Biomedical subjects

Jörg Sangals

Publications and source records attributed to Jörg Sangals.

6 recordsLinked to original sources

PubMed2004

Time pressure effects on information processing in overlapping tasks: evidence from the lateralized readiness potential.

Information processing is impaired when two tasks are performed concurrently. The interference between the tasks is commonly attributed to structural bottlenecks or strategic scheduling of information processing. The present experiment investigated the effects of time pressure for the second of two responses on information processing in overlapping tasks by recording the lateralized readiness potential (LRP). Time pressure shortened the latency of the second response by diminishing the time devoted to motoric processing. In addition, task interference decreased under time pressure, which is probably due to the relatively early availability of the central bottleneck stage rather than to increased overlap of central stages. The LRP also provided direct evidence for an additional bottleneck following response selection, possibly due to supramodal refractoriness of response initiation.

Acoustic Stimulation↗

PubMed2004

Effects of additional tasks on language perception: an event-related brain potential investigation.

The authors investigated effects of task and overlapping processing load on semantic processing. In 3 experiments the brain potential component N400 was elicited by synonymous and nonsynonymous spoken noun pairs that were to be classified according to semantic relatedness. The time course of the N400 component to the nouns was delayed, and its amplitude was reduced when additional tasks had to be performed. The delay increased with temporal overlap and was more pronounced for language-related than for spatial additional tasks. Delays of N400 were also caused by a compatibility manipulation in the additional tasks. Theoretical accounts of the observed interference of overlapping tasks with language perception in terms of attentional shifts were discarded. Explanations in terms of resource sharing and single channel processing are discussed.

Adult↗

PubMed2004

The functional locus of the lateralized readiness potential.

The lateralized readiness potential (LRP) is considered to reflect motor activation and has been used extensively as a tool in elucidating cognitive processes. In the present study, we attempted to more precisely determine the origins of the LRP within the cognitive system. The response selection and motor programming stages were selectively manipulated by varying symbolic stimulus response compatibility and the time to peak force of an isometric finger extension response. Stimulus response compatibility and time to peak force affected response latency, as measured in the electromyogram, in a strictly additive fashion. The effects of the experimental manipulations on stimulus- and response-synchronized LRPs indicate that the LRP starts after the completion of response-hand selection and at the beginning of motor programming. These results allow a more rigorous interpretation of LRP findings in basic and applied research.

Adult↗

PubMed2003

Impairments of manual tracking performance during spaceflight are associated with specific effects of microgravity on visuomotor transformations.

In contrast to performance in cognitive tasks, tracking performance tends to deteriorate fairly consistently during spaceflight. We address the question whether this decrement results from specific effects of microgravity on motor control or from non-specific effects of the various other stressors present. In a case study we generalize the findings obtained with aiming movements, performed by the same cosmonaut with the same effectors as used for an unstable tracking task, to obtain hypotheses for specific changes of parameters of a simple model used to analyse tracking performance. Consistent with these hypotheses, we observed a reduction of limb stiffness in-flight, but a reduction of the tracking gain post-flight. The cross-task consistency of the observed changes does strongly suggest that the tracking impairment is at least partly caused by specific effects of microgravity on motor control, in particular by a mis-calibration of muscular forces which likely results from an underestimation of masses due to weightlessness.

Ergonomics↗

PubMed2003

Are fingers special? Evidence about movement preparation from event-related brain potentials.

Ulrich, Leuthold, and Sommer (1998) suggested that movement preparation at the level of the motor cortex, as indexed by the lateralized readiness potential (LRP), proceeds in a strongly hierarchical fashion, where parameters other than response hand are prepared only if all the movement parameters are known. These conclusions were based on an experiment where a precue provided information about response hand, direction of finger movement, and movement force. To assess the generality of these findings, we replaced the force parameter with response finger. LRP indicated that preparation of the required finger is possible even when preliminary information is incomplete. Therefore, movement preparation appears to follow different rules when anatomical relationships (hand and finger) are concerned as compared to functional parameters like movement direction. On the other hand, at a limb-unspecific level, as indicated by the contingent negative variation, we confirmed evidence for parallel programming of all movement parameters.

Adult↗

PubMed2002

Influences of presentation mode and time pressure on the utilisation of advance information in response preparation.

An important approach to the investigation of movement selection and preparation is the precuing paradigm where preliminary information about a multidimensional response leads to reaction time benefits which are positively related to the amount of precue information. This so-called precuing effect is commonly attributed to data-limited preparatory motoric processes performed in advance of the response signal. By means of recording the lateralised readiness potential (LRP), the present experiments investigated whether the precuing effect could be explained also by variables that affect strategic utilisation of stimulus-conveyed information. Experiment 1 presented fully and partially informative precues either in mixed or blocked mode. Experiment 2 exerted various degrees of time pressure to the different precue conditions. In both experiments, the precuing effect on reaction times and the LRP was fully preserved, refuting the notion that the sensitivity of the LRP to the amount of preliminary information merely reflects differential precue utilisation. As a major finding, time pressure increased the LRP amplitude during response preparation which is consistent with the view that response strategies generally influence movement preparation on a motoric level.

Adult↗