chapter 6: metacontrast and motion perception (pp. 219-233 ) thomas otto
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EDNE 016: Dynamic Vision. 23.01.2007. Chapter 6: Metacontrast and Motion Perception (pp. 219-233 ) Thomas Otto. Visual persistence. A percept persists for some time after the termination of the stimulus. Visual persistence is about 120 ms under daylight. Motion smear. Burr (1980). - PowerPoint PPT PresentationTRANSCRIPT
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Chapter 6: Metacontrastand Motion Perception (pp. 219-233 )
Thomas OttoEDNE 016: Dynamic Vision23.01.2007
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Visual persistenceA percept persists for some time after the termination of the stimulusVisual persistence is about 120 ms under daylight
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Motion smearBurr (1980)Moving objects should be perceived like in a photograph with a 125 ms shutter speed
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Suppression of persistenceThe amount of motion smear is far less than may be expected from visual persistenceBurr (1980)
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Suppression of persistence & metacontrastA moving stimulus fulfills the definitionof a metacontrast mask Suppression of persistence & metacontrast are similar from the perspective of PHENOMENOLOGY
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PhenomenologySuppression of persistence & metacontrast are similar in: - Dependence on luminance
- Spatial and temporal separation
- Eccentricity
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Motion de-blurring modelsModels of motion de-blurring can be viewed as models of metacontrast
There are mainly two classesbased on: - motion compensation and fusion
- lateral inhibition
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Motion compensationSpatio-temporally oriented receptive fieldsBurr, Ross & Morrone (1986)
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Lateral inhibitionThe RECOD modelPurushothaman, Ogmen, Chen & Bedell (1998)
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The RECOD model & an isolated targetPurushothaman, Ogmen, Chen & Bedell (1998)The RECOD model predicts extensive smearfor isolated targets
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The RECOD model & multiple targetsPurushothaman, Ogmen, Chen & Bedell (1998)The motion smear is basically removed by the transient activity of nearby stimuli
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Isolated targetAn isolated target appears to be extensively smearedChen, Bedell & Ogmen (1995)
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Confusing summary paragraphThese findings provide evidence against models where motion plays a causal role in metacontrastBreitmeyer & Ogmen (2006)
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Isolated targetA velocity of 10 deg/scorresponds to a SOA of about 5 ms given a target-mask separation of 200
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Confusing summary paragraph Metacontrast can improve the clarity of form perception by suppressing the smear of moving objects
A careful parametric analysis shows thatmetacontrast and motion involve different mechanisms
Breitmeyer & Ogmen (2006)
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SummarySuppression of persistence and metacontrast are similar from the perspective of
STIMULI and PHENOMENOLOGY
There might be ONE mechanism responsible for both phenomena!
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The end Thanks for your attention!
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Transient and sustained activity
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Experimental data vs. model prediction