Event-related potentials elicited by automatic targets: a dual-task analysis

The role of limited capacity processes in the detection of automatic targets was investigated in a dual-task paradigm using both behavioral and event-related brain potential (ERP) measures. An automatic detection task was paired with another concurrent discrimination while the relative importance of each task was systematically varied. The resulting performance operating characteristic (POC) showed that both the speed and accuracy of automatic detection responses were affected by the allocation of attention. Reductions in the accuracy of each task were accompanied by reductions in the amplitude of a late-positive component of the ERP (P300). In addition, the latency of the P300 component elicited by automatic targets was increased in dual-task conditions. A comparison of behavioral and ERP measures suggested the involvement of two separate limited-capacity processes in automatic detection: one concerned with the formation of an episodic representation of target occurrence and the other with the execution of rapid motor responses.     

Psychopathy and Event-Related Brain Potentials (ERPs) associated with attention to speech stimuli

Event-related brain potentials (ERPs) were used to determine whether low left-hemisphere arousal or unusual cortical responses to speech stimuli might be associated with anomalies in language function that reportedly occur when psychopaths perform lateralized information-processing tasks. ERPs to phonemic stimuli were recorded while 11 psychopathic (P) and 13 nonpsychopathic (NP) male prison inmates performed a Single-Task and a Dual-Task. In the Single-Task, a speech discrimination ‘oddball’ paradigm, the subject was required to respond whenever a target stimulus (the less frequent of two phonemes) occured. In the Dual-Task, he had to respond to target stimuli while simultaneously performing a perceptual-motor (distractor) task. There were no group differences in ERP measures of central arousal (N100) during performance of the Single- and Dual-Tasks. For both groups, the P300 component of the ERP to the target stimulus was smaller and had longer latency during the Dual-Task than during the Single-Task, indicating that in the Dual-Task phonemic discrimination and the perceptual-motor task completed for similar perceptual resources. Overlapping Group P's P300 responses to the target stimulus during the Dual-Task was a vertex and asymmetric (left-hemisphere) positive slow wave (SW), suggesting unusual speech processing in psychopaths under conditions of distraction, perhaps related to reduced sensitivity to the sequential probabilities associated with events presented in an auditory channel. The results were consistent with the hypothesis that psychopaths have limited left-hemisphere resources for processing linguistic stimuli.     

Event-related potentials, reaction time, and response selection of skilled and less-skilled cricket batsmen

The differences in P300 latency, P300 amplitude, response selection, and reaction time between skilled and less-skilled cricket batsmen have been investigated. Eight skilled and ten less-skilled right-handed batsmen each viewed 100 in-swing, 100 out-swing, and 40 slower deliveries displayed in random sequence from projected video footage whilst their responses and electroencephalograms were recorded. Logistic regression was used to derive a discriminative function for the P300 data. This was done to determine whether the skilled batsmen differed from the less-skilled batsmen on the basis of pooled P300 amplitude and latency data. All the batsmen were correctly characterised as being skilled or less-skilled. Logistic regression equations with reaction time and correctness of response data indicated that behavioural data do not correctly classify skilled performance. It is suggested that skilled cricket batsmen have a superior perceptual decision-making ability compared with less-skilled cricket batsmen, as measured by P300 latency and amplitude. This appears to be the first study showing a link between skill and cerebral cortical activity during a perceptual cricket batting task and it could pave the way for future studies on mental processing in cricket batsmen.     

Temporal discrimination as a function of marker duration

In a series of three experiments, the effect of marker duration on temporal discrimination was evaluated with empty auditory intervals bounded by markers ranging from 3 to 300 msec or presented as a gap within a continuous tone. As a measure of performance, difference thresholds in relation to a base duration of 50 msec were computed. Performance on temporal discrimination was significantly better with markers ranging from 3 to 150 msec than with markers ranging from 225 to 300 msec or under the gap condition. However, within each range of marker duration (3–150 msec; 225–300 msec or gap) performance did not differ significantly. A fourth experiment provided evidence that the effect of marker duration cannot be explained in terms of marker-induced masking. A good approximation of the relationship between marker duration and temporal discrimination performance in the present experiments is a smooth step function, which can account for 99.3% of the variance of mean discrimination performance. Thus, the findings of the present study point to the conclusion that two different mechanisms are used in the processing of temporal information, depending on the duration of the auditory markers. The tradeoff point for the hypothetical shift from one timing mechanism to the other may be found at a marker duration of approximately 200 msec.     

