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General and Experimental Psychology









Research group
Perception and Action

Graduate school

Sensory-Motor Decision-Making


Our research is directed at understanding information processing in the visual system during visual and motor judgements. Our laboratory in Gießen includes set-ups for studies on visual perception (color vision and perception of natural scenes) and for studies on sensori-motor coordination, including state-of-the-art equipment for eye-tracking (EyeLinkII, DPI Eyetracker), motion analysis (Optotrak-3020 System, Zebris Tracking System), and for the manipulation of visual-proprioceptive information (PHANToM- force feedback device).

We currently primarily use psychophysical methods, but future research questions are also directed at studying the neural correlates of sensori-motor control. Collaborations have recently been established within the joint graduate program Neuronal representation and action control with the Department of Neurophysics and Departement of Experimental and Clinical Biopsychology at the nearby Philipps-Universität Marburg.

In addition, our lab participates in national and international co-operations directed at studying the behavioral and neural aspects of sensori-motor control (Research Training Network on Perception for Recognition and Action funded by the European Commission; Forschungsverbund MODKOG, funded by the BMBF).

Research Areas

Color Vision

Prof. Karl Gegenfurtner, Ph.D. , Dr. Thorsten Hansen, Dipl.-Psych. Lars Pracejus, & Dipl.-Biol. Sebastian Walter

The perception of color is a central component of primate vision. Colour facilitates object perception and recognition, and has an important role in scene segmentation and visual memory. Despite the long history of colour vision studies, much has still to be learned about the physiological basis of colour perception. Recent studies are beginning to indicate that colour is processed not in isolation, but together withinformation about luminance and visual form to achieve a unitary and robust representation of the visual world.

Perception and eye movements in natural scenes

Dipl.-Inf. Jan Drewes, M.A. Psych. Brian White

We study the principles underlying the selection of fixation points under natural viewing conditions. We study fixation patterns and saccadic latencies of human subjects viewing under natural images and videos of natural scenes and ask how stimulus features like contrast, color and spatial frequency content interacts with the top-down mediated expectations.

Sensory-motor decision making (Emmy Noether-Nachwuchsgruppe)

Dr. Knut Drewing, Dipl.-Ing. (FH) Martin Stritzke, Dr. Julia Trommershäuser

This research combines theoretical and experimental methods to investigate visuo-motor strategies during the planning and execution of goal-directed (arm) movements under risk. In the experiments, we study human movement planning in environments where there are explicit gains and losses associated with the outcomes of actions and compare human performance to a model of optimal performance based on statistical decision theory. The model comprises approaches of motor control,statistical and Bayesian decision theory and is based on the idea that goal-directed movements reflect a movers choice under the constraints of the perceptual and motor system.

Smooth pursuit eye movements

Dr. Doris Braun, Prof. Karl Gegenfurtner, Ph.D. , PD Dr. Dirk Kerzel, Dipl.-Psych. Lars Pracejus, Dipl.-Psych. Miriam Spering, Dipl.-Psych. Nathalie Ziegler

If an object of interest moves in our environment, we are able to elicit smooth pursuit eye movements that keep the image of the moving object stationary on our fovea. The processing of visual motion underlying the execution of smooth pursuit eye movements is very similar to the processing underlying the perception of visual motion. perception and pursuit share some of the neural signals that are a result of objects moving across the retina. On the other hand, pursuit has many neural connections that are not part of the perceptual system. In addition, cognitive factors including attention, prediction and learning have been demonstrated to influence the execution of smooth pursuit. Our experimental approach comprises psychophysics measurements under simultaneous tracking of eye-movements to separate the underling neuronal mechanisms driving perception or the ocolumotor response.

Visually guided motor behavior

Dr. Volker Franz, Dipl.-Psych. Denise de Grave, Dipl.-Psych. Constanze Hesse, Dipl.-Psych. Jutta Billino

We investigate the complex mechanisms involved in interactions of humans with the environment. The versatility of the human visuo-motor system can be seen in the ease with which we perform everyday tasks as reaching and grasping for objects under varying visual input. For example, we can easily grasp fragile objects like eggs (we might even learn to joggle with them), or we might learn to adapt quickly to the distortions introduced by wearing left-right reversing prisms, etc. On the other side, it is still very difficult to devise technical systems which are capable of only a subset of the capabilities of the human motor system.

One of the questions which we have been studying very intensively during the last years is whether the visual guidance of motor behavior is achieved by different processes (and neuronal substrates) as our conscious (visual) perception. Studies on neurological patients suggest such a division of labor in the human brain and it was suggested that this dissociation between vision-for-action and vision-for-perception can also be found in healthy humans. Support for this view came from studies which found that grasping is less affected by visual illusions than perception. Our results, to the contrary, suggest that the motor system uses very similar processes and neuronal signals as visual perception. This suggests that the visual brain is more coherent than currently proposed by a number of theories in visual neuroscience.

We use an Optotrak 3020 system to measure precisely position and timing of grasping and pointing movements. To control the Optotrak we use a specifically designed Matlab Toolbox (or C++).

Justus-Liebig-Universität  |  PsychologieAbteilungen