Publications (31)93.01 Total impact
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Article: Effects of response force parameters on medial-frontal negativity.
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ABSTRACT: The response-related medial-frontal activity (MFN) is often supposed to reflect action-monitoring and error-processing activity. The present force-production task was designed to investigate the effects of two response parameters (i.e., peak response force and time-to-peak, TTP) on the MFN separately. In a 2 × 2 design (high vs. low target force and short vs. long TTP), 22 participants had to produce isometric force pulses to match one of four conditions (e.g., a high target force with a long TTP). Significant main effects of both target force and target TTP were revealed. As previously shown, the MFN amplitude was higher in the high target-force condition than in the low target-force condition. Contrary to the initial expectations, a long TTP had the effect of reducing the MFN amplitude. There was no error-specific effect on the MFN. The force-unit monitoring model (FUMM) is suggested to account for the force- and TTP- specific variations of MFN amplitude, latency and slope.PLoS ONE 01/2013; 8(1):e54681. · 4.09 Impact Factor -
Article: Self-Awareness and Health-Related Quality of Life After Traumatic Brain Injury.
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ABSTRACT: OBJECTIVE:: To investigate the relations among self-awareness (SA), impaired SA, and health-related quality of life (HRQOL) after traumatic brain injury (TBI). PARTICIPANTS:: One hundred forty-one adults hospitalized with TBI and their significant others from a cross-sectional multicenter study. Using Glasgow Coma Scale classification, 32 participants had severe injuries, 29 moderate, 44 mild, and 25 complicated mild TBI. MEASURES:: Patient Competency Rating Scale for Neurorehabilitation; Short Form-36 Health Survey; Cognitive Quality of Life; Quality Of Life after Brain Injury; Hospital Anxiety and Depression Scale; Profile of Mood States; Glasgow Outcome Scale Extended. METHOD:: Patient Competency Rating Scale for Neurorehabilitation ratings made by participants and their significant others were used to assess SA and discrepancies between the 2 ratings were used to define impaired SA. RESULTS:: Significant associations were identified between SA and HRQOL, anxiety, depression, and severity of injury. Participants with and without impaired SA differed in cognitive HRQOL and leisure activities. Using multiple regression, no direct predictors of SA were identified, although interaction effects were observed. CONCLUSION:: After TBI, lower SA is associated with higher estimates of HRQOL, particularly in the cognitive domain. Although the associations are modest, the assessment of SA should play a role in the interpretation of reported HRQOL after TBI.The Journal of head trauma rehabilitation 08/2012; · 2.39 Impact Factor -
Article: QOLIBRI Overall Scale: a brief index of health-related quality of life after traumatic brain injury.
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ABSTRACT: The Quality of Life after Brain Injury (QOLIBRI) scale is a recently developed instrument that provides a profile of health-related quality of life (HRQoL) in domains typically affected by brain injury. However, for global assessment it is desirable to have a brief summary measure. This study examined a 6-item QOLIBRI Overall Scale (QOLIBRI-OS), and considered whether it could provide an index of HRQoL after traumatic brain injury (TBI). The properties of the QOLIBRI-OS were studied in a sample of 792 participants with TBI recruited from centres in nine countries covering six languages. An examination of construct validity was undertaken on a subsample of 153 participants recruited in Germany who had been assessed on two relevant brief quality of life measures, the Satisfaction With Life Scale and the Quality of Life Visual Analogue Scale. The reliability of the QOLIBRI-OS was good (Cronbach's α=0.86, test-retest reliability =0.81) and similar in participants with higher and lower cognitive performance. Factor analysis indicated that the scale is unidimensional. Rasch analysis also showed a satisfactory fit with this model. The QOLIBRI-OS correlates highly with the total score from the full QOLIBRI scale (r=0.87). Moderate to strong relationships were found among the QOLIBRI-OS and the Extended Glasgow Outcome Scale, Short-Form-36, and Hospital Anxiety and Depression scale (r=0.54 to -0.76). The QOLIBRI-OS showed good construct validity in the TBI group. The QOLIBRI-OS assesses a similar construct to the QOLIBRI total score and can be used as a brief index of HRQoL for TBI.Journal of neurology, neurosurgery, and psychiatry 07/2012; 83(11):1041-7. · 4.87 Impact Factor -
Article: Monitoring force errors: medial-frontal negativity in a unimanual force-production task.