Effects of self-evaluation on the P300 event-related potential

The effects of self evaluation on the P300 event-related potential (ERP) were explored with 56 participants (16 men, 40 women; M age = 23.4 yr., SD = 1.2) across three conditions. The conditions included (1) a standard ERP auditory oddball discrimination between a random target (15% occurrence) and standard stimuli (85% occurrence), (2) the oddball task followed by the additional cognitive task of maintaining a mental count of the target tones, and (3) the oddball task followed by the additional cognitive task of self-evaluating whether they felt surprised by the current occurrence of the target tone. The added cognitive requirements for Conditions 2 and 3 required the subjects to maintain a cognitive readiness for the secondary stimulus-related task during their sensory discrimination response for the standard oddball task. During the self-evaluation condition, the P300 amplitude was significantly larger across all recording locations than the regular oddball condition and the cognitive count condition.     

Tracking the influence of reflexive attention on sensory and cognitive processing

Previously, we demonstrated that reflexive attention facilitates early visual processing during form discrimination (Hopfinger & Mangun, 1998). In the present study, we tested whether reflexive facilitation of early visual processing will be generated when task load is low (simple luminance detection). Target stimuli that were preceded at short cue-to-target intervals by irrelevant visual events (cues) elicited an enhanced sensory (P1) event-related potential (ERP) component as well as an enhanced longer latency, cognitive ERP component (P300). At long cue-to-target intervals, facilitation in these ERP components was no longer observed, and, although inhibition of return (IOR) was observed in reaction times, the ERPs did not show an inhibition of sensory processing. These results provide converging evidence that reflexive attention transiently facilitates neural processing of visual inputs at multiple stages of analysis (i.e., sensory processing and higher order cognitive processing) but question the view that IOR is manifest at the earliest visual cortical stages of analysis.     

The chronometry of mental ability: An event-related potential analysis of an auditory oddball discrimination task

The relation between intelligence and speed of auditory discrimination was investigated during an auditory oddball task with backward masking. In target discrimination conditions that varied in the interval between the target and the masking stimuli and in the tonal frequency of the target and masking stimuli, higher ability participants (HA) displayed more accurate discriminations, faster response time, larger P300 amplitude, and shorter P300 and mismatch negativity (MMN) latency than lower ability participants (LA). Task difficulty effects demonstrated with variation in mask type indicate that the mask does not interfere with the detection of the deviant target stimulus, but rather that the target and mask are integrated as a single compound stimulus. The temporal effects suggest that the speed of accessing short-term memory is faster for HA than LA and, on the basis of the MMN latency, the effect is accomplished automatically, without focused attention. Moreover, the pattern of results obtained with these data support the view that the accuracy effects are determined by processing speed rather than discrimination ability. Comparator models that accommodate these effects are discussed.     

Regional brain activity during face and word discrimination: simultaneous recording of event-related potentials and positron emission tomography

In order to clarify the brain mechanisms involved in the recognition of faces, words, and figures, spatiotemporal analyses were carried out with event-related potentials (ERPs) and positron emission tomography (PET) in normal subjects. In the first experiment, we analyzed the ERPs of eight normal subjects under a passive habituation paradigm using pictures of faces and letters. In the second experiment, regional cerebral blood flow (rCBF) measured using PET was obtained simultaneously with the ERP recordings during a continuous performance task (CPT) in 12 normal subjects. This required the active discrimination of famous people's faces, meaningful words consisting of two Japanese hiragana characters, and simple geometric figures. There were similar deflections in the global field power (GFP) in the first 200 ms of the passive and active tasks, regardless of type of stimuli. This suggests a common time course in the visual information processing mechanisms during the preattentive stage. Mesiotemporal activity, dominant on the right, was seen during the face discrimination task in both the PET results and the ERP topographies. In the word task, activity that was clearly dominant on the left was observed at around a 160 ms latency in the posteriotemporal region of the ERP topography and this again coincided well with the PET data. The spatiotemporal resolution of the analyses was improved by combining PET and topographic ERP studies, and this provided additional neurophysiological information concerning cognitive processing.     

Visual event-related potentials in schizotypal personality disorder and schizophrenia

Schizophrenia (SZ) occurs among a spectrum of disorders with similar characteristics, including schizotypal personality disorder (SPD). Visual processing disturbances have been reported in both disorders, but it is not yet clear which processes are disturbed in both SZ and SPD, suggestive of a common endophenotype, and which appear only in SZ. In order to address this question, the authors evaluated visual event-related potentials (ERPs) elicited during a line-orientation discrimination task in control, SPD, and SZ participants. Visual ERPs allow specification of both the time course and physiological correlates of visual perception and cognition. SZ patients had smaller P100 and P300a amplitudes and prolonged P300b latency compared to the control group. SZ patients also had smaller N160, N200, P300a, and P300b amplitudes compared to the SPD group. SPD participants did not differ from control participants on any ERP measure. These data documented pervasive abnormalities in visual perception and attention in SZ but not in SPD, suggesting that these visual ERP disturbances may not represent a common endophenotype.     

