[How does the brain react to conflict and error?].
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Attention↗
Biomedical subjects
M Falkenstein
Publications and source records attributed to M Falkenstein.
Effects of stimulus-response compatibility in Parkinson's disease: a psychophysiological analysis.
The present study investigated the mechanisms underlying stimulus-response compatibility effects in Parkinson's disease patients and matched controls. Since basal ganglia are involved in the selection and inhibition of competing responses we examined whether basal ganglia dysfunction in Parkinson's disease leads to greater interference effects compared to the control subjects. Reaction times and lateralized movement-related cortical potentials (lateralized readiness potential: LRP) were recorded in two modified Eriksen flanker tasks. Both groups were influenced by compatibility conditions; interference was seen as enhanced reaction time and error rate, as well as incorrect early LRP and delayed late LRP in incongruent trials. Altogether, behavioral and electrophysiological measures showed the interference to be rather smaller for the patients than for the controls. In contrast, facilitation did not differ among groups. Hence the claim that Parkinson's disease patients are more influenced than controls by interfering directional stimuli appears not always valid.
Electroencephalography↗
Auditory distraction in young and middle-aged adults: a behavioural and event-related potential study.
Cognitive tasks involving distraction are associated with an early age-related decline in performance. Involuntary shifts in attention to irrelevant stimulus features and subsequent reorientation were studied in young and middle-aged subjects focussing on behavioural and event-related potential (ERP) measures. Subjects were asked to discriminate between equiprobable short and long auditory stimuli. Irrelevant rare frequency deviations prolonged reaction times (RT's), while an age-related effect on RT's was not observed. In contrast, notably after short deviant tones the error rate was considerably increased in the middle-aged subjects. ERP measures after deviant stimuli elicited a sequence of mismatch negativity (MMN), P3a and reorienting negativity (RON). The latency and amplitude of the MMN did not differ between age groups indicating an unchanged deviance detection. However, the consecutive process of attention orientation (P3a) was delayed and the subsequent reorienting (RON) to the primary task was strongly attenuated in the middle-aged subjects. After short deviants the RON was virtually absent in the middle-aged subjects, which might account for the observed decline of accuracy.
Acoustic Stimulation↗
Action monitoring, error detection, and the basal ganglia: an ERP study.
The error negativity (Ne or ERN) is an event-related brain potential component, which is assumed to reflect error detection. Recently it has been hypothesized that the basal ganglia are assumed to play a crucial role in error detection. In the present study we ask whether the Ne is altered in patients with Parkinson's disease (PD), who have an impaired function of the basal ganglia. We recorded the Ne in patients and in matched controls, while they performed different tasks that require a relatively high cognitive control, which is supposed to pose particular problems on PD. The Ne was in fact smaller in the patients than in the controls in all tasks. Our results suggest an impairment of error detection in PD for different types of demanding tasks. This supports the hypothesis that the basal ganglia do play an important role for error detection in action monitoring.
Aged↗
Changes of error-related ERPs with age.
Errors in reaction tasks are followed by a negative component of the event-related brain potential (ERP), the error negativity (Ne), which is thought to be a correlate of error detection. In the present study we show that, in tasks that induce different types of errors, the amplitude of the Ne was reduced in elderly (54-65 years old) compared with young subjects (19-25 years old). This reduction was also seen in single trials, as were computed for one of the visual tasks. Moreover, in this data set, the single-trial Ne was also delayed for the elderly compared with the young. These data suggest an alteration of error detection in the elderly, which is only marginally reflected in performance.
Adult↗
ERP components on reaction errors and their functional significance: a tutorial.
Some years ago we described a negative (Ne) and a later positive (Pe) deflection in the event-related brain potentials (ERPs) of incorrect choice reactions [Falkenstein, M., Hohnsbein, J., Hoormann, J., Blanke, L., 1990. In: Brunia, C.H.M., Gaillard, A.W.K., Kok, A. (Eds.), Psychophysiological Brain Research. Tilburg Univesity Press, Tilburg, pp. 192-195. Falkenstein, M., Hohnsbein, J., Hoormann, J., 1991. Electroencephalography and Clinical Neurophysiology, 78, 447-455]. Originally we assumed the Ne to represent a correlate of error detection in the sense of a mismatch signal when representations of the actual response and the required response are compared. This hypothesis was supported by the results of a variety of experiments from our own laboratory and that of Coles [Gehring, W. J., Goss, B., Coles, M.G.H., Meyer, D.E., Donchin, E., 1993. Psychological Science 4, 385-390. Bernstein, P.S., Scheffers, M.K., Coles, M.G.H., 1995. Journal of Experimental Psychology: Human Perception and Performance 21, 1312-1322. Scheffers, M.K., Coles, M. G.H., Bernstein, P., Gehring, W.J., Donchin, E., 1996. Psychophysiology 33, 42-54]. However, new data from our laboratory and that of Vidal et al. [Vidal, F., Hasbroucq, T., Bonnet, M., 1999. Biological Psychology, 2000] revealed a small negativity similar to the Ne also after correct responses. Since the above mentioned comparison process is also required after correct responses it is conceivable that the Ne reflects this comparison process itself rather than its outcome. As to the Pe, our results suggest that this is a further error-specific component, which is independent of the Ne, and hence associated with a later aspect of error processing or post-error processing. Our new results with different age groups argue against the hypotheses that the Pe reflects conscious error processing or the post-error adjustment of response strategies. Further research is necessary to specify the functional significance of the Pe.
Adult↗
Different error types and error processing in spatial stimulus-response-compatibility tasks: behavioural and electrophysiological data.
We tested the hypothesis that in spatial stimulus-response-compatibility (SRC) tasks two different error types occur: A noise-induced 'general error' independent of SRC and reaction time and a 'position driven error' in incompatible trials with short RT being driven by the irrelevant stimulus position. A second issue was whether error detection is different for these two types of errors, which should be reflected by differences in the error negativity (Ne), since the Ne is seen as a neural correlate of error detection. To study these issues, we used a Simon- and a spatial Stroop-task. In incompatible (vs. compatible) trials we found more errors and a below chance accuracy in fast responses. Neither the amplitude nor the latency of the Ne were significantly affected by the experimental factors. This pattern of behavioural results supports the above hypothesis of two error types in such tasks. The Ne results indicate that error detection is similar for both types of errors.
Adult↗
Early attention effects in human auditory-evoked potentials.
A fundamental question in attention theory concerns the earliest processing stages that can be modulated by selective attention. A series of experiments is reported in which very early attention effects are found under specific conditions in the frequency-following potential (FFP), a brain stem response to low-frequency tone stimuli. In two experiments, stimuli of two different modalities were applied, and attention directed to one of the modalities. In two further experiments, only auditory stimuli were presented. In the first of these last two experiments, a dichotic paradigm with sustained attention to one ear was used, in the second a monotic paired-stimuli paradigm was used, in which the first stimulus served as reference for the second one. Only in the last experiment significant attention effects were found in the latency, but not in the amplitude of the FFP. The results show that a very early attention effect on the latency of the FFP can be demonstrated, but only under highly specific conditions. The size and preconditions of the attention effect suggest that it reflects subtle intramodal tuning mechanisms in the cochlea or in the lower brain stem.
Acoustic Stimulation↗
ERP components in Go/Nogo tasks and their relation to inhibition.
In visual Go/Nogo tasks the ERP usually shows a frontal negativity after Nogo stimuli ("Nogo-N2"), which possibly reflects an inhibition process. However, the Nogo-N2 appears to be very small after auditory stimuli, which is evidence against the inhibition hypothesis. In the present study we tested this hypothesis by evaluating performance differences between subjects. Assuming that for Ss with a high false alarm rate the inhibition process is weakened and/or delayed, they should reveal a smaller and/or later Nogo-N2 than Ss with a low false alarm rate. This prediction was confirmed, which supports the inhibition hypothesis. However, the Nogo-N2 was again much smaller and had a different topography after auditory than after visual stimuli despite similar performance in both modalities. This modality asymmetry was explained by assuming that the inhibitory mechanism reflected in the Nogo-N2 is located at a pre-motor rather than at the motor level. In the second part of the study we compared the Nogo-N2 with a similar phenomenon, the error negativity (Ne), which occurs in trials with commission errors (false alarms). Earlier work suggests that the Ne is a correlate of error detection or inhibition. This raises the possibility that the Ne is a delayed Nogo-N2, i.e., the Ne may reflect a late and hence unsuccessful attempt to inhibit the response after a nontarget. However, the Ne amplitude showed no difference between performance groups and stimulus modalities, as found for the Nogo-N2. Moreover, Ne and Nogo-N2 had different scalp topographies. This suggests that different mechanisms and generators underlie the Ne and the Nogo-N2.
Adolescent↗
Performance differences in reaction tasks are reflected in event-related brain potentials (ERPs).
Event-related potentials (ERPs), which can be extracted from the electroencephalogram (EEG), are assumed to reflect distinct cognitive processes in real time. Hence ERP analysis could be used in cognitive ergonomics as a tool to specify, for example, bottlenecks or sources of individual performance differences. Such specific results may be helpful to change the tasks or train the subjects specifically. In the present exploratory study, the authors investigated whether subjects with large spontaneous differences in performance accuracy, as defined by their error rates in a speeded binary choice reaction task, also differ in the structure of their ERPs. The ten subjects were divided post hoc into two groups with relatively low (about 6%) and high (about 20%) error rates. While the reaction times were not significantly different for both groups, the ERPs revealed clear group differences. First, large differences were seen in the late part of the contingent negative variation (late CNV), which is assumed to reflect preparatory processes. Subjects with few errors ('GOOD') had a large late CNV, while subjects with many errors ('POOR') showed virtually no late CNV. Second, the late P300-subcomponent (which is related to response identification) was smaller and delayed for POOR compared to GOOD subjects. Finally, the ERP shows signs of poor movement control in POOR subjects. The high error rate of POOR subjects can hence be explained by: (1) their insufficient preparation for the next trial (small late CNV), which impaired response identification (small and delayed late P300 subcomponent); and (2) their poor movement control. These interpretations have to be regarded as preliminary and should be validated with larger groups of subjects. In conclusion, the main reasons for the profound performance differences between the groups, namely differential preparation and movement control, could be elucidated by ERP analysis. A potential ergonomics application of these results is that they suggest specific strategies (for example, a preparation and motor control training) to improve the performance of POOR subjects in comparable work conditions.