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ABSTRACT: The effects of force production on medial-frontal negativity (MFN), reflecting the activity of an internal action-monitoring system, were investigated in a force-production task. A precue indicated a low or high force before a stimulus signaled the execution of the same or opposite force. An incorrectly exerted force was assumed to involve an error of force selection if the opposite force was required (invalid precue), and an error of force execution if the same force was required (valid precue). The task was repeated to examine any improvements in monitoring sensitivity. No force-related effects were observed on MFN amplitude. Although performance improved, there was no evidence of a force-error sensitive monitoring system. As the MFN and motor activity were affected by the precue invalidity regardless of the response outcome, the MFN might reflect the activity of a general action-evaluation system that is indirectly related to motor activation.Psychophysiology 09/2011; 49(1):56-72. · 3.29 Impact Factor -
Article: Prime retrieval of motor responses in negative priming: evidence from lateralized readiness potentials.
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ABSTRACT: In two experiments using a sequential prime-probe design we analyzed whether distractors repeated as targets retrieve the former prime response, although the prime response had to be withheld until after probe responding. Following Gibbons and Stahl (2008), we applied the lateralized readiness potential (LRP) as a measure for the retrieval of compatible or incompatible motor activation from the prime. When targets retrieved episodes containing the same response hand, the LRP onset occurred earlier, whereas when targets retrieved episodes containing the other response hand, the LRP onset was delayed. This data pattern supports prime-response retrieval theories of negative priming (Mayr and Buchner, 2006; Rothermund, De Houwer, and Wentura, 2005). In addition, the results show that executing a prime response is not a precondition for stimulus-response bindings.Brain research 08/2011; 1407:69-78. · 2.46 Impact Factor -
Article: An ERP study of target competition: individual differences in functional impulsive behavior.
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ABSTRACT: The present event-related potential (ERP) study aimed at investigating the specific behavioral and electrophysiological correlates of target competition, and their relationships to individual differences in functional impulsivity. Twenty-two participants performed a modified XO task with two conditions. Target competition displays included one up to three identical targets and no distractor, whereas distractor competition displays always included one target among one up to three distractors. On every trial, (one of) the target(s) had to be localized. Behavioral data revealed response time (RT) increases with increasing number of stimuli in both conditions. P2, N2, and P3 components were specifically responsive to target competition. High functional impulsives showed larger P2 for multiple- compared to single-target displays, but no effects on N2, P3, and RT. By contrast, in low functional impulsives target competition led to N2 increase, P3 decrease, and RT increase, while P2 effects were absent. Findings suggest that functional impulsives are better able to adapt to task requirements; in the present task they avoided conflict from multiple-target displays through better target discrimination at early stages of processing.International journal of psychophysiology: official journal of the International Organization of Psychophysiology 07/2011; 81(1):12-21. · 3.05 Impact Factor -
Article: Percept-based and object-based error processing: an experimental dissociation of error-related negativity and error positivity.
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ABSTRACT: Investigated the effect of presentation duration of masked visual stimuli and presentation mode (randomized, blocked) on error-related negativity (ERN) and error positivity (Pe). In two experiments, participants responded with the left and right hand to leftward and rightward arrows presented for different durations (0-117 ms). Different stimulus durations were fully randomized in Experiment 1 but run in separate blocks in Experiment 2. In both experiments, percent correct and Pe amplitude increased with increasing stimulus duration. By contrast, ERN was only found for (blocked) longer stimulus durations of Experiment 2, and absent with the randomized stimulus durations of Experiment 1. Presence of a Pe in the absence of ERN in Experiment 1 suggests that conscious error processing can occur without prior unconscious error detection. To explain the pattern of ERN/Pe effects, two separate processes of error detection are suggested, operating independently at the levels of object-based (Pe) and purely perceptual stimulus representations (ERN), respectively. A novel model of error processing is developed, elaborating on the reinforcement-learning theory of ERN. It is suggested that giving a response retrieves appropriate stimulus representations whose activation typically precedes this response; in case of mismatch with actually present stimuli, ERN is elicited.Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 02/2011; 122(2):299-310. · 3.12 Impact Factor -
Article: Temporal dynamics of conflict monitoring and the effects of one or two conflict sources on error-(related) negativity.