Alcoholism risk and the P300 event-related brain potential: modality, task, and gender effects

The P300 event related potential (ERP) was elicited from young adults at low- (LR) and high-risk (HR) for alcoholism (n = 24/risk group), with equal numbers of male and female subjects employed. The effects of stimulus modality, task difficulty, and gender were assessed with analogous auditory and visual paradigms (tone location/head rotation and tone matching/shape matching). Although task performance was generally comparable across risk groups, LR subjects produced smaller P300 amplitudes than HR subjects for the visual matching tasks. No consistent risk group P300 latency effects were obtained. Gender, task difficulty, and scalp topography differentially modulated the risk group outcomes across paradigms. These findings suggest that P300 amplitude reflects risk-for-alcoholism in male and female young adults, but the specific task conditions and electrode location affect the strength of risk group differences.     

Internal and external control: a two-factor model of amplitude change of event-related potentials

The present paper critically examines the contributions of Event-Related Potential (ERP) measures in mental chronometry research. It is argued that amplitude variations in ERP components may provide valuable information regarding the intensity and timing of information processes, and that these amplitude changes are related to energetical rather than to computational processes. It is also suggested that amplitude variations of ERP components in visual discrimination and selective attention tasks are caused by two different processing modes, denoted as external and internal control that are associated with different neural structures. It is further assumed that these two control systems converge upon thalamic neurons that regulate the sensory input to cortex, and that the direction of sustained ERP amplitude changes reflects which system is dominant. Recent ERP studies have shown that the effects of task variables related to motor control are manifested in a surprisingly early phase of the ERP waveform, and that these effects overlap in time with the effects of task variables related to input control. These findings suggest that at least in visual discrimination and selective attention tasks external and internal modes of processing may be activated in parallel.     

Effect of Acute Psychological Stress on Motion-in-Depth Perception: An Event-Related Potential Study

The present study explored the intrinsic event-related potential (ERP) features of the effects of acute psychological stress on the processing of motion-in-depth perception using a dual-task paradigm. After a mental arithmetic task was used to induce acute psychological stress, a collision task was used to evaluate motion-in-depth perception. The error value and average amplitude of late slow waves (SW) were significantly larger for the earlier colliding spheres’ than for the later colliding spheres. The P1 peak latency in the left occipital region was significantly shorter than that of the right occipital region in the motion-in-depth perception task. Compared to the control condition, the estimated value of residual time-to-collision and error value were significantly reduced, and the N1 peak amplitude and the SW averaged amplitude were significantly increased in the stress condition. Longer motion-in-depth time improved discrimination accuracy and decreased the investment of cognitive resources. Acute psychological stress increased behavioral performance and enhanced attention resources on the motion-in-depth perception task together with greater investment of cognitive resources.     

Effect of memory set-size upon event related potentials for concrete and abstract kanji stimuli.

Event related potentials (ERP) and reaction times (RT) were recorded during the performance of memory-retrieval tasks using the Japanese kanji characters. P300 latency and RT increased as the memory set-size increased. The slope differences between RT and P300 latency were larger for stimuli when concrete kanji were used than when abstract kanji were used. This suggests that, in memory search, the 20 subjects were likely to employ direct lexical access when processing concrete kanji and likely to use phonetic coding when processing abstract kanji.     

Evidence for mental ability related individual differences in the attentional blink obtained by an analysis of the P300 component

Attentional blink (AB) refers to impaired identification of a target (T2) when this target follows a preceding target (T1) after about 150-450 ms within a stream of rapidly presented stimuli. Previous research on a possible relation between AB and mental ability (MA) turned out to be highly ambiguous. The present study investigated MA-related individual differences in consolidation of T2 in working memory during the AB as indicated by the P300 component of the event-related potential. Thirty high (HA) and 30 low MA (LA) female participants performed an AB task while their brain activity was recorded. The AB did not differ between the two groups. HA individuals exhibited a larger P300 amplitude and longer P300 latencies during the AB suggesting higher mental effort. This higher mental effort, however, did not result in better performance presumably because of more competition between target and distractor stimuli in HA than LA individuals.     

The concurrent validity and test–retest reliability of a visuospatial working memory task

To determine whether the visuospatial n-back working memory task is a reliable and valid measure of cognitive processes believed to underlie intelligence, this study compared the reaction times and accuracy of performance of 70 participants, with performance on the Multidimensional Aptitude Battery (MAB). Testing was conducted over two sessions separated by 1 week. Participants completed the MAB during the second test session. Moderate test–retest reliability for percentage accuracy scores was found across the four levels of the n-back task, whilst reaction times were highly reliable. Furthermore, participants' performance on the MAB was negatively correlated with accuracy of performance at the easier levels of the n-back task and positively correlated with accuracy of performance at the harder task levels. These findings confirm previous research examining the cognitive basis of intelligence, and suggest that intelligence is the product of faster speed of information processing, as well as superior working memory capacity.     

