Supervisor: Alan Johnston (School of Psychology)
Co-supervisor: Neil Roach (School of Psychology)

Description:

The aim of this project will be to explore the stage of motion processing in which local estimates of direction and speed of motion are combined to represent global motion patterns. This is thought to occur at the level of V5/MT and MST in the primate and human brain. These global motion patterns may reflect simple translations and rotations or the more complex, non-rigid, but constrained natural patterns generated by facial movement, flocking birds, liquid flow, flame or wind-blown vegetation. Two questions will be addressed here. Is there an explicit representation of local velocity on which subsequent computations are based or can motion patterns be encoded without going through this intermediate representation. The second question is, if local velocities are combined, which of the various strategies that have been proposed, vector average, intersections of constraints or harmonic vector average best predicts existing data. Models will be refined by the process of forming competing predictions through computational simulation and testing the predictions using visual psychophysics. Candidate models will also be evaluated by their effectiveness in coping with difficult cases presented by complex natural motion.

Reading:

• Johnston A and Scarfe P (2013) The role of the harmonic vector average in motion integration. Front. Comput. Neurosci. 7:146. doi: 10.3389/fncom.2013.00146
• Nishida, S., Kawabe, T., Sawayama, M., & Fukiage, T. (2018). Motion Perception: From Detection to Interpretation. Annual Review of Vision Science, 4(1), 501–523. http://doi.org/10.1146/annurev-vision-091517-034328
• Rider, A. T., Nishida, S., & Johnston, A. (2016). Multiple-stage ambiguity in motion perception reveals global computation of local motion directions. Journal of Vision, 16(15), 7–11. http://doi.org/10.1167/16.15.7

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