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ABSTRACT: The present electrophysiological study investigated the temporal development of response conflict and the effects of diverging conflict sources on error(-related) negativity (Ne). Eighteen participants performed a combined stop-signal flanker task, which was comprised of two different conflict sources: a left-right and a go-stop response conflict. It is assumed that the Ne reflects the activity of a conflict monitoring system and thus increases according to (i) the number of conflict sources and (ii) the temporal development of the conflict activity. No increase of the Ne amplitude after double errors (comprising two conflict sources) as compared to hand- and stop-errors (comprising one conflict source) was found, whereas a higher Ne amplitude was observed after a delayed stop-signal onset. The results suggest that the Ne is not sensitive to an increase in the number of conflict sources, but to the temporal dynamics of a go-stop response conflict.Biological psychology 09/2010; 85(1):112-23. · 4.36 Impact Factor -
Article: Quality of Life after Brain Injury (QOLIBRI): scale development and metric properties.
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ABSTRACT: The consequences of traumatic brain injury (TBI) for health-related quality of life (HRQoL) are poorly investigated, and a TBI-specific instrument has not previously been available. The cross-cultural development of a new measure to assess HRQoL after TBI is described here. An international TBI Task Force derived a conceptual model from previous work, constructed an initial item bank of 148 items, and then reduced the item set through two successive multicenter validation studies. The first study, with eight language versions of the QOLIBRI, recruited 1528 participants with TBI, and the second with six language versions, recruited 921 participants. The data from 795 participants from the second study who had complete Glasgow Coma Scale (GCS) and Glasgow Outcome Scale (GOS) data were used to finalize the instrument. The final version of the QOLIBRI consists of 37 items in six scales (see Appendix ). Satisfaction is assessed in the areas of "Cognition," "Self," "Daily Life and Autonomy," and "Social Relationships," and feeling bothered by "Emotions," and "Physical Problems." The QOLIBRI scales meet standard psychometric criteria (internal consistency, alpha = 0.75-0.89, test-retest reliability, r(tt) = 0.78-0.85). Test-retest reliability (r(tt) = 0.68-0.87) as well as internal consistency (alpha = 0.81-0.91) were also good in a subgroup of participants with lower cognitive performance. Although there is one strong HRQoL factor, a six-scale structure explaining additional variance was validated by exploratory and confirmatory factor analyses, and with Rasch modeling. The QOLIBRI is a new cross-culturally developed instrument for assessing HRQoL after TBI that fulfills standard psychometric criteria. It is potentially useful for clinicians and researchers conducting clinical trials, for assessing the impact of rehabilitation or other interventions, and for carrying out epidemiological surveys.Journal of neurotrauma 07/2010; 27(7):1167-85. · 4.25 Impact Factor -
Article: An ERP study of the processing of response conflict in a dynamic localization task: the role of individual differences in task-appropriate behavior.
