Emanuel Donchin

A Neural System for Error Detection and Compensation

Humans can monitor actions and compensate for errors. Analysis of the human event-related brain potentials (ERPs) accompanying errors provides evidence for a neural process whose activity is specifically associated with monitoring and compensating for erroneous behavior. This error-related activity is enhanced when subjects strive for accurate performance but is diminished when response speed is emphasized at the expense of accuracy. The activity is also related to attempts to compensate for the erroneous behavior.

Guidelines for using human event-related potentials to study cognition: recording standards and publication criteria.

Event-related potentials (ERPs) recorded from the human scalp can provide important information about how the human brain normally processes information and about how this processing may go awry in neurological or psychiatric disorders. Scientists using or studying ERPs must strive to overcome the many technical problems that can occur in the recording and analysis of these potentials. The methods and the results of these ERP studies must be published in a way that allows other scientists to understand exactly what was done so that they can, if necessary, replicate the experiments. The data must then be analyzed and presented in a way that allows different studies to be compared readily. This paper presents guidelines for recording ERPs and criteria for publishing the results.

Brain-computer interface technology: a review of the first international meeting

Over the past decade, many laboratories have begun to explore brain-computer interface (BCI) technology as a radically new communication option for those with neuromuscular impairments that prevent them from using conventional augmentative communication methods. BCIs provide these users with communication channels that do not depend on peripheral nerves and muscles. This article summarizes the first international meeting devoted to BCI research and development. Current BCIs use electroencephalographic (EEG) activity recorded at the scalp or single-unit activity recorded from within cortex to control cursor movement, select letters or icons, or operate a neuroprosthesis. The central element in each BCI is a translation algorithm that converts electrophysiological input from the user into output that controls external devices. BCI operation depends on effective interaction between two adaptive controllers, the user who encodes his or her commands in the electrophysiological input provided to the BCI, and the BCI which recognizes the commands contained in the input and expresses them in device control. Current BCIs have maximum information transfer rates of 5-25 b/min. Achievement of greater speed and accuracy depends on improvements in signal processing, translation algorithms, and user training. These improvements depend on increased interdisciplinary cooperation between neuroscientists, engineers, computer programmers, psychologists, and rehabilitation specialists, and on adoption and widespread application of objective methods for evaluating alternative methods. The practical use of BCI technology depends on the development of appropriate applications, identification of appropriate user groups, and careful attention to the needs and desires of individual users. BCI research and development will also benefit from greater emphasis on peer-reviewed publications, and from adoption of standard venues for presentations and discussion.

A P300-based brain-computer interface : Initial tests by ALS patients

OBJECTIVE The current study evaluates the effectiveness of a brain-computer interface (BCI) system that operates by detecting a P300 elicited by one of four randomly presented stimuli (i.e. YES, NO, PASS, END). METHODS Two groups of participants were tested. The first group included three amyotrophic lateral sclerosis (ALS) patients that varied in degree of disability, but all retained the ability to communicate; the second group included three non-ALS controls. Each participant participated in ten experimental sessions during a period of approximately 6 weeks. During each run the participants task was to attend to one stimulus and disregard the other three. Stimuli were presented auditorily, visually, or in both modes. RESULTS Two of the 3 ALS patients classification rates were equal to those achieved by the non-ALS participants. Waveform morphology varied as a function of the presentation mode, but not in a similar pattern for each participant. CONCLUSIONS The event-related potentials elicited by the target stimuli could be discriminated from the non-target stimuli for the non-ALS and the ALS groups. Future studies will begin to examine online classification. SIGNIFICANCE The results of offline classification suggest that a P300-based BCI can serve as a non-muscular communication device in both ALS, and non-ALS control groups.

The P300 component of the event-related brain potential as an index of information processing

Studies of event-related brain potentials (ERPs) have shown that attributes of the ERP can be used as dependent variables in the study of human information processing. These variables can complement the information gained from the study of overt, skeletal responses. The manner in which the P300 component of the EPR can be used to study human information processing is illustrated in this report. Specifically, we show that through an analysis of the covariation of the latency of P300 component and reaction time, it is possible to examine the relation between the probability of a stimulus and the speed of response to that stimulus. Our data indicate that increased in the probability of a stimulus reduce reaction time by decreasing both stimulus-evaluation and response-production times. We also examine changes in reaction time and P300 latency induced by the match or mismatch between two stimuli presented consecutively, again as a function of probability. Models of the effects of stimulus matching on reaction time are evaluated.

“P300” and memory: Individual differences in the von Restorff effect ☆

Abstract Event-related brain potentials (ERPs) were elicited by words in a free recall paradigm that included a novel item. The P300 component of the ERP is elicited by novel, task-relevant events, and we tested the hypothesis that P300 is a manifestation of the cognitive processing invoked during “context updating.” If the degree to which current representations in working memory need revision is related to P300 amplitude, then the P300 elicited by a given item should be related to the ability to recall that item on a subsequent test. Forty lists were presented to 12 subjects in each of two sessions. The lists were 15 words long, and 1 word, in position 6 through 10, was “isolated” by changing its size. Most subjects recalled these isolated words more often than other words in the same positions (von Restorff effect), and these words also elicited larger P300s than other words. Analysis of variance on the component scores from a principal components analysis revealed that words recalled had a larger amplitude P300 (on initial presentation) than words not recalled. Striking individual differences emerged, and there were strong relationships between the von Restorff effect, overall recall performance, mnemonic strategies, and the association between components of the ERP and recall performance. The overall recall performance of subjects who reported simple (rote) mnemonic strategies was low, but they showed a high von Restorff effect. For these subjects the amplitude of the P300 elicited by words during initial presentation predicted later recall. In contrast, subjects who reported complex mnemonic strategies remembered a high percentage of words and did not show a von Restorff effect. For these subjects P300 did not predict later recall, although a later “slow wave” component of the ERP did. The initial response to isolated items was the same for all subjects (a large P300), and all subjects recognized the isolates faster than other words in a recognition test given at the end of each session. The subjects in whom P300 did not predict recall reported mnemonic strategies that involved organizing the material. These strategies continue long after the time period reflected by P300 (600 msec). Because they were so effective they may have overshadowed the relationship between P300 and recall, which is based on the initial encoding of an event. Our interpretations were further confirmed and clarified from data obtained in a final grand recall and in the recognition test.

Event-related brain potentials: A tool in the study of human information processing

A cognitive psychologist of note who is not particularly impressed with event-related potentials (ERPs) commented recently, while reviewing a grant application, that studies of the behavioral correlates of ERPs can be described as studies in which “phenomena are in search of a theory.” The intent was pejorative, but I found the statement complimentary. I was especially pleased because several years ago in a review of one of my own proposals another referee suggested that in the field of ERPs “one sees a technique futilely searching for phenomena!” We have, it would seem, made good progress in the last decade if we have found phenomena and are now searching for a theory. A detailed review of this progress is presented by Callaway, Tueting, and Koslow (in press).

The event-related brain potential as an index of display-monitoring workload

As an index of task workload, the possible advantages of the event-related brain potential (ERP) over traditional secondary task and physiological measures are described and previous efforts to validate the use of ERPs in this context are discussed. An experiment is then reported in which perceptual load, incurred by monitoring a simulated air-traffic-control display for discrete events, is assessed using (a) measures of the P300 component of ERPs elicited by auditory probe stimuli and (b) a reaction time secondary task. The ERP measures were found to reflect systematically differences in task workload and to covary closely with the reaction time measure. The results are discussed within the framework of a multidimensional conception of human processing resources and task workload.

Averaged evoked potentials and intramodality selective attention

Abstract An attempt was made to determine the effects of attention on average evoked potentials when no general change in the alertness of the subject and when no peripheral gating of sensory inputs can be assumed to operate. Human subjects viewed a 50 msec flash of light superimposed on a fluctuating background ( e.g. , a circle alternating aperiodically with a square). In one of the two experimental conditions, the subject was instructed to ignore the background alternations and to respond to the flash; in the other condition, the subject was required to ignore the flash and to respond to the fluctuations in the background. It was found that the stimulus to which the subject had to respond elicited an AEP with a considerably enhanced late positive component (latency to peak 250–300 msec).

Localization of the event-related potential novelty response as defined by principal components analysis

Recent research indicates that novel stimuli elicit at least two distinct components, the Novelty P3 and the P300. The P300 is thought to be elicited when a context updating mechanism is activated by a wide class of deviant events. The functional significance of the Novelty P3 is uncertain. Identification of the generator sources of the two components could provide additional information about their functional significance. Previous localization efforts have yielded conflicting results. The present report demonstrates that the use of principal components analysis (PCA) results in better convergence with knowledge about functional neuroanatomy than did previous localization efforts. The results are also more convincing than that obtained by two alternative methods, MUSIC-RAP and the Minimum Norm. Source modeling on 129-channel data with BESA and BrainVoyager suggests the P300 has sources in the temporal-parietal junction whereas the Novelty P3 has sources in the anterior cingulate.