Relation between speed of reaction and psychometric tests of mental ability in musculoskeletal injury-prone subjects

Long reaction time (RT), long choice reaction time (CRT), and low scores on psychometric tests of mental ability (MA) have in previous studies been related to musculoskeletal injuries. There has been controversy concerning the relation between slow reaction and low-grade MA recently, the old hypothesis of negative correlation between RT and MA being discussed. The aim of this study was to analyze the relation between speed of reaction and MA. For a sample of 123 volunteer healthy young men simple RT, choice RT, and spatial (block design), verbal and arithmetic components of MA were tested. A principal component analysis was performed and the factor matrix was rotated orthogonally using the varimax method. Two factors were extracted accounting for 73% of the total variance in data space. The mental ability factor, which was responsible for 70% of the variance in factor space, was comprised of components of MA and choice RT. The speed of reaction factor accounted for the remaining 30% of the variance in factor space and was comprised of simple and choice RTs. As choice RT had significant loading on the mental ability factor, the subjects having scores in the lowest quartile on both choice RT and MA total score were compared with the independent expected value by using the chi-squared test. The results of low-grade MA and slow choice reaction were not independent. Accordingly, the results do not support the entire distinction between traditional mental ability or convergent thinking and speed of reaction in normal subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early electro-cortical correlates of inspection time task performance

The concept of general intelligence (g) summarizes the well established finding that scores on separate cognitive tasks are positively correlated, indicating a trait common to many aspects of information processing. Inspection time is a well-established correlate of IQ, where those of a higher IQ can correctly identify a briefly presented stimulus with a greater level of accuracy than those of a lower IQ. This study used two age-matched samples, selected on the basis of their scores on Raven's Advanced Progressive Matrices from the undergraduate population of Bangor University. In order to address the confound of inspection time and IQ of previous ITT-ERP research, each participant of the presented study performed an IT task with the same five levels of stimulus duration while undergoing 64-channel EEG recording. The high IQ group made significantly fewer errors at each level of stimulus duration and exhibited a significantly larger N1 response. N1 latency and other ERP components did not distinguish the two IQ groups. Given the specificity of ERP group differences to the N1, the results of the present study suggest that the link between IT performance and g is attributable to individual differences in directing attention to a spatial region.     

Bottom-up influences on working memory: behavioral and electrophysiological distraction varies with distractor strength

The present study investigates bottom-up effects serving the optimal balance between focusing attention on relevant information and distractibility by potentially significant events outside the focus of attention. We tested whether distraction, indicated by behavioral and event-related brain potential (ERP) measures, varies with the strength of task-irrelevant deviances. Twenty subjects performed a tone-duration discrimination task (200 or 400 ms sinusoidal tones presented equiprobably). The stimuli were presented with frequent standard (p = 0.84; 1000 Hz) or infrequent deviant (p = 0.16) pitch. These task-irrelevant pitch changes consisted in a frequency increase/decrease of 1%, 3%, 5%, or 10%. Each of them resulted in prolonged reaction times (RT) in the duration discrimination task and elicited the MMN, P3a, and RON components of the ERP. Importantly, these measures did increase as a function of pitch deviance. Separating the individual trials on the 1% deviation level into trials with and without RT prolongation, i.e., behavioral distraction effect, revealed that both subgroups had similar MMN, but P3a and RON were confined to the trials with RT prolongation. Results are interpreted within a model relating preattentive deviance detection, distraction, and working memory.     

A developmental investigation of ERP auditory rhyming effects

In a simple auditory rhyming paradigm requiring a button–press response (rhyme/nonrhyme) to the second word (target) of each spoken stimulus pair, both the early (P50, N120, P200, N240) and late (CNV, N400, P300) components of the ERP waveform evidenced considerable change from middle childhood to adulthood. In addition, behavioral accuracy and reaction time improved with increasing age. In contrast, the size, distribution and latency of each of several rhyming effects (including the posterior N400 rhyming effect, a left hemisphere anterior rhyming effect, and early rhyming effects on P50 latency, N120 latency and P200 amplitude) remained constant from age 7 to adulthood. These results indicate that the neurocognitive networks involved in processing auditory rhyme information, as indexed by the present task, are well established and have an adult–like organization at least by the age of 7.     

智力与心理速度的关系研究述评

目前在智力研究领域出现了一种新的研究趋势,研究者开始关注心理计量学智力与认知或生理心理学变量的相关,考察的重点是心理速度,相应的测量指标主要有检测时（IT）、反应时、ERP或神经传导速度,等等。在运用IT任务进行的ERP研究中发现,ERP波幅和潜伏期的不同往往能够反映出智力上的差异。信息加工速度和神经传导速度均与一般智力因素（g因素）存在较高的相关。上述研究发现促进了智力与心理速度关系的跨学科研究,成为智力研究领域中的热点