Biomedical subjects

Ronald Hübner

Publications and source records attributed to Ronald Hübner.

9 recordsLinked to original sources

PubMed2006

Do the hemispheres differ in their preparation for global/local processing?

It has recently been suggested that hemispheric differences for global and local processing already occur in response to visual pre-cues that direct attention to a specific level. However, in the supporting studies cue information was confounded with the form of the cues. In order to dissolve the confound, we compared event-related brain potentials towards cues differing in form with those towards identically formed color cues. As a result, hemispheric differences were found only for the former cue type. The data thus show that the mere cue information does not produce hemispheric asymmetries associated with global/local target stimulus processing.

Adult↗

PubMed2006

Response-based strengthening in task shifting: evidence from shift effects produced by errors.

The hypothesis is introduced that 1 source of shift costs is the strengthening of task-related associations occurring whenever an overt response is produced. The authors tested this account by examining shift effects following errors and error compensation processes. The authors predicted that following a specific type of error, called task confusion, shift benefits instead of shift costs should result. A series of 3 experiments confirmed this prediction showing that task confusions produce shift benefits in subsequent trials (Experiment 1), even when the error is detected (Experiment 2). Moreover, only posterror processes that imply an error correction response produce shift costs (Experiment 3). These results additionally suggest that error detection cannot prevent errors from affecting subsequent performance.

Adult↗

PubMed2005

Response execution, selection, or activation: what is sufficient for response-related repetition effects under task shifting?

Repetition effects are often helpful in revealing information about mental structures and processes. Usually, positive effects have been observed when the stimuli or responses are repeated. However, in task shift studies it has also been found that response repetitions can produce negative effects if the task shifts. Although several mechanisms have been proposed to account for this interaction between task shifting and response repetition, many details remain open. Therefore, a series of four experiments was conducted to answer two questions. First, are motor responses necessary to produce response-related repetition effects, or is response activation sufficient? Second, does the risk of an accidental re-execution of the last response affect the repetition costs? The results show that response activation alone can produce repetition effects. Furthermore, the risk of accidental response re-execution largely modulates these effects.

Adult↗

PubMed2005

The integration of object levels and their content: a theory of global/local processing and related hemispheric differences.

This article presents and tests the authors' integration hypothesis of global/local processing, which proposes that at early stages of processing, the identities of global and local units of a hierarchical stimulus are represented separately from information about their respective levels and that, therefore, identity and level information have to be integrated at later stages. It further states that the cerebral hemispheres differ in their capacities for these binding processes. Three experiments are reported in which the integration hypothesis was tested. Participants had to identify a letter at a prespecified level with the viewing duration restricted by a mask. False reporting of the letter at the nontarget level was predicted to occur more often when the integration of identity and level could fail. This was the case. Moreover, visual-field effects occurred, as expected. Finally, a multinomial model was constructed and fitted to the data.

Adult↗

PubMed2005

Mixing costs in task shifting reflect sequential processing stages in a multicomponent task.

We investigated the hypothesis that mixing costs intask shifting reflect th e sequential selection of task components (e.g., stimulus categories) during task execution. This proposition was supported by Hübner, Futterer, and Steinhauser (2001), who showed that the amount of mixing costsdepends on the number of mixed task components (e.g., stimulus level and judgment). However, their results could also be explained by a task set selection account, because task components and task sets were confounded. In Experiments 1 and 2, we compared conditions in which either the number of task sets varied and the number of mixed task components was constant or vice versa. Only the number of mixed task components was predictive for the mixing costs. In Experiment 3, we replicated the additivity of mixing costs from level a ndjudgment mixing. Our results suggest thatthe mixingcosts reflect a selection strategy in which interference is reduced in a stepwise manner.

Adolescent↗

PubMed2004

On the role of response conflicts and stimulus position for hemispheric differences in global/local processing: an ERP study.

It is widely assumed that the local and global levels of hierarchical stimuli are processed more efficiently in the left and right cerebral hemispheres, respectively. However, corresponding effects were not observed under all circumstances. In ERP studies, they occurred more often with centrally presented stimuli than with laterally presented ones, whereas reaction-time studies revealed that a response conflict between the levels is relevant. The present study examines which of these two factors is more important by presenting conflicting and non-conflicting stimuli to the left or right visual field and recording ERPs as well as collecting behavioral data. If a central stimulus position is crucial, then no effects should show up. Contrary to this prediction, the expected hemispheric differences were observed in the behavioral data as well as in the later occurring (N2 and P3) ERP amplitudes. However, in all variables, the effects were more pronounced for conflicting stimuli. The results suggest that response conflicts are more important for obtaining hemispheric differences in global/local processing than a central stimulus presentation. This is interpreted in the way that hemispheric differences vary with respect to the stimulus representation that is needed to select a proper response.

Adult↗

PubMed2002

The influence of response competition on cerebral asymmetries for processing hierarchical stimuli revealed by ERP recordings.

It is widely accepted that the left and right hemispheres differ with respect to the processing of global and local aspects of visual stimuli. Recently, behavioural experiments have shown that this processing asymmetry strongly depends on the response competition between the global and local levels of a stimulus. Here we report electrophysiological data that underline this observation. Hemispheric differences for global/local processing were mainly observed for response-incompatible stimuli and were most prominent between 320 and 400 ms after stimulus onset. These results underpin the idea that hemispheric differences are more likely to show up when a more elaborated stimulus representation is needed for triggering the response, that is, when a response conflict has to be resolved.

Adult↗

PubMed2002

Can the spotlight of attention be shaped like a doughnut? Evidence from steady-state visual evoked potentials.

Visual attention enables observers to extract and process high-priority information in the visualfield. Controversy remains as to whether or not observers can ignore information that falls within the spatial beam of attention. We used an objective physiological measure, the steady-state visual evoked potential (SSVEP), to investigate this question. A stream of flickering small, uppercase letters was embedded in the center of a stream of large, uppercase letters. A unitary beam would result in no difference of the SSVEP amplitude elicited by the small letter stream when it was attended versus ignored (i.e., when subjects attended the large letter stream). Contrary to this prediction, SSVEP amplitude increased by almost 100% when the small letter stream was attended compared with when it was ignored. The results support the notion that the attentional spotlight can be formed like a doughnut, processing central information differentially depending on whether it is attended or ignored.

Adult↗

PubMed2002

The effect of response competition on functional hemispheric asymmetries for global/local processing.

It is widely assumed that the cerebral hemispheres differ in their capacity for processing the global and local levels of hierarchical stimuli. However, corresponding visual-field (VF) effects in response time studies did not show up under all circumstances. In the present article the role of response conflict between the levels for the occurrence of these effects is investigated. Three experiments with hierarchical letters are reported, in which the absolute and/or the relative interference between the stimulus levels was varied. It turned out that VF effects occurred only for conflicting stimuli and only when there was at least a certain amount of absolute interference, whereas variations of the relative interference had no effect in this respect. These results suggest that there is a qualitative relationship between interference and VF effects. A possible explanation is provided by the assumption that the hemispheres are functionally equivalent with respect to early stimulus representations, whereas they differ in their efficiency for integrating letter identity and stimulus level.

Adult↗