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ABSTRACT: The study aimed at finding specific conflict-sensitive ERP components in a novel dynamic localization task. It was investigated whether these ERP components are sensitive to individual differences in task-appropriate behavior. Forty-four participants performed a localization task employing three differentially conflict-inducing experimental conditions: a frequent standard condition (O=target, X=distractor), a rare conflict condition (S=target, O=distractor), and a rare control condition (S=target, X=distractor). Behavioral data revealed increases of RT and error percent in the conflict condition. Early frequency-sensitive components P3a and fronto-central N2, and late conflict-sensitive components left-central N2, P3b, and CRN were observed. Two groups of participants were selected, those responding fast and accurately, and those responding slowly and inaccurately. Interestingly, the left-central N2 correlate of conflict was observed in the first group, whereas the CRN correlate was observed in the latter group. Findings suggest that pre-response conflict monitoring is required to successfully complete the task, whereas post-response conflict monitoring did not seem to improve performance. The present study used a novel dynamic localization task to identify ERP components that were sensitive to response conflict, but differentially predictive of good vs. poor task performance.Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 04/2010; 121(8):1358-70. · 3.12 Impact Factor -
Article: Flanker negative priming from spatially unpredictable primes: an ERP study.
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ABSTRACT: In a typical flanker task, a to-be-selected central target is flanked by two to-be ignored, identical distractors. The flanker negative priming (NP) effect denotes increased reaction time and error percent when the distractor of a first display serves as the target in the next. Most theories of NP are consistent with the idea that during processing of the first display, the identity of the distractors is inhibited. If the target of the subsequent display has the same identity, NP occurs because of persisting or retrieved inhibition. However, in the standard flanker task stimuli appear at the same screen locations for all trials, allowing for anticipatory spatial selection. No strong additional inhibition of stimulus identities may then be required. Therefore, besides the standard flanker task we employed a modified task in which the location of the stimulus triplet slightly differed across trials, thus disabling spatial pre-selection. Event-related potentials (ERPs) were recorded to identify brain correlates of NP in the two tasks. Behavioral NP was present in the modified task but absent in the standard task. An ERP correlate specific to NP in the modified task concerned larger amplitude of a left-posterior processing negativity. Results support the idea that stronger inhibition of distractor identities contributes to NP in the flanker task when spatial pre-selection is disabled.International journal of psychophysiology: official journal of the International Organization of Psychophysiology 03/2010; 75(3):339-48. · 3.05 Impact Factor -
Article: Quality of Life after Brain Injury (QOLIBRI): scale validity and correlates of quality of life.
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ABSTRACT: The QOLIBRI (Quality of Life after Brain Injury) is a novel health-related quality-of-life (HRQoL) instrument specifically developed for traumatic brain injury (TBI). It provides a profile of HRQoL in six domains together with an overall score. Scale validity and factors associated with HRQoL were investigated in a multi-center international study. A total of 795 adults with brain injury were studied from 3 months to 15 years post-injury. The majority of participants (58%) had severe injuries as assessed by 24-h worst Glasgow Coma Scale (GCS) score. Systematic relationships were observed between the QOLIBRI and the Glasgow Outcome Scale-Extended (GOSE), Hospital Anxiety and Depression Scale (HADS), and SF-36. Within each scale patients with disability reported having low HRQoL in two to three times as many areas as those who had made a good recovery. The main correlates of the total QOLIBRI score were emotional state (HADS depression and anxiety), functional status (amount of help needed and outcome on the GOSE), and comorbid health conditions. Together these five variables accounted for 58% of the variance in total QOLIBRI scores. The QOLIBRI is the first tool developed to assess disease-specific HRQoL in brain injury, and it contains novel information not given by other currently available assessments.Journal of neurotrauma 03/2010; 27(7):1157-65. · 4.25 Impact Factor -
Article: Event-related brain potential correlates of identity negative priming from overlapping pictures.
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ABSTRACT: Event-related potentials (ERPs) were obtained from an identity priming task, where a green target had to be selected against a superimposed red distractor. Several priming conditions were realized in a mix of control (CO), negative priming (NP), and positive priming (PP) trials. PP and NP effects in reaction times (RTs) were significant. ERP results conceptually replicate earlier findings of left-posterior P300 reduction in PP and NP trials compared to CO. This ERP effect may reflect the detection of prime-probe similarity corresponding to the concept of a retrieval cue. A novel finding concerned amplitude increase of the frontal late positive complex (LPC) in the order NP, CO, and PP. NP therefore seemed to induce brain activity related to cognitive control and/or memory processes, with reduced LPC amplitude indicating effortful processing. Overall, retrieval-based explanations of identity NP are supported.Psychophysiology 03/2010; 47(5):921-30. · 3.29 Impact Factor -
Article: Cognitive load reduces visual identity negative priming by disabling the retrieval of task-inappropriate prime information: an ERP study.
