Dr Mark EDWARDS

PhD

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Research and Supervision Interests
Current Teaching
Research Students
Qualifications
Selected Publications

Our sense of vision is fundamental to our ability to interact with the world. Additionally, a great deal of our understanding of how the brain functions is based on our knowledge of how it processes visual information. The aim of my research is to further our understanding of the workings of the human visual system, with an emphasis on how various visual pathways interact at different levels in the brain. While I am interested in all aspects of visual processing, my research to date has mainly focused on motion, stereopsis and face processing.

Motion Processing

Many of the objects of interest to us are in motion, so it is not surprising that the extraction of visual motion is one of the tasks that the visual system is specialised for. Indeed, a major subsystem within the brain is dedicated to motion processing. My research has focused on a number of aspects of motion processing, including determining how: different visual pathways interact at different levels in the brain; motion (dorsal pathway) and form (ventral pathway) signals interact; the sensitivity of the visual system to optic-flow information (patterns of retinal motion produced by motion through an environment); optic-flow information affects perceived stereoscopic depth; speed information is processed and how form information affects the perception of motion, transparent motion signals are processed and linking psychophysical performance to the know properties of cortical cells.

Stereoscopic Depth Processing

Having two, horizontally displaced, forward looking eyes (as opposed to laterally placed eyes) results in each eye receiving a slightly different view of the world. The visual system is able to generate a percept of depth by comparing these different images. My research on stereopsis has focused on: the characteristics of the transient stereo-system (which performs the initial extraction of depth information); the interaction of depth information in forming a coherent depth percept and the interaction of different visual pathways in depth processing.

• coordinator PSYC3011 (Perception)
• coordinator PSYC2008 (Visual Perception and Cognition)

John Greenwood (PhD)
Processing multiple motion signals within the human visual motion hierarchy.

Anthony Gates (PhD)
How motion signals affect perceived location

Conrad Buffier (Hons)
What determines visual acuity, retinal or perceived size ?

Brand Steyn (Hons)
Interaction of the On-Off and speed tuned channels at the local-motion-pooling level

Kanupriya Kalia (Hons)
Why does adaptation to transparent motion result in a unidirectional motion aftereffect ?

Hugh Dennett (Hons)
Does the visual system process faces and high-level in the same manner ?

Some Previous Students

Denisa Goldhammer (Hons)
The orientation tuning of face-sensitive cells within the human brain, as assessed by adaptation aftereffects

John Brown (PhD - Clinical, with Dr Ward & Dr. McKone)
A long-term ecstasy-related change in visual perception.

Monique Crane (Hons)
Do motion streaks facilitate motion processing ?

Keli Wainwright (Hons)
Determining the pre-attentive just noticeable difference for motion direction.

David Lemke (Hons)
A contrasting view of visual search: The role of physiological channels in grouping.

Leslie Grainger (Hons)
Global speed processing: Evidence for a relative motion analysis.

Academic and Research Background

Bachelor of Engineering (Mechanical) (Hons). University of Queensland. 1985

Bachelor of Science (Psychology) (Hons) Australian National University. 1990

Ph.D. (Psychology) University of Melbourne, 1995

Post-Doctoral Research Fellow, NTT Basic Research Laboratories, Japan November 1994 to December 1995

Post-Doctoral Research Fellow, University of California at Berkeley, USA. December 1995 to May 2001

Brown, J., Edwards, M., Ward, J., & McKone, E. (2007). A long-term ecstasy related change in visual perception. Psychopharmacology, In Press

Greenwood, J.A., & Edwards, M. (2007). An oblique effect for transparent-motion detection caused by variation in global-motion direction-tuning bandwidths. Vision Research, 1411-1423.

Robbins, R., McKone, E., & Edwards, M. (2007). Aftereffects for face attributes with different natural variability: adaptor position effects and neural models. Journal of Experimental Psychology: Human Perception and Performance, 33(3), 570-592.

Edwards, M., & Crane, M.F. (2007). Motion streaks improve motion detection.Vision Research, 828-833.

Edwards, M. & Ibbotson, M.R. (2007). Sensitivity to large-field optic-flow: Relative sensitivities to different directions and speeds. Perception, 36(1), 113-124.

Edwards, M. & Grainger, L. (2006). Effect of signal intensity on perceived speed. Vision Research, 2728-2734.

Greenwood, J.A. & Edwards, M. (2006). Pushing the limits of transparent-motion detection with binocular disparity. Vision Research, 2615-2624.