Adult↗
A method to improve the latency estimation of the frequency-following potential (FFP).
If the latency of a noisy frequency-following potential (FFP) is estimated by determining the shift of the (periodical) cross-correlation function (CCF) between the stimulus and the FFP, the result may be unambiguous only within +/-1 or +/-2 periods of the CCF, because the absolute maximum and adjacent local maxima may not be significantly different. Here we present a method to amplify this difference by applying amplitude modulated stimuli. Using this method we first illustrate the effect of the method by a simulation and then demonstrate its usefulness by measuring real FFPs and estimating their latencies.
Artifacts↗
[Event-related potential components related to errors].
Event-related potentials (ERPs) of error trials in choice tasks and Go/Nogo tasks are found to be considerably different from the ERPs of the correct trials: In error trial ERPs there is an additional negative (Ne) and an additional positive component (Pe) compared to correct trials. Amplitude and latency variation of both components in different experiments supports the hypothesis that these components reflect different aspects of error processing. The Ne is interpreted as a real-time correlate of error detection, as defined by a mismatch between cognitive representations of the erroneous response and the correct response. The variation of Pe with experimental variables is different from that of the Ne and it also from that of positive components in correct trials, and may therefore reflect an additional aspect of error processing, such as change of response strategies.
Adult↗
Late ERP components in visual and auditory Go/Nogo tasks.
In an audio-visual Go/Nogo paradigm we studied whether the Go/Nogo difference, usually found in the time range of the visual N2, is also present after auditory stimuli, which bears on the common response inhibition hypothesis of this N2 effect. Moreover the possible presence and variation of P300 subcomponents were studied with the goal of clarifying the reasons for the commonly observed P300 topography changes between Go and Nogo trials. To disentangle possible P300 subcomponents we applied a crossmodal divided attention (DA) condition, in which the subcomponents are known to be separated after auditory stimuli in choice tasks. An N2 effect was found after visual but not after auditory stimuli, which is evidence against the response-inhibition hypothesis. After visual stimuli a positive complex (P400) was seen, whereas after auditory stimuli two dissociated components (P400 and P507) were found instead. The P507 had a parietal maximum for both Go and Nogo trials. It was larger and it peaked later in Go than in Nogo trials. The P400 showed topographic differences between Go and Nogo trials, which could be explained by the overlap of the two subcomponents. We assume that (i) both subcomponents have a stable topography across response type, and (ii) the first subcomponent is invariant with response type, whereas the second (which overlaps the first one) is larger and peaks later on Go than on Nogo trials.
Acoustic Stimulation↗
Effects of attention and time-pressure on P300 subcomponents and implications for mental workload research.
Our approach to objective measures of mental workload is establishing relationships between components of the event-related brain potential (ERP) and information processing stages. These relationships can be used to infer the influence of specific workload conditions on specific processing stages. We recently showed that the ERP component P300 in choice tasks is composed of two subcomponents, P-SR and P-CR, which are time-related to stimulus-evaluation and response-selection. With these relations we could specify which processing stages were affected when certain workload conditions are varied. When attention was divided between the visual and auditory modalities compared to (unimodal) focused attention, the choice reaction time (RT) was prolonged, primarily in the auditory modality. This delay was mainly reflected in the P-CR latency, which shows that the division of attention mainly impairs the response-selection process in the auditory modality due to a bias of attention towards the visual modality. When the time-pressure was increased, the latency of the P-CR (and not of the P-SR) was shortened, but less than the choice RT. This suggests a (limited) acceleration of response-selection but not of stimulus evaluation. Since the response-selection process was accelerated less than the overt choice RT, an increase of the error rate was consequently observed. In summary we showed that increases of mental workload can induce accelerations or decelerations of specific processing stages which can be monitored by observing latency changes of the affiliated ERP components.
Adult↗
Analysis of mental workload with ERP indicators of processing stages.
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Brain↗
Event-related potential correlates of errors in reaction tasks.
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Bias↗
Effect of selective attention on the latency of human frequency-following potentials.
While effects of attention on late and middle latency components of the evoked potential have been demonstrated, similar effects on brain stem evoked potentials--in particular on the human frequency-following potential (FFP)--are controversial. The FFP is a response to tone bursts in the frequency range of human language (optimum approximately 350 Hz). It has a latency of approximately 6.3 ms and is probably generated at a site peripheral to the inferior colliculus. We present data showing that the latency of the FFP can be shortened significantly (45 microseconds) if the subject is required to attend to the evoking auditory tone burst, while the amplitude of the FFP remains unaffected. This indicates an attention-controlled influence on signal processing in the earliest parts of the auditory pathway.
Acoustic Stimulation↗