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General and Experimental Psychology

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M.Sc. Anna Metzger



Justus-Liebig-Universität Gießen 
Fachbereich 06, Psychologie und Sportwissenschaft
Abteilung Allgemeine Psychologie
Otto-Behaghel-Strasse 10F
35394 Giessen

Campus: Building F1, Room 315
Phone: +49(0)641 / 99-26113
Email:


    Research interests


      The predominant focus of my research is sensory processing in haptic perception. I am interested in how the perceptual qualities which are mostly associated with the sense of touch are computed and represented in the brain. A good example to address these questions is research on softness perception. Softness is the subjective measure of an object's compliance (mm/N). Since there are no mechanoreceptors directly responding to compliance, it is commonly assumed that softness perception occurs by combining information about the displacement of an object's surface and the information about the force being applied to the object. Such information can be obtained from the cutaneous and kinesthetic afferent systems and in certain cases even from vision and audition. It is interesting how the information formed by different senses is integrated and whether there is a common crossmodal representation of softness. The perception of softness is also extended over considerable time spans and offers an insight into the integration of serial estimates. Furthermore, since several fingers might be involved in the exploration of softness it is interesting how the simultaneous estimates from multiple fingers are processed. On top, I am interested in the role of top-down signals in haptic perception and bottom-up haptic saliency as compared to visual saliency.

    Academic Degrees


    • 2008 - 2010: M.Sc. Cognitive Science at University of Osnabrück
      Thesis: An adaptive model of human attention based on hierarchical feature complexity

    • 2005 - 2008: B.Sc. Biology at Leibniz University Hannover

    Publications


    • Metzger, A. , & Drewing, K. (2016). Haptic Aftereffect of Softness. Haptics: Perception, Devices, Control, and Applications: 10th International Conference, EuroHaptics 2016, London, UK, July 4-7, 2016, Proceedings. Past sensory experience can influence present perception. We studied the effect of adaptation in haptic softness perception. Participants compared two silicon rubber stimuli, a reference and a comparison stimulus, by indenting them simultaneously with the index fingers of their two hands and decided which one felt softer. In adaptation conditions the index finger that explored the reference stimulus had previously been adapted to another rubber stimulus. The adaptation stimulus was indented 5 times with a force of >15 N, thus the two index fingers had a different sensory past. In baseline conditions there was no previous adaptation. We measured the Points of Subjective Equality (PSEs) of one reference stimulus to a set of comparison stimuli. We used four different adaptation stimuli, one was harder, two were softer and one had approximately the same compliance as compared to the reference stimulus. PSEs shifted as a function of the compliance of the adaptation stimulus: the reference was perceived to be softer when the finger had been adapted to a harder stimulus and it was perceived to be harder after adaptation to a softer stimulus. We conclude that recent sensory experience causes a shift of haptically perceived softness away from the softness of the adaptation stimulus. The finding that perceived softness is susceptible to adaptation suggests that there might be neural channels tuned to different softness values and softness is an independent primary perceptual quality.

    • Metzger, A. , & Drewing, K. (2015). Haptically perceived softness of deformable stimuli can be manipulated by applying external forces during the exploration. World Haptics Conference (WHC), 2015 IEEE. The perception of softness is the result of the integration of information provided by multiple cutaneous and kinesthetic signals. The relative contributions of these signals to the combined percept of softness was not yet addressed directly. We transmitted subtle external vertical forces to the exploring human finger during the exploration of deformable silicone rubber stimuli to dissociate the force estimates provided by the kinesthetic signals and the efference copy from cutaneous force estimates. This manipulation introduced a conflict between the cutaneous and the kinesthetic/efference copy information on softness. We measured Points of Subjective Equality (PSE) of manipulated references to stimuli which were explored without external forces. PSEs shifted as a linear function of external force in predicted directions - to higher compliances with pushing and to lower compliances with pulling force. We found relative contribution of kinesthetic/efference copy information to perceived softness being 23% for rather hard and 29% for rather soft stimuli. Our results suggest that an integration of the kinesthetic/efference copy information and cutaneous information with constant weights underlies softness perception. The kinesthetic/efference copy information seems to be slightly more important for the perception of rather soft stimuli.


    Teaching & Supervision


    • Course: Perception: Theory and Application (held in German: Wahrnehmung: Grundlagen und Anwedung) (SS16)

    • Master thesis: S. Bruckbauer: Top-down influences on sensory processing in somatosensory texture and shape perception. (SS16)
      cooperation with Project A4 in Collaborative Research Center "Cardinal Mechanisms of Perception"