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Hilde Haider

Publications and source records attributed to Hilde Haider.

14 recordsLinked to original sources
PubMed2006

The role of task rules and stimulus-response mappings in the task switching paradigm.

Switch costs occur whenever participants are asked to switch between two or more task sets. In a typical task switching experiment, participants have to switch between two task sets composed of up to four different stimuli per task set. These 2 (task sets) x 4 (stimuli) contain only 8 different stimulus-response (S-R) mappings, and the question is why participants base their task performance on task sets instead of S-R mappings. The current experiments compared task performance based on task rules with performance based on single stimulus-response mappings. Participants were led to learn eight different S-R mappings with or without fore-knowledge about two underlying task sets. Without task set information no difference between shifts and repetitions occurred, whereas introducing task sets at the beginning led to significant switch costs. Most importantly, introducing task sets in the middle of the experiment also resulted in significant switch costs. Furthermore, introducing task rules at the beginning of the experiment lead to slower RTs when simple stimuli (Experiment 1) had to be processed. This detrimental effect disappeared with more complex stimuli (Experiment 2). Results will be discussed with respect to cognitive control.

Adolescent↗
PubMed2006

Implicit task sets in task switching?

In 2 experiments, the authors compare stimulus-based versus task-rule-based task performance. Participants practiced 8 stimulus-response mappings either with or without knowledge about 2 underlying task sets. After practice, 2 transfer blocks with 8 new stimuli were presented. Results show that rule knowledge leads to significant switch and transfer costs, whereas without rule knowledge neither switch nor transfer costs occur. However, significant Task Type x Response Type interactions occurred in both conditions. In a second experiment including only the no rule condition, half of the stimulus-response mappings in the transfer blocks were incongruent to the underlying task rule. Slower response times for these incongruent stimuli as compared with congruent stimuli and the absence of switch costs suggest that participants acquired (presumably implicit) knowledge about 4 different stimulus-response categories.

Adolescent↗
PubMed2006

Precursors of insight in event-related brain potentials.

Event-related potentials (ERPs) were investigated to find precursors of insightful behavior. Participants had to process successive pairs in strings of digits to obtain a final response in each trial. Within the sequence of five responses required in each trial, the last two responses mirrored the two preceding ones. This hidden regularity, allowing for shortcutting each trial from five to two responses, was discovered by 6 out of 26 participants. Both groups, solvers and nonsolvers, implicitly learned the regularity, reflected by faster responses to the repeated, predictable responses, but this differential effect was larger in solvers, whereas nonsolvers became unspecifically faster with all responses. Several ERP components were larger in solvers than in nonsolvers from the outset: slow positive wave, frontocentral P3a, anterior N1 to those digits that triggered the critical repeating responses, and P3b to the digit that evoked the immediately repeating response. Being already present in the first block, these effects were early precursors of insightful behavior. This early occurrence suggests that participants who will gain insight may be distinguished beforehand by their individual characteristics.

Adult↗
PubMed2006

Preparatory adjustment of cognitive control in the task switching paradigm.

In this article, the authors investigate the assumption that preparation while switching between cognitive tasks is dynamically adjusted to the current task demands. Performance in high-shift blocks (75% shifts) was compared with performance in high-repetition blocks (75% repetitions). This probability information was given either at the beginning of a block (global condition) or by specific probability cues before every trial (local condition). The authors report strong preparation effects (activation of the probable task and inhibition of the improbable task) in high-shift blocks, especially when specific probability cues were provided. In high-repetition blocks, however, the preparation effects were less pronounced. The results support the assumption that preparation is dynamically adjusted to the expected task requirements.

Adolescent↗
PubMed2005

The generation of conscious awareness in an incidental learning situation.

The purpose of the present experiments was to investigate the generation of conscious awareness (i.e., of verbal report) in an incidental learning situation. While the single-system account assumes that all markers of learning, verbal or nonverbal, index the same underlying knowledge representation, multiple-systems accounts grant verbal report a special status as a marker of learning because they assume that the nonverbal and verbal effects of learning rely on different memory representations. We tested these two accounts in two experiments in which we held the amount of learning in the nonverbal memory system constant while manipulating independent variables aimed at affecting learning in the declarative system. The results of both experiments revealed significant differences in verbal report between experimental conditions, but no significant differences in response times. Overall, these results provide clear evidence in favor of the multiple-systems account.

