1,721,599 research outputs found
The dissipating task-repetition benefit in cued task-switching : exploring the role of task-set decay vs.temporal distinctiveness in episodic task retrieval
No full textIn everyday life, we are constantly confronted with changing demands in our environment and constantly happen to perform a multitude of tasks. Current theories describe cognitive control (Logan, 1985; Wood & Grafman, 2003) as the functional underlying mechanism which enables flexible adaptations of behavior. The task-switching paradigm allows to study cognitive control processes when switching between two different tasks with unpredictable order. The basic idea assumes that contrary to well practiced tasks, switching between unpracticed, poorly structured, or unpredictable tasks is linked to mental effort, called “switch costs” (higher reaction times and error rates) (Monsell, 2003). The critical manipulation of the present work concerned the interval between a response and the subsequent cue (i.e., the response-cue interval, RCI). Previous studies have shown that performance in a task repetition is worse after a long RCI compared to a short RCI. This result is traditionally interpreted as follows. Benefits of repeating a task (compared to switching tasks) depend on the activation of task representations (task set) in short-term memory, since this activation passively decays with time unless the task set is maintained (Meiran, Chorev, & Sapir, 2000). Against the background of rather mixed empirical results for theories on performance in task switching (e.g., Altmann, 2005), the work at hand presents the following result. Effects of timing manipulations in task switching, especially in repeating a task, cannot be explained by assuming automatic and passive decay of task sets. The theoretical contribution of the work at hand lies in offering an alternative account for RCI effects on the task-repetition benefit. It is assumed that performance when switching between tasks, among other factors, is influenced by the temporal distinctiveness of episodes (tasks). More specific, the present work proposes that RCI effects in task switching depend on the process of episodic retrieval. This episodic retrieval is modulated by the temporal distinctiveness of episodes, which is defined as the ratio between the current RCI and the preceding RCI. Further, the data imply that episodic retrieval during the RCI is linked to stimulus-related components of the task set. In seven experiments subjects switched between a color- and shape task. The RCI was manipulated in different ways. In Experiments 1 und 2 different ranges of RCIs were used. Increasing RCI decreased the task-repetition benefit, but the slope of the RCI function depended on the range of RCIs rather than on the absolute duration of the RCI. In Experiment 3, the RCIs were blocked or random, and in Experiment 4, trial-wise predictability of RCIs was manipulated. RCI influenced the task-repetition benefit only when RCI changed from the previous to the current trial. Experiment 5 used two cues for each task and dissociated cue-repetition priming from task-repetition priming, suggesting that perceptual cue repetition priming appears to decay, whereas episodic task-set retrieval is influenced by temporal distinctiveness. Experiments 6 und 7 examined which part of the task set (Meiran, 2000) plays a role in episodic retrieval during the RCI. In Experiment 6, response valence (bivalent vs. univalent) was manipulated. The results showed that lengthening the RCI leads to a loss of repetition benefit, mainly when the RCI changed from the previous trial to the current trial, but this was comparable for bivalent (response keys relevant for both tasks) and univalent responses (each response assigned to a separate key). In Experiment 7, stimulus valence was manipulated. The results revealed stronger RCI effects with bivalent stimuli compared to univalent stimuli. Taken together, the data suggest that the influence of RCI in task switching is linked to retrieval of stimulus-related task components (Stimulus-Set) rather than to response-related components (Response-Set). The data of the present work can best be explained by the account of temporal distinctiveness in episodic task retrieval
Exploring the role of work-related language switching experience and different tasks for language switch costs : an empirical study in the laboratory and within international companies
No full textAs the world globalizes more and more, English has become very important in many areas of life. This is the reason why also many companies adopted English as their corporate language to make international work easier. Consequently, we often are unexpectedly forced to switch between our native language and English. Current theories agree that language switching is linked to mental effort and higher control activities (e.g. Hernandez, Dapretto, Mazziotta, & Bookheimer, 2001) due to parallel activation of the two languages of a bilingual (e.g., Green, 1998). This parallel activity between languages is assumed to be solved via inhibition of the non-target language (Green, 1998). This work at hand investigates two research fields concerning language switching that are rather unexplored until today. First, language-switching performance is compared between language production and language reception tasks by testing the same participants in both tasks. Secondly, the language-switching performance of participants with work-related language-switching experience is compared with participants that were not experienced in language switching. In seven experiments participants switched between German (first/mother language = L1) and English (second learned language = L2) in different production and reception tasks. In Experiment 1 bilinguals participated in a productive digit-naming task and a receptive digit-categorization task. Results showed switch costs in both tasks, indicating slower reaction times (RTs) in switch trials (alternating languages within two consecutive trials) compared to no-switch trials (same language within two consecutive trials). Yet, switch costs were larger in the production than in the reception task. Besides that, participants inhibited their L1 generally (i.e., slower responses in L1 than in L2) in the production task. To exclude the assumption that results were influenced by dissimilar tasks in Experiment 1, in Experiment 2 the production and reception tasks were made more comparable to each other (both tasks contained categorization). However, participants again showed larger switch costs in production than in reception. For the production task, no general inhibition of L1 was found. Experiment 3 served as a control experiment to show that the general inhibition of L1 in Experiment 1 was not caused by a different speech onset between L1 and L2 stimuli in Experiment 1 in contrast to Experiment 2. Rather, it is suggested that participants raise their activation threshold in L1 to prevent premature responses in easy production tasks. Experiment 4 contained a productive direct-naming task and a productive digit-categorization task. Results supported the idea of a general inhibition of L1 to prevent easy responses. Again, switch costs were found in both tasks. Experiment 5 investigated whether easy reception tasks also cause participants to inhibit their L1 generally. Participants were tested in a number-reception task as well as in a category-reception task. Switch costs were found in both tasks. However, a general inhibition of L1 was found in neither task. Experiment 6 and 7 concentrated on comparing the performance difference between participants that were experienced in language switching with those that had no experience. Contrary to expectation, results were similar between the two groups of participants. That is, employees with work-related language-switching experience still showed substantial switch costs. The theoretical contribution of this work at hand lies in showing that language-switch costs which occur in different experimental settings and for participants with different language-switching experience are a robust empirical marker. However, the size of switch costs seems to depend on the type of task as results of this work showed that switch costs were larger in production compared to reception tasks (concerning RTs and error rates). This is interpreted in terms of an influence of the different input and output modalities as well as a higher between-language interference when participants switch languages in production contrary to reception tasks. Furthermore, other empirical markers in language-switching studies depend on the specific task requirements. For instance, it is suggested that a general inhibition of the dominant language occurs only in easy tasks in which a response in either language is required (e.g. direct-naming production task)
Effects of acute alcohol intoxication on visual processing and oculomotor control
No full textAlthough alcohol consumption is known to degrade performance in a variety of tasks, the exact character of alcohol induced impairments is currently not well understood. The present work examines to what extent acute alcohol intoxication impairs visual processing and oculomotor control on different processing levels. Understanding the impact of alcohol on the visual system is critical because the most important way humans navigate in and communicate with the environment is through the acquisition and processing of visual information. Virtually all complex cognitive tasks rely on visual input, obtained via the planning and execution of rapid eye movements. Within the theoretical framework of “active vision” (Findlay & Gilchrist, 2003) the traditional dissociation of perception from motor control is loosened and eye movements are regarded as ‘part and parcel’ of an integrated process of information acquisition. In order to better understand the stages at which alcohol affects oculomotor control, five paradigms were used to map alcohol effects on different hierarchically organized levels of visuomotor control and additionally two complex visual cognitive tasks were examined. On the lowest level (automatic), reflexive processes were tested using the pro saccade task. The next level (automated) incorporates implicit learning and memory processes that can influence reflexive behavior, but are still unconscious. This level was examined using the double step paradigm. The highest processing level represents voluntary modification of behavior and was studied using two versions of the anti saccade paradigm and the memory guided saccade paradigm. The two complex visual cognitive tasks were task switching and reading. Task switching requires participants to switch between two or more distinct tasks, which usually results in switch costs or benefits. Such effects are explained with the interplay of inhibition and activation and to date no study has examined effects of alcohol on performance in task switching. The sentence reading experiment offered the possibility to study visuomotor control in combination with a precisely controlled cognitive processing load in an ecologically valid everyday task. For all paradigms, participant’s performance were measured in an “alcohol” and a “no alcohol” session. A total of 62 students participated and the mean breath alcohol concentration in the “alcohol session” was 70mg%. Results indicate specific effects of alcohol on different levels of visual processing and oculomotor control. Functioning on the automatic level was intact, except for a slowing in saccade latencies. Even though alcohol is known to reduce simple reaction times, the present work could show for the first time that in comparison with higher processing levels, such a “general slowing” is less pronounced on this lower processing level. Regarding the automated level deficits with in the ability to adaptively reprogram saccades on the basis of new visual information were found under alcohol. More time is necessary to achieve the same amount of reprogramming when eye movements need to be directed to new target locations. This finding is especially important, because adaptive reprogramming is a core ingredient of effective visuomotor behavior in everyday tasks such as reading or visual search. Impairments on the voluntary processing level became apparent in hypermetric (i.e., prolonged) saccade amplitudes under alcohol, whenever a reprogramming of the initial saccade target was necessary. This