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Biomedical subjects

Bernhard Hommel

Publications and source records attributed to Bernhard Hommel.

44 records · Page 3Linked to original sources
PubMed2003

Symbolic control of visual attention: The role of working memory and attentional control settings.

This study examined how 1 symbol is selected to control the allocation of attention when several symbols appear in the visual field. In Experiments 1-3, the critical target feature was color, and it was found that uninformative central arrows that matched the color of the target were selected and produced unintentional shifts of attention (i.e., involuntary, initiated slowly, producing long-lasting facilitatory effects). Experiment 4 tested whether such selection is the result of an attentional filter or of a competition bias due to a match of incoming information against integrated object representations stored in working memory. Here, the critical feature was shape and color was irrelevant, but matching color arrows were still selected. Thus, features of objects in working memory will bias the selection of symbols in the visual field, and such selected symbols are capable of producing unintentional shifts of attention. ((c) 2003 APA, all rights reserved)

Adult↗
PubMed2002

Control of stimulus-response translation in dual-task performance.

In contradiction to stimulus-response- (S-R-) translation bottleneck models of dual-task control, stimulus processing in a primary task is affected by its compatibility with the response in a secondary, later performed task (Hommel, 1998a)- an indication of parallel S-R translation. Here we show that this backward-compatibility effect is independent of working-memory load, whether this is induced by an extra memory task (Experiment 1) or by increasing the number of S-R alternatives in the primary task (Experiment 2). However, backward effects occur even when the secondary task is no longer carried out (Experiment 3) and they are strongly affected by the inconsistency of previously used S-R mappings (Experiment 4). These findings suggest that S-R translation is (or can be) capacity-independent and automatic even under multiple-task conditions, and that it is mediated by direct S-R associations that emerge after only little practice.

Adult↗
PubMed2002

Consciousness and control in task switching.

Participants were required to switch among randomly ordered tasks, and instructional cues were used to indicate which task to execute. In Experiments 1 and 2, the participants indicated their readiness for the task switch before they received the target stimulus; thus, each trial was associated with two primary dependent measures: (1) readiness time and (2) target reaction time. Slow readiness responses and instructions emphasizing high readiness were paradoxically accompanied by slow target reaction time. Moreover, the effect of task switching on readiness time was an order of magnitude smaller then the (objectively estimated) duration required for task preparation (Experiment 3). The results strongly suggest that participants have little conscious awareness of their preparedness and challenge commonly accepted assumptions concerning the role of consciousness in cognitive control.

Analysis of Variance↗
PubMed2002

Linking actions and their perceivable consequences in the human brain.

Voluntary action is goal-directed and therefore depends on the ability to learn associations between movements and their perceivable consequences. The neural substrate of this ability was investigated with H2(15O) positron emission tomography (PET). Healthy adults first learned that self-initiated keypresses were consistently followed by certain tones (i.e., action effects). During PET imaging, participants listened to varied ratios of action-effect tones and neutral tones without performing any movement. The caudal supplementary motor area and the right hippocampus increased their activity with the frequency of action-effect tones, suggesting that both cortical areas play a role in linking the consequences of an action and the action itself. This integration process represents a highly flexible mechanism that helps to promote the learning, automatization, and control of voluntary

Acoustic Stimulation↗
PubMed2002

Responding to object files: automatic integration of spatial information revealed by stimulus-response compatibility effects.

Spatial information is assumed to play a central, organizing role in object perception and to be an important ingredient of object representations. Here, evidence is provided to show that automatically integrated spatial object information is also functional in guiding spatial action. In particular, retrieving nonspatial information about a previewed object facilitates responses that spatially correspond to this object. This is true whether the object is still in sight or has already disappeared. So, forming an object representation entails the integration and storage of action-related information concerning the action that the object affords.

Adult↗
PubMedDate not supplied

Development of the acquisition and control of action-effect associations.

Voluntary action is anticipatory and, hence, must depend on associations between actions and their perceivable effects. We studied the acquisition of action-effect associations in 4-5-vs. 7-year-old children. Children carried out key-pressing actions that were arranged to produce particular auditory effects. In a subsequent test phase, children were to press keys in response to the previous effect sounds, with the sound-key mapping being either consistent or inconsistent with previous key-sound practice. As the processes underlying voluntary action controls are known to significantly improve between 4 and 7 years of age, it was expected that younger children were more prone to automatic effects of acquired sound-key associations. This hypothesis was confirmed, but reaction times and accuracy measures showed different and dissociable patterns. Four-year-olds but not 7-year-olds were more likely to commit an error--i.e., to perform a sound-compatible rather than the correct action--if the sound-key mapping was inconsistent with previous practice. This effect strongly depended on previous practice, suggesting that it reflects long-term learning. In contrast, reaction time effects of mapping consistency did not depend on previous experience but only on the consistency between stimulus and action effect in the present task. Taken altogether, the results suggest that children acquire response-effect associations automatically and that younger children are more likely to suffer from frequent goal neglect; i.e., they tend to forget the current action goal, so that their behavior is dominated by automatic, stimulus-triggered response tendencies.

Age Factors↗