Greenwood, J.A. & Edwards, M. (2006). An extension of the transparent-motion detection limit using speed-tuned global-motion systems. Vision Research, 46,1440-1449.

McKone, E., Aitkin, A., & Edwards, M. (2005). Categorical and coordinate relations in faces, or is it Fechner’s Law and face space instead ? Journal of Experimental Psychology: Human Perception and Performance, 31(6), 1181-1198.

Edwards, M., & Greenwood, J.A. (2005). The perception of motion transparency: A signal-to-noise limit. Vision Research, 45, 1877-1884.

Edwards, M., & Nishida, S. (2004). Contrast reversing global motion stimuli reveal local interactions between first and second-order motion signals. Vision          Research, 44, 1941-1950.

Edwards, M., & Badcock, D.R. (2003). Motion distorts perceived depth. Vision Research, 43, 1799-1804.

Trewhella, J., Edwards, M., & Ibbotson, M.R. (2003). Sensitivity to the Acceleration of looming stimuli. Clinical and Experimental Ophthalmology, 31(3), 258-261.

Sato, M., Edwards, M., & Schor, C.M. (2001). Envelope size-tuning for transient disparity vergence. Vision Research, 41, 1695-1707.

Schor, C.S., Edwards, M., & Sato, M. (2001). Envelope size tuning for stereo-depth perception of small and large disparities. Vision Research, 41, 2555-2567.

Zhang, Z., Edwards, M. & Schor, C.M. (2001). Spatial Interactions Minimize Relative Disparity Between Adjacent Surfaces. Vision Research,41, 2995-3007.

Edwards, M., Pope, D.R., & Schor, C.M. (2000). First- and second-order processing in transient stereopsis. Vision Research, 40, 2645-2652.

Edwards, M. & Schor, C.M. (1999). Depth aliasing by the transient stereo-system. Vision Research, 39, 4333-4340.

Edwards, M., & Nishida, S. (1999). Global-motion transparency: No direction-specific masking. Vision Research, 39, 2239-2249.

Edwards, M., Pope, D.R., & Schor, C.M. (1999). Orientation tuning of the transient-stereopsis system. Vision Research, 39, 2717-2727.

Pope, D.R., Edwards, M. & Schor, C.M. (1999). Extraction of depth from opposite-contrast stimuli: Transient system can, sustained system can't. Vision Research, 39, 4010-4017.

Pope, D.R., Edwards, M. & Schor, C.M. (1999). Orientation and luminance polarity tuning of the transient-vergence system. Vision Research, 39, 575-584.

Edwards, M. & Badcock, D.R. (1998). Global-motion signal-discrimination performance. Vision Research, 38, 3051-3056.

Edwards, M., Badcock, D.R. & Smith, A.T. (1998). Independent speed-tuned global-motion systems. Vision Research, 38, 1573-1580.

Edwards, M., Pope, D.R. & Schor, C.M. (1998). Luminance-contrast and spatial-frequency tuning of the transient-vergence system. Vision Research, 38, 705-717.

Schor, C.M., Edwards, M. & Pope, D.R. (1998). Spatial-frequency tuning of the transient-stereopsis system. Vision Research, 38, 3057-3068.

Nishida, S., Edwards, M., & Sato, T. (1997). Simultaneous motion contrast across space: Involvement of second-order motion ? Vision Research, 37, 199-214.

Nishida, S., Ledgeway, T. & Edwards, M. (1997). Dual multiple-scalar processing for motion in the human visual system. Vision Research. 37, 2685-2695.

Edwards, M., & Badcock, D.R. (1996). Global motion perception: Interaction of colour and luminance inputs. Vision Research, 36, 2423-2432.

Edwards, M., Badcock, D.R., & Nishida, S. (1996). Contrast sensitivity of the motion system. Vision Research, 36, 2411-2422.

Edwards, M., & Badcock, D.R. (1995). Global motion perception: No interaction between the first- and second-order motion pathways. Vision Research, 35, 2589-2602.

Edwards, M., & Badcock, D.R. (1994). Global motion perception: Interaction of the On and Off pathways. Vision Research, 34, 2849-2858.

Edwards, M., & Badcock, D.R. (1993). Asymmetries in the sensitivity to motion in depth: A centripetal bias. Perception, 22, 1013-1023.

Stuart, G.W., Edwards, M., & Cook, M.L. (1992). Colour inputs to random-dot stereopsis. Perception, 21, 717-729.