effect was found under conditions that required endogenous representation as well as in situations when a visual marker was present at the target location. In addition, a small effect of alcohol on visuospatial short term memory was found. Interestingly, no alcohol related effects were found regarding inhibitory functioning. In addition, performance measures in the complex visual cognitive tasks did not differ between alcohol conditions as a result of compensatory mechanisms. Apparently, longer processing time that is available under alcohol can be used in the task switching condition to activate a task set more completely. In a similar way, the trade-off between increased fixation duration and decreased number of fixations during reading suggests that the extra processing time under alcohol can be used for linguistic processing, which in itself does not seem to be impaired. This finding is supported by the fact no interaction between alcohol and word frequency was found. In conclusion, this thesis explored the effects of acute alcohol intoxication on visual processing and oculomotor control. The carefully selected paradigms have yielded interesting findings that begin to map alcohol related impairments on different levels of oculomotor control. In addition, findings and discussions afford multiple approaches for further research that should help to achieve a deeper understanding of the effects of alcohol and its underlying mechanisms
Bewusste und unbewusste Informationsverarbeitung im Arbeitsgedächtnis : die Rolle von zentraler Exekutive und phonologischer Schleife
No full textNeuronale Korrelate der Vorhersage hierarchischer Stimulussequenzen
No full textIn daily life, we are enclosed by constantly changing structures. We perceive and learn to appreciate these so called stimulus sequences in order to appropriately adapt our behavior. For example, a step onto a moving escalator is exactly planned to avoid stumbling. But in case of an escalator not moving, the planning of the step has to be altered and adapted to the new situation. Such an adaptation of well experienced behavior is necessary after breaches of expectancy. In this dissertation, functional magnetic resonance imaging (fMRI) studies observe neural correlates of reorientation within well-known stimulus sequences after breaches of expectancy of different strength, and, of temporally remote effects after such breaches of expectancy. Moreover, it is described which cortical areas allow to efficiently predict long and hierarchically structured stimulus sequences. Data show that especially the activation of the frontopolar cortex (Brodmann Area (BA 10)) correlates with the hierarchical order of to-be-predicted stimulus sequences. While the temporally remote effect after breaches of expectancy is reflected in an attenuation of the dorsal frontomedian activity (BA 9m), the immediate reorientation, i.e. search for appropriate prediction, is reflected in activation of a complex cortical network. Thereby the (median) parietal areas can be interpreted as a regulating interface between the top-down information of prefrontal areas and bottom-up information of temporal areas. Furthermore, the anterior ventrolateral prefrontal cortex is activated the more, the less reorientation was necessary
Exploring the role of work-related language switching experience and different tasks for language switch costs : an empirical study in the laboratory and within international companies
No full textAs the world globalizes more and more, English has become very important in many areas of life. This is the reason why also many companies adopted English as their corporate language to make international work easier. Consequently, we often are unexpectedly forced to switch between our native language and English. Current theories agree that language switching is linked to mental effort and higher control activities (e.g. Hernandez, Dapretto, Mazziotta, & Bookheimer, 2001) due to parallel activation of the two languages of a bilingual (e.g., Green, 1998). This parallel activity between languages is assumed to be solved via inhibition of the non-target language (Green, 1998). This work at hand investigates two research fields concerning language switching that are rather unexplored until today. First, language-switching performance is compared between language production and language reception tasks by testing the same participants in both tasks. Secondly, the language-switching performance of participants with work-related language-switching experience is compared with participants that were not experienced in language switching. In seven experiments participants switched between German (first/mother language = L1) and English (second learned language = L2) in different production and reception tasks. In Experiment 1 bilinguals participated in a productive digit-naming task and a receptive digit-categorization task. Results showed switch costs in both tasks, indicating slower reaction times (RTs) in switch trials (alternating languages within two consecutive trials) compared to no-switch trials (same language within two consecutive trials). Yet, switch costs were larger in the production than in the reception task. Besides that, participants inhibited their L1 generally (i.e., slower responses in L1 than in L2) in the production task. To exclude the assumption that results were influenced by dissimilar tasks in Experiment 1, in Experiment 2 the production and reception tasks were made more comparable to each other (both tasks contained categorization). However, participants again showed larger switch costs in production than in reception. For the production task, no general inhibition of L1 was found. Experiment 3 served as a control experiment to show that the general inhibition of L1 in Experiment 1 was not caused by a different speech onset between L1 and L2 stimuli in Experiment 1 in contrast to Experiment 2. Rather, it is suggested that participants raise their activation threshold in L1 to prevent premature responses in easy production tasks. Experiment 4 contained a productive direct-naming task and a productive digit-categorization task. Results supported the idea of a general inhibition of L1 to prevent easy responses. Again, switch