels. No differences occurred between the learning disabled and the normal boys at either age level on the latency measure. Kagan's double median split procedure differentiated only between the older learning disabled and the normal boys. Thus, combining the latency measure with the error measure detracted from the effectiveness of the error measure. None of the MFF scoring procedures differentiated between the behavior disordered and the normal boys at either age level. Although the findings tend to support the results of studies with normal children in indicating that the error measure is more sensitive than the latency measure, the failure of the error measure to designate a greater frequency of the severely behavior disordered boys as being impulsive than are their normal peers raises further questions about the construct validity of the MFF, regardless of the scoring procedure used.     

The impact of frontal and non-frontal brain tumor lesions on Wisconsin Card Sorting Test performance

Several lesion and imaging studies have suggested that the Wisconsin Card Sorting Test (WCST) is a measure of executive dysfunction. However, some studies have reported that this measure has poor anatomical specificity because patients with either frontal or non-frontal focal lesions exhibit similar performance. This study examined 25 frontal, 20 non-frontal low-grade brain tumor patients, and 63 normal controls (NC) on the WCST. The frontal patients were also assigned to either a left frontal (n=10) group or a right frontal group (n=15) and compared with the non-frontal group and NC. It was hypothesized that the frontal brain tumor patients would display greater deficits on categories achieved and a higher number of perseverative errors than non-frontal brain tumor patients on the WCST. Finally, it was predicted that right frontal brain tumors would result in greater executive functioning deficits than left frontal or non-frontal brain tumors. Results indicated that the left frontal group achieved the fewest categories and committed the most perseverative errors compared to the other patient and normal control groups. In addition, the left frontal group committed significantly more perseverative errors than the right frontal group. These results suggest that the WCST is sensitive to the effects of low-grade brain tumors on executive functioning.     

Motor and cognitive proficiency of learning disabled and normal children

Motor and cognitive skills of learning disabled (N = 32) and normal (N = 32) boys were compared on the Modified Lincoln-Oseretsky Motor Development Scale and on the WISC-R Vocabulary and Block Design subtests. Eight learning disabled and eight normal boys were tested at four age levels from 8 to 11 years. All boys were of normal intelligence. Motor and cognitive skills of the learning disabled boys were significantly below those of the normal boys and below those of the normative group. Chronological age was not a significant factor in relationship to either motor or cognitive skills. Intercorrelations indicated that in the learning disabled group Block Design, but not Vocabulary, was significantly related to motor scores at the 8- and 9-year ages. These results suggest that a common factor relating to perceptual-motor coordination and efficiency may be involved on the Lincoln-Oseretsky and Block Design subtest for young learning disabled children but not for older learning disabled children or for normal children.