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ABSTRACT: The present event-related potentials (ERP) study investigated the mechanisms by which cognitive load reduces the negative priming (NP) effect in a letter flanker task. On each trial, participants (N=20) first encoded a set of one to five digits, then responded to two successive flanker displays (prime, probe), and finally recalled a certain digit from the set. The flanker NP effect (i.e., increased probe RT when the prime distractor repeated as the probe target) was significant under low (1-2 items) but not high cognitive load (4-5 items). NP in the low-load condition was accompanied by left-anterior P2/N2 amplitude modulation which was also observed for prime-probe target repetitions and hence may reflect the processing of prime-probe similarity. Under high load, the P2/N2 effect was absent. It is suggested that cognitive load interferes with a retrieval-based mechanism in NP. Findings support episodic-retrieval explanations of visual identity-based NP.Brain research 03/2010; 1330:101-13. · 2.46 Impact Factor -
Article: Quality of life after traumatic brain injury: the clinical use of the QOLIBRI, a novel disease-specific instrument.
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ABSTRACT: To report the clinical use of the QOLIBRI, a disease-specific measure of health-related quality-of-life (HRQoL) after traumatic brain injury (TBI). The QOLIBRI, with 37 items in six scales (cognition, self, daily life and autonomy, social relationships, emotions and physical problems) was completed by 795 patients in six languages (Finnish, German, Italian, French, English and Dutch). QOLIBRI scores were examined by variables likely to be influenced by rehabilitation interventions and included socio-demographic, functional outcome, health status and mental health variables. The QOLIBRI was self-completed by 73% of participants and 27% completed it in interview. It was sensitive to areas of life amenable to intervention, such as accommodation, work participation, health status (including mental health) and functional outcome. The QOLIBRI provides information about patient's subjective perception of his/her HRQoL which supplements clinical measures and measures of functional outcome. It can be applied across different populations and cultures. It allows the identification of personal needs, the prioritization of therapeutic goals and the evaluation of individual progress. It may also be useful in clinical trials and in longitudinal studies of TBI recovery.Brain Injury 01/2010; 24(11):1272-91. · 1.36 Impact Factor -
Article: Modeling single-trial LRP waveforms using gamma functions.
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ABSTRACT: The lateralized readiness potential (LRP) is a component of average event-related potentials that has proven very useful in the study of hand-specific motor preparation. We developed a model of single-trial LRP waveforms that produces realistic average waveforms for both stimulus-locked and response-locked averaging. This model may be useful in computer simulation studies of LRP scoring methods, and it may open up the possibility of ultimately retrieving trial-by-trial information about LRP activity.Psychophysiology 09/2009; 47(1):43-56. · 3.29 Impact Factor -
Article: Functional brain-electrical correlates of negative priming in the flanker task: evidence for episodic retrieval.
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ABSTRACT: Negative priming (NP) refers to inefficient responding when previous distractors become targets. NP may reflect persisting inhibition of former distractors and/or retrieval of task-inappropriate information from the primes. In an event-related potential (ERP) study of the flanker task, NP was accompanied by reduced positivity in the P300 time range. The early portion of this effect was shared with a target-repetition condition and hence may indicate retrieval processes cued by repeated stimuli. A subsequent N400-like component was specific for NP and may reflect processing of the retrieved task-inappropriate information. In addition, NP effects on the lateralized readiness potential (LRP) matched predictions of the episodic-retrieval view. NP effects on P300, N400, and response-locked LRP were stronger in participants with above-median behavioral NP, confirming the significance of these ERP effects for NP. Overall, findings support episodic-retrieval explanations of NP.Psychophysiology 05/2009; 46(4):807-17. · 3.29 Impact Factor -
Article: Evaluative priming from subliminal emotional words: insights from event-related potentials and individual differences related to anxiety.
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ABSTRACT: The present ERP study investigated effects of subliminal emotional words on preference judgments about subsequent visual target stimuli (paintings, portraits). Each target was preceded by a masked 17-ms emotional adjective. Four classes of prime words were distinguished according to the combinations of positive/negative valence and high/low arousal. Targets were liked significantly more after positive-arousing primes (e.g., happy), relative to negative-arousing (brutal), positive-nonarousing (mild), and negative-nonarousing primes (lazy). In the target ERP, amplitude of right-hemisphere positive slow wave was increased after positive-arousing compared to negative-arousing primes. Evaluative priming effects on judgments and ERPs were more pronounced in high state-anxious participants. The results suggest that (1) there is indeed affective/semantic processing of unconscious words, (2) evaluative priming operates relatively late during target processing, (3) to be effective, prime words need to score high on the arousal dimension, and (4) individual differences in state anxiety modulate the susceptibility to subliminal evaluative priming.Consciousness and Cognition 04/2009; 18(2):383-400. · 2.31 Impact Factor -
Article: ERP predictors of individual performance on a prospective temporal reproduction task.
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ABSTRACT: The present study aimed at investigating whether different aspects of performance on a prospective reproduction task with a standard duration of 2 s had different antecedents in the event-related potentials (ERPs) accompanying standard presentations and reproduced intervals. On each trial, first the standard duration was presented as an empty auditory interval. After a short delay, participants reproduced this interval by means of two button presses defining onset and offset of the reproduced interval. About 25 participants were divided into groups of poor and good time estimators, once based on the coefficient of variation of their reproduced durations, and once based on the absolute error score. Interestingly, for both performance measures differences between participants were accompanied by ERP differences during standard presentations rather than reproduction itself. While larger P300 amplitudes evoked by standard interval offset predicted good reproduction performance in terms of a small coefficient of variation, small absolute error scores were accompanied by larger fronto-central negative slow wave during standard presentations. The results suggest an important role of attention to both the critical events that delimit the to-be-estimated temporal intervals, and to the passing of time between these events.Psychological Research 06/2008; 72(3):311-20. · 2.47 Impact Factor -
Article: Early activity in the lateralized readiness potential suggests prime-response retrieval as a source of negative priming.
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ABSTRACT: Negative priming (NP) refers to increased response time (RT) for a probe target that was a distractor in a preceding prime presentation (distractor-target shift, DT), compared to novel targets. The present study used the lateralized readiness potential (LRP) to investigate, in a four-choice identification task, a novel episodic-retrieval explanation of NP introduced by Rothermund, Wentura, and de Houwer (2005). This theory proposes that retrieval reactivates the prime response which interferes with selection of the correct probe response, thereby producing NP. 20 participants responded to pairs of red and blue digits, contingent on the identity of the digit presented in the target color. Behavioral NP involved RT increase by 16 ms. With shift trials (different hands used for prime and probe responses), in the DT condition LRP onset was delayed relative to control. By contrast, earlier LRP onset was observed for DT relative to control with no-shift trials (same hand used for prime and probe responses). Behavioral NP effects showed similar magnitude for shift and no-shift trials. Results support the Rothermund et al. (2005) theory of prime-response retrieval.Experimental Psychology 02/2008; 55(3):164-72. · 2.22 Impact Factor
Top co-authors
Top Journals
- Psychophysiology (4)
- Psychophysiology (2)
- Clinical Neurophysiology (2)
- Journal of neurotrauma (2)
- Brain research (2)
Institutions
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2010–2013
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Universität Köln
Köln, North Rhine-Westphalia, Germany
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2004–2012
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Georg-August-Universität Göttingen
- • Department of Medical Psychology and Medical Sociology
- • Georg-Elias-Müller Institute for Psychology
Göttingen, Lower Saxony, Germany
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2011
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Universität des Saarlandes
Homburg, Saarland, Germany
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2009
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Universitätsmedizin Göttingen
Göttingen, Lower Saxony, Germany
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