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  • Author or Editor: Georg Meyer x
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In: Sprache und Literatur

Visual motion signals are an important source of self-motion information that are used in postural control. Bronstein and Buckwell (Exp. Brain Res. 113, 243–248, 1997) showed that postural reactions to visual motion are not rigid responses to optokinetic stimulation but specific responses appropriate for stabilising posture in natural circumstances: body sway, for instance, was abolished when participants fixated a static object in front of a laterally moving background, which in itself induced sway. We test whether haptic and auditory as well as visual fixation points reduce body sway induced by a background that either moved left/right or forward/back on a large (3 × 7 m) 3D visual display. 10 participants were asked to respond when a fixation target, whichs was presented either on a background or foreground, changed colour. Body sway was measured using a VICON motion tracking system. We tested three conditions that replicated Bronstein and Buckwell’s original study and show that body sway, induced by lateral motion of the background is abolished when participant fixate on a (virtual) foreground object. We extended their study by showing that 3D motion (looming/receding background) has a similar effect to lateral motion and to show that body sway can be effectively reduced by providing either auditory (a loudspeaker emitting a white noise) and haptic (participants lightly touch a tripod with their index finger) cues. Our findings show that postural control draws auditory and haptic as well as visual cues. The findings are relevant to the design of virtual reality systems and provide a method for objective measures of presence in virtual environments.

In: Seeing and Perceiving

An image reflected in a mirror may appears in the visual field in a location opposite to the physical location of the object in the environment, in particular it may appear on the right when the object is on the left and vice versa. Through experience people have knowledge that reflections are not real objects an also that they are informative about object locations. We tested the importance of this knowledge in a simple task in which participants had to respond to a visual stimulus (light from an LED) that could appear in the right or left visual field. Participants had to respond with the contralateral hand, i.e., they had to press the right button if the light was on the left and vice versa. An irrelevant sound could also originate from the left or the right side. To avoid different bouncing of the sound the mirror condition was compared to a glass condition so that the solid surfaces were identical in size. When light and sound had the same spatial origin responses were faster, however this was only true as long as the light was seen though a glass and not seen reflected in a mirror. We conclude that participants are influenced by the knowledge about the origin of a light when when this information is irrelevant for their task.

In: Seeing and Perceiving

There is interest in how pilots perceive simulator fidelity and rate self-performance in virtual reality flight training. Ten participants were trained to perform a target tracking task in a helicopter flight simulation. After training objective performance, the median tracking error, was compared to subjective self-evaluations in a number of flying conditions where the cues available to our pilots were manipulated in a factorial design: the simulator motion platform could be active or static, audio cues signalling the state of the turbine could be those used during training, non-informative, or an obviously different but informative ‘novel’ sound. We tested participants under hard and easy flying conditions. Upon completion of each test condition, participants completed a 12-statement Likert-scale with items concerning their performance and helicopter simulator fidelity. Objective performance measures show that flight performance improved during training and was affected by audio and motion cues. The subjective data shows that participants reliably self-evaluated their own performance and simulator fidelity. However, there were instances where subjective and objective measures of performance or fidelity did not correlate. For example, although participants rated the ‘novel’ turbine sound as having low fidelity, it behaviourally caused no difference with respect to the turbine sound used in training. They were also unable to self-evaluate outcome of learning. We conclude that whilst subjective measures are a good indicator of self-performance, objective data offers a valuable task-oriented perspective on simulator fidelity.

In: Seeing and Perceiving

Previous functional magnetic resonance imaging (MRI) found various brain areas in the temporal and occipital lobe involved in integrating auditory and visual object information. Fiber tracking based on diffusion-weighted MRI suggested neuroanatomical connections between auditory cortex and sub-regions of the temporal and occipital lobe. However, the relationship between functional activity and white-matter tracks remained unclear. Here, we combined probabilistic tracking and functional MRI in order to reveal the structural connections related to auditory–visual object perception. Ten healthy people were examined by diffusion-weighted and functional MRI. During functional examinations they viewed either movies of lip or body movements, listened to corresponding sounds (phonological sounds or body action sounds), or a combination of both. We found that phonological sounds elicited stronger activity in the lateral superior temporal gyrus (STG) than body action sounds. Body movements elicited stronger activity in the lateral occipital cortex than lip movements. Functional activity in the phonological STG region and the lateral occipital body area were mutually modulated (sub-additive) by combined auditory–visual stimulation. Moreover, bimodal stimuli engaged a region in the posterior superior temporal sulcus (STS). Probabilistic tracking revealed white-matter tracks between the auditory cortex and sub-regions of the STS (anterior and posterior) and occipital cortex. The posterior STS region was also found to be relevant for auditory–visual object perception. The anterior STS region showed connections to the phonological STG area and to the lateral occipital body area. Our findings suggest that multisensory networks in the temporal lobe are best revealed by combining functional and structural measures.

In: Seeing and Perceiving
Medien/Lektüre
Ein Paderborner Jesuit am Kaiserhof in Wien
Author: Georg Korting
Der Paderborner Jesuit Vitus Georg Tönnemann wirkte seit 1694 in Wien und war von 1711 bis 1740 Beichtvater und persönlicher Berater Kaiser Karls VI. In der Einleitung ordnet der Autor den Lebensgang Pater Tönnemanns in die Geschichte des Jesuitenordens ein. Auf einen Lebensabriss folgt die kommentierte Vita Tönnemanns von W. Thöne (1935). Vor diesem Hintergrund werden dann einzelne Aspekte seines Bildungsganges und seiner einflussreichen kirchenpolitischen Tätigkeiten näher analysiert: seine Position als oberster Militärkaplan, seine Kontakte und Verhandlungen mit Herzog Karl Leopold von Mecklenburg-Schwerin, Herzog Anton Ulrich und Elisabeth Christine von Braunschweig-Wolfenbüttel, Papst Clemens XI. und Zinzendorf. Das Kap. über die Prozesse um Büren erörtert die Behauptung einer Handschrift, nach welcher der Kurfürst von Brandenburg auf Grund von Tönnemanns Einfluss auf Büren verzichtete, um (1701) die Königs würde erhalten zu können. Der Anhang enthält 12 z. T. erstmalig übersetzte Quellen, u. a. mehrere Nekrologe.