Adolescent↗
PubMed2005

Are strategy shifts caused by data-driven processes or by voluntary processes?

The present research investigates the role of voluntary, conscious processing in strategy change. In 2 experiments, we address whether the switch to a new strategy is the result of data-driven, automatic processes or of voluntary processes. Experiment 1 demonstrates that participants performing an alphabet verification task are able to (a) transfer a newly adopted strategy to dissimilar information never encountered before, (b) verbally describe the task regularity that allows for the generation and application of the new strategy immediately after the strategy was adopted. Using the same experimental task, Experiment 2 shows that participants, and (c) decide against adopting a new strategy when the available evidence suggests that the new strategy cannot be used for the entire range of problems encountered. Overall, the obtained results support the view that strategy change is mediated by voluntary controlled processing. They do not support the view that strategy change is an inevitable, automatic consequence of task practice. The present research thus highlights a potential function of conscious human processing.

Adult↗
PubMed2005

Unconscious detection of implicit expectancies.

The detection of unexpected events is a fundamental process of learning. Theories of cognitive control and previous imaging results indicate a prominent role of the prefrontal cortex in the evaluation of the congruency between expected and actual outcome. In most cases, this attributed function is based on results where the person is consciously aware of the discrepancy. In this functional magnetic imaging (fMRI) study, we examined violations of predicted outcomes that did not enter conscious awareness. Two groups were trained with nearly identical material and the effects of new stimuli were assessed after learning. For the first group, the material was arranged with a hidden regularity. In this incidental learning situation, volunteers acquired implicit knowledge about structural response regularities as was demonstrated by an increase in reaction time when introducing new stimuli that violated the learned relations. To differentiate the detection process of stimuli that deviate from learned expectations from more unspecific effects generated by novel, unfamiliar stimuli, the second group was trained with rearranged material without a hidden regularity. No behavioral effects were found for the introduction of new stimuli in the group without implicit learning. Comparing the two groups, specific fMRI effects concerning the violation of implicitly learned expectations were found in the ventral prefrontal cortex and in the medialtemporal lobe. In accord with theories of learning, the results show a direct influence of the detection of prediction errors on the neuronal activity in learning related structures even in the absence of conscious knowledge about the predictions or their violations.

Adult↗
PubMed2004

Sleep inspires insight.

Insight denotes a mental restructuring that leads to a sudden gain of explicit knowledge allowing qualitatively changed behaviour. Anecdotal reports on scientific discovery suggest that pivotal insights can be gained through sleep. Sleep consolidates recent memories and, concomitantly, could allow insight by changing their representational structure. Here we show a facilitating role of sleep in a process of insight. Subjects performed a cognitive task requiring the learning of stimulus-response sequences, in which they improved gradually by increasing response speed across task blocks. However, they could also improve abruptly after gaining insight into a hidden abstract rule underlying all sequences. Initial training establishing a task representation was followed by 8 h of nocturnal sleep, nocturnal wakefulness, or daytime wakefulness. At subsequent retesting, more than twice as many subjects gained insight into the hidden rule after sleep as after wakefulness, regardless of time of day. Sleep did not enhance insight in the absence of initial training. A characteristic antecedent of sleep-related insight was revealed in a slowing of reaction times across sleep. We conclude that sleep, by restructuring new memory representations, facilitates extraction of explicit knowledge and insightful behaviour.

Adolescent↗
PubMed2003

Backward inhibition as a means of sequential task-set control: evidence for reduction of task competition.

Endogenously initiated transitions between tasks are associated with inhibition of the attentional set for the task preceding the transition, as demonstrated by slowed reactions to a task most recently switched away from (U. Mayr & S. W. Keele, 2000). Using an altered methodological approach, the authors found that this backward inhibition counteracts perseverative tendencies when switching to a new task in that it selectively reduces interference exerted by the preceding task set. The reduction of interference was dependent on endogenous preparation for the new task and did not occur for unpredictable task switches or for task switches that were precued without information about the identity of the new task.

