Introduction

1. Introduction Applied Perception for Visual Computing Jehee Lee A lot of slides stolen from AditiMajumder

2. Instructors • Carol O’Sullivan • Professor, Trinity College Dublin • Sabbatical visit at SNU starting from Oct 2012 • Computer graphics, Computer animation, Human perception, Eye movements • Office/Phone will be available soon • Jehee Lee • Professor, Seoul National University • Computer graphics, Computer animation, Human movements, Biomechanics, Robotics • Office: 302-325 • Phone: 1845

3. Course Introduction • Understanding and applying principles of human perception • We are particularly interested in visual computing • Computer graphics, computer vision, virtual reality, image processing, visualization, experimental psychology, neuroscience • Access and enhance computer-generated scenes, animations, and virtual environments. • The course will be delivered via a combination of lectures, guest speakers, and student presentations

4. Recommended references • Visual Perception from a Computer Graphics Perspective, W. B. Thompson, R. W. Fleming, S. H. Creem-Regehr, J. K. Stefanucci, CRC Press. • Vision and Art: The Biology of Seeing, Margaret Livingstone, Abrams.

5. Grading Policy • Course participation, presentation: 50% • Term project or term paper: 50%

6. What is Perception? • Sensory experience of the world around us • Involves • Recognition of environmental stimuli • Actions in response to these stimuli • Five senses: touch, sight, smell, taste, hear • Proprioception • A set of senses involving the ability to detect changes in body positions and movements

7. You are easily fooled

8. Perceptual Process • Cycles of Environment, Perception, and Action • Continual • You do not spend much time thinking about the actual process • Unconscious, Automatic • Eg) Transforminglