1. EDNE 016: Dynamic Vision
Chapter 6: Metacontrast and Motion Perception (pp ) Thomas Otto

2. A percept persists for some time after the termination of the stimulus
Visual persistence
A percept persists for some time after the termination of the stimulus
Visual persistence is about 120 ms under daylight

3. Motion smear
Burr (1980)
Moving objects should be perceived like in a photograph with a 125 ms shutter speed

4. Suppression of persistence
“The amount of motion smear is far less than may be expected from visual persistence”
Burr (1980)

5. A “moving stimulus” fulfills the definition of a metacontrast mask
Suppression of persistence & metacontrast
A “moving stimulus” fulfills the definition of a metacontrast mask
Suppression of persistence & metacontrast are similar from the perspective of PHENOMENOLOGY

6. Suppression of persistence & metacontrast are similar in:
Phenomenology
Suppression of persistence & metacontrast are similar in:
- Dependence on luminance - Spatial and temporal separation - Eccentricity

7. - motion compensation and “fusion” - lateral inhibition
Motion de-blurring models
Models of motion de-blurring can be viewed as models of metacontrast There are mainly two classes based on:
- motion compensation and “fusion” - lateral inhibition

8. Spatio-temporally oriented receptive fields
Motion compensation
Spatio-temporally oriented receptive fields
Burr, Ross & Morrone (1986)

9. The RECOD model Lateral inhibition
Purushothaman, Ogmen, Chen & Bedell (1998)

10. The RECOD model predicts extensive smear for isolated targets
The RECOD model & an isolated target
The RECOD model predicts extensive smear for isolated targets
Purushothaman, Ogmen, Chen & Bedell (1998)

11. The RECOD model & multiple targets
The motion smear is basically removed by the transient activity of nearby stimuli
Purushothaman, Ogmen, Chen & Bedell (1998)

12. An isolated target appears to be extensively smeared
Chen, Bedell & Ogmen (1995)

13. Confusing summary paragraph
“These findings provide evidence against models where motion plays a causal role in metacontrast”
Breitmeyer & Ogmen (2006)

14. Isolated target
A velocity of 10 deg/s corresponds to a SOA of about 5 ms given a target-mask separation of 200”

15. Confusing summary paragraph
“Metacontrast can improve the clarity of form perception by suppressing the smear of moving objects” “A careful parametric analysis shows that metacontrast and motion involve different mechanisms”
Breitmeyer & Ogmen (2006)

16. Summary
Suppression of persistence and metacontrast are similar from the perspective of STIMULI and PHENOMENOLOGY There might be ONE mechanism responsible for both phenomena!

17. Thanks for your attention!
The end
Thanks for your attention!

18. Transient and sustained activity

19. Experimental data vs. model prediction