costs were found in both tasks. Experiment 5 investigated whether easy reception tasks also cause participants to inhibit their L1 generally. Participants were tested in a number-reception task as well as in a category-reception task. Switch costs were found in both tasks. However, a general inhibition of L1 was found in neither task. Experiment 6 and 7 concentrated on comparing the performance difference between participants that were experienced in language switching with those that had no experience. Contrary to expectation, results were similar between the two groups of participants. That is, employees with work-related language-switching experience still showed substantial switch costs. The theoretical contribution of this work at hand lies in showing that language-switch costs which occur in different experimental settings and for participants with different language-switching experience are a robust empirical marker. However, the size of switch costs seems to depend on the type of task as results of this work showed that switch costs were larger in production compared to reception tasks (concerning RTs and error rates). This is interpreted in terms of an influence of the different input and output modalities as well as a higher between-language interference when participants switch languages in production contrary to reception tasks. Furthermore, other empirical markers in language-switching studies depend on the specific task requirements. For instance, it is suggested that a general inhibition of the dominant language occurs only in easy tasks in which a response in either language is required (e.g. direct-naming production task)
Effects of acute alcohol intoxication on visual processing and oculomotor control
No full textAlthough alcohol consumption is known to degrade performance in a variety of tasks, the exact character of alcohol induced impairments is currently not well understood. The present work examines to what extent acute alcohol intoxication impairs visual processing and oculomotor control on different processing levels. Understanding the impact of alcohol on the visual system is critical because the most important way humans navigate in and communicate with the environment is through the acquisition and processing of visual information. Virtually all complex cognitive tasks rely on visual input, obtained via the planning and execution of rapid eye movements. Within the theoretical framework of “active vision” (Findlay & Gilchrist, 2003) the traditional dissociation of perception from motor control is loosened and eye movements are regarded as ‘part and parcel’ of an integrated process of information acquisition. In order to better understand the stages at which alcohol affects oculomotor control, five paradigms were used to map alcohol effects on different hierarchically organized levels of visuomotor control and additionally two complex visual cognitive tasks were examined. On the lowest level (automatic), reflexive processes were tested using the pro saccade task. The next level (automated) incorporates implicit learning and memory processes that can influence reflexive behavior, but are still unconscious. This level was examined using the double step paradigm. The highest processing level represents voluntary modification of behavior and was studied using two versions of the anti saccade paradigm and the memory guided saccade paradigm. The two complex visual cognitive tasks were task switching and reading. Task switching requires participants to switch between two or more distinct tasks, which usually results in switch costs or benefits. Such effects are explained with the interplay of inhibition and activation and to date no study has examined effects of alcohol on performance in task switching. The sentence reading experiment offered the possibility to study visuomotor control in combination with a precisely controlled cognitive processing load in an ecologically valid everyday task. For all paradigms, participant’s performance were measured in an “alcohol” and a “no alcohol” session. A total of 62 students participated and the mean breath alcohol concentration in the “alcohol session” was 70mg%. Results indicate specific effects of alcohol on different levels of visual processing and oculomotor control. Functioning on the automatic level was intact, except for a slowing in saccade latencies. Even though alcohol is known to reduce simple reaction times, the present work could show for the first time that in comparison with higher processing levels, such a “general slowing” is less pronounced on this lower processing level. Regarding the automated level deficits with in the ability to adaptively reprogram saccades on the basis of new visual information were found under alcohol. More time is necessary to achieve the same amount of reprogramming when eye movements need to be directed to new target locations. This finding is especially important, because adaptive reprogramming is a core ingredient of effective visuomotor behavior in everyday tasks such as reading or visual search. Impairments on the voluntary processing level became apparent in hypermetric (i.e., prolonged) saccade amplitudes under alcohol, whenever a reprogramming of the initial saccade target was necessary. This effect was found under conditions that required endogenous representation as well as in situations when a visual marker was present at the target location. In addition, a small effect of alcohol on visuospatial short term memory was found. Interestingly, no alcohol related effects were found regarding inhibitory functioning. In addition, performance measures in the complex visual cognitive tasks did not differ between alcohol conditions as a result of compensatory mechanisms. Apparently, longer processing time that is available under alcohol can be used in the task switching condition to activate a task set more completely. In a similar way, the trade-off between increased fixation duration and decreased number of fixations during reading suggests that the extra processing time under alcohol can be used for linguistic processing, which in itself does not seem to be impaired. This finding is supported by the fact no interaction between alcohol and word frequency was found. In conclusion, this thesis explored the effects of acute alcohol intoxication on visual processing and oculomotor control. The carefully selected paradigms have yielded interesting findings that begin to map alcohol related impairments on different levels of oculomotor control. In addition, findings and discussions afford multiple approaches for further research that should help to achieve a deeper understanding of the effects of alcohol and its underlying mechanisms