Adolescent↗
PubMed2002

The role of medial temporal lobe structures in implicit learning: an event-related FMRI study.

The medial temporal lobe (MTL) has been associated with declarative learning of flexible relational rules and the basal ganglia with implicit learning of stimulus-response mappings. It remains an open question of whether MTL or basal ganglia are involved when learning flexible relational contingencies without awareness. We studied learning of an explicit stimulus-response association with fMRI. Embedded in this explicit task was a hidden structure that was learnt implicitly. Implicit learning of the sequential regularities of the "hidden rule" activated the ventral perirhinal cortex, within the MTL, whereas learning the fixed stimulus-response associations activated the basal ganglia, indicating that the function of the MTL and the basal ganglia depends on the learned material and not necessarily on the participants' awareness.

Adult↗
PubMed2002

Why aggregated learning follows the power law of practice when individual learning does not: comment on Rickard (1997, 1999), Delaney et al. (1998), and Palmeri (1999).

The power law of practice is often considered a benchmark test for theories of cognitive skill acquisition. Recently, P. F. Delaney, L. M. Reder, J. J. Staszewski, and F. E. Ritter (1998), T. J. Palmeri (1999), and T. C. Rickard (1997, 1999) have challenged its validity by showing that empirical data can systematically deviate from power-function fits. The main purpose of the present article is to extend their explanations in two ways. First, the authors empirically show that abrupt changes in performance are not necessarily based on a shift from algorithm to memory-based processing, but rather and more generally, that they occur whenever a more efficient task strategy is generated. Second, the authors show mathematically and per simulation that power functions can perfectly fit aggregated learning curves even when all underlying individual curves are discontinuous. Therefore, the authors question conclusions drawn from fits to aggregated data.

Humans↗
PubMed2002

Preparatory processes in the task-switching paradigm: evidence from the use of probability cues.

The purpose of the investigations was to dissociate processes of task preparation from task execution in the task-switching paradigm. The basic assumption was that task repetitions have 2 advantages over task shifts: an activation advantage as a result of the execution of the same task type in the pretrial, and an expectation advantage, because participants, in general, implicitly expect a repetition. In Experiments 1-3, the authors explicitly manipulated expectancies by presenting cues that announced a shift and/or a repetition with probabilities of 1.00, .75, .50, or .25. Increasing latencies with decreasing probability for shifts and repetitions show that the expectation advantage can be equalized by preparation. However, the activation advantage represented by constant shift costs between tasks of the same probability is not penetrable by preparation. In Experiments 4 and 5, the authors found evidence that preparation involves activation of the expected task and inhibition of distracting tasks.

Adaptation, Psychological↗
PubMedDate not supplied

The relevance of the nature of learned associations for the differentiation of human memory systems.

In a previous functional magnetic resonance imaging (fMRI) study we demonstrated an involvement of the medial temporal lobe (MTL) during an implicit learning task. We concluded that the MTL was engaged because of the complex contingencies that were implicitly learned. In addition, the basal ganglia demonstrated effects of a paralleled proceduralization of fixed stimulus-response associations. In the present study we directly tested the hypothesis that the MTL activation depends upon implementing the complex regularity in task material, whereas activation of basal ganglia does not. Therefore, we rearranged task material such that it did not contain any complex regularity. The statistical comparison of behavioral and fMRI data between the materials allowed for isolating effects that were directly related to the implicit learning process regarding the complex regularity. The results showed a reliable difference of fMRI signal limited to the MTL, indicating a specific functional role of the MTL in implicit learning of complex contingencies. Furthermore, no difference of BOLD (Blood-Oxygenation Level Dependent) signal in the basal ganglia and cerebellum were detected, supporting the assumption of a functional involvement of the structures in proceduralization of simple stimulus-response associations but not in implicitly learning complex relations. We therefore conclude that the nature of the learned associations is relevant for determining the neuronal focus of learning, rather than the accompanying awareness.

Adult↗