Object recognition and the ventral "what stream". Used for a university course on visual perception.

1. What are you looking at?
Mechanisms of visual recognition.
Barbara Nordhjem
Visual Neuroscience Group
Laboratory of Experimental Ophthalmology
University Medical Center Groningen

2. Human recognition
• Gist of the scene at 7
images per second.
• Unpredictable random QuickTime™ and a
Sorenson Video 3 decompressor
sequence of images are needed to see this picture.
Potter 1971, 1975; Biederman 1972; Thorpe 1996 Movie by Jim DiCarlo

3. • Images change: object position, distance, pose, lighting
and background clutter. Yet we know where to attend and
what we are looking at.

4. Moving beyond V1
• What happens at the cellular level after
V1?

5. Simple Cells
Hubel & Wiesel, 1959, 1962, 1965,1968

6. Gradual more complex
preferred stimulus
Tanaka, 1996

7. Parallel increase in invariance properties (position and scale)
of neurons
Illustration from Rousselet et al., 2004

8. Pathways in the brain
• Lesions parietal lobe
(Newcombe, 1969)
• Ungerleider and Mishkin
(1982) lesions in monkeys.
Suggested regions
organized in pathways
• Goodale and Milner (1992)
distinguish between
perception and action
Figure by Mike Cohen

9. • The case of DF: visual form agnosia
• Carbon monoxide poisoning
• Lesion of lateral occipital cortex

10. Goodale et al., 1991

11. Aglioti et al., 1995

12. Are people attending to both
constellations when they grasp?
Patient (AT) with parietal lesions was
better grasping familiar than novel
objects – interaction of memory and
action control (Jeannerod et al.,
1994).
Aglioti et al., 1995

13. Modules in the brain
Processing areas with
the ventral pathway:
Faces, Objects, Places
Figure by Mike Cohen

14. Face and form agnosia
Some patients show a specific deficit for recognizing faces, others show
deficits for recognizing all other objects.
Faces and objects are processed in separate, perhaps non-overlapping,
brain areas.

15. The idea of functionally
specialized regions

16. Lateral Occipital (LO)
Malach, Levy, & Hasson, 2002 Grill-Spector et al., 1998

17. Levels of recognition
Gauthier et al., 1999, 2000

18. Visual awareness

19. Right FFA
Andrews et al., 2002

20. Two types of bistable figures
One-category
Two-category

21. One-category > Two-categories

22. Different ways of seeing

23. Peripheral and central vision
Levy et al., 2001

24. Form and texture
Cant & Goodale, 2007

25. Cant & Goodale, 2007

26. Representation in ventral areas
Freeman& Simoncelli, 2011

27. Fast saccade bias towards
faces, event for phase
scrambled images
Honey et al, 2008
Spatial scales: coarse and fine
representation
Olivia, 2007

28. More than one ventral pathway?

29. Summary
• Parallel increase in invariance to
position and scale of neurons from
V1 to IT
• Specialized information processing
• Dorsal and ventral pathways for
action and perception
• Keep in mind that the idea of
pathways and specialized regions
is simplified
visualneuroscience.nl