Data set for "Primary-task activation during the processing of the secondary task in task-interruption situations"
No full textData set for the examination of the harmful effects of task interruptions on the performance in the primary task (i.e., resumption costs). Moreover, the data set can be used to examine whether the primary task is activated during the processing of the secondary task by analysing congruency effects in the secondary task.unknow
New insights into modality-compatibility effects in task switching
No full textDaily life quite frequently involves multitasking. We have to balance between different activities by shifting our attention between them or by simultaneously engaging in them according to our goal. In such a situation, we are exposed to a multimodal world. We have to perceive and process stimuli in different modalities and there are several possibilities for the modalities in which responses may be given. A large body of research is aimed at understanding the costs stemming from multitasking; however, in recent times, the fact that multitasking costs depend, at least partly, on sensory-motor modalities is receiving relatively more attention. The present dissertation is based on the previous findings of Stephan and Koch (2010, 2011, 2016), who implemented the task-switching paradigm wherein participants switched between an auditory-vocal (AV) and a visual-manual (VM) task in one condition and an auditory-manual (AM) and a visual-vocal (VV) task in another condition. Stephan and Koch (2010, 2011, 2016) observed larger switch costs with the AM-VV condition than with the AV-VM condition, and based on their results, they proposed the modality-compatibility account. Modality compatibility refers to the similarity between the stimulus modality and the modality of the anticipated sensory-response effects. For instance vocal responses produce auditory effects. It is assumed that there is a special linkage between sensory-motor modalities that comes from ideomotor (see Greenwald 1972) response-effect learning that leads to a tendency to bind the response modality to the most salient stimulus modality. Therefore, switching between modality-compatible tasks, the anticipated response-effect and the stimulus induced activation prime each other, whereas modality-incompatible tasks evoke between-task crosstalk due to a priming of the competing task. The aim of the present work is to investigate the modality-compatibility effects in task-switching from three research perspectives: structure, flexibility and plasticity. In the structural perspective, in Study I, we investigated the possible sensory-motor modality mapping combinations between stimuli in visual and auditory modalities, and responses in manual and vocal modalities in order to explore the structural boundaries of the modality-compatibility effects. We found that modality compatibility influences switch costs only when there is a variability between the stimulus and the response modality, but there are no relevant differences across modality compatibility when either the stimulus or the response modality is kept constant. Following the structural point of view, Study II indicated for the first time that modality compatibility also influences performance in a free choice situation by leading to a bias to produce modality compatible mappings. Importantly, even though the choices of response modalities were endogenous in Study II, modality compatibility still influenced switch costs as we have previously observed with forced-choice tasks. With regard to the flexibility perspective, in Study III, we conducted two experiments in order to explore the role of advance task preparation on modality-compatibility effects by introducing explicit cues. On the one hand, in both experiments, we found generally reduced modality-compatibility effects on switch costs, indicating that modality compatibility can be prepared with explicit cues and with sufficient time. On the other hand, the non-significant interaction between modality-compatibility effects on switch costs and the preparation effects suggests different underlying mechanisms. Finally, in the plasticity perspective, we introduced single-task practice in order to study the short-term practice effects on modality compatibility. In Study IV, we found a practice-related modulation of switch costs. After participants practiced modality compatible single-tasks, we observed that modality compatibility influenced switch costs; however, when participants practiced modality-incompatible single-tasks, modality compatibility had no relevant effect on switch costs. The findings of Study IV indicate that short-term associations by the practiced modality incompatible mappings could override the long-term modality-compatibility effects. In these four studies, we investigated modality-compatibility effects in task-switching based on the previous work of Stephan and Koch (2010, 2011, 2016). We explored the structural boundaries of modality-compatibility effects and found that modality compatibility represents compatibility across mappings and not within tasks at the level of stimulus or response modalities. The finding that using explicit cues reduces the modality-compatibility effects in the first place and the possibly different mechanisms underlying modality compatibility effects and active preparation facilitate to take into account processes that are needed to perform a task with several modalities. Finally, the reduced between-task crosstalk as a result of implementing short-term single-task practice is promising and provides an interesting perspective not only for research on modality compatibility but also for research investigating practice effects
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