Refine
Document Type
- Doctoral thesis (2)
Institute
- Psychologie (2) (remove)
Language
- English (2) (remove)
Keywords
- Kognition (2)
- Allgemeine Psychologie (1)
- Cognitive control (1)
- Denkfehler (1)
- Dual-tasking (1)
- Early error sensations (1)
- Elektroencephalographie (1)
- Error awareness (1)
- Error detection (1)
- Error monitoring (1)
Performance monitoring is a key function of human cognition and critical for
achieving goal-directed behavior. In recent years, research has particularly focused
on how the brain detects and evaluates behavioral errors. Most studies investigated
two neural correlates of performance monitoring in the human scalp EEG. In
particular, the error-related negativity (Ne/ERN) is a negative fronto-central deflection
observed immediately after an erroneous response, representing an early and
unconscious stage of error processing. The Ne/ERN is followed by the later error
positivity (Pe), a broader positivity viewed as a correlate of conscious error
processing. Whereas a large amount of research has been conducted on these
neural correlates, fundamental questions on their relationship remain. Crucially, it is
still unclear whether both components represent functionally independent processes
of error monitoring or whether the two components are part of a single mechanism.
The first possibility implies that the earlier Ne/ERN provides the basis for the later
emergence of the Pe and error awareness in a cascade-like architecture of error
monitoring. The other possibility is that the Pe and error awareness can emerge
independently of the Ne/ERN, which implies that different error monitoring
mechanisms exist and may proceed independently. The thesis addresses the
important question whether Ne/ERN provides necessary information for error
awareness and Pe. To this aim, behavioral and psychophysiological studies were
conducted:
(1) In a first part, we investigated whether Ne/ERN and Pe are causally related
(study 1). We developed a novel experimental paradigm based on the classical letters flanker task. In this paradigm, participants have to classify targets but ignore
irrelevant distractors (flankers) that are always associated with an incorrect
response. Targets but not flankers are masked with varying target-masking intervals.
On some trials, no target at all is presented, thus preventing the representation of a
correct response. Importantly, the lack of a representation of the correct response
also prevents the emergence of Ne/ERN. However, because flankers are easily
visible and responses to these flankers are always incorrect, conscious detection of
these flanker errors is still possible. The presence of a Pe in the absence of Ne/ERN
for flanker errors provides evidence for independent error monitoring processes.
(2) In a second part, we investigated whether the Ne/ERN and Pe are
differentially sensitive to temporal aspects of conscious error detection. Whereas the
Pe is assumed to be the earliest correlate of the emergence of conscious error
perception, participants often report the feeling of having detected an error even
before the erroneous response was actually executed (“early error sensations”). The
first goal of this part was to investigate whether such anecdotal evidence can be
measured empirically. In study 2, a series of behavioral experiments using different
methodological procedures were conducted. Participants during choice tasks have to
report whether errors were accompanied or not by early error sensations (i.e. early
and late detected errors) or give confidence judgments about early error sensations.
Participants frequently reported early errors with high level of confidence.
Subsequently, we studied how error-related brain activity reflects the emergence of
early error sensations. In study 3, we measured EEG activity and compared early
and late detected errors. Results showed that while the Pe reliably reflects the early
error sensations (larger amplitude for early errors), the Ne/ERN does not (no
differences between early and late errors). Crucially, the Ne/ERN and the Pe
responded differently to temporal aspects of error awareness, meaning that Ne/ERN
and Pe could rely on different types of information for error detection. This again
speaks for the idea of independent systems of error monitoring.
Cognitive control processes enable humans to break out of reflexive stimulus-response chains and to align their behavior towards self-imposed goals. Despite decades of research on the nature of these processes, they remain a complex and only partly comprehensible fabric of interactions and interdependencies. Three electroencephalographic studies aimed to increase knowledge about cognitive control by utilizing error precursors – neural activity preceding the occurrence of performance errors. Study 1 used error precursors to separate two preparatory control processes of a task-switching paradigm and to investigate their relative contribution to the emergence of task confusions. The results highlight the importance of general preparation in the form of cue encoding but also demonstrate how switch-specific preparatory activity can affect the selection of the currently relevant task set. In Study 2, preparatory processes were examined in the more complex environment of a dual-tasking paradigm. Distinct error precursors for the respective subtasks and a neural correlate of task order switches that is independent of these provide evidence for a multi-level system of control processes with advance prioritization of subtasks in dual-tasking. Study 3 finally focused on reactive control – adjustments to neural activity and behavior following unfavorable outcomes such as performance errors. Here, error precursors serve as a prerequisite to answer the question of adaptivity of post-error adjustments in visual search. The results confirm that a post-error reduction of target localization activity serves to attenuate a potential error source in this paradigm. In summary, the three studies of this doctoral thesis contribute to understanding the complex system of control processes by providing evidence for accounts that suggest well-established knowledge about control processes to be reconsidered in light of more fine-grained differentiation of the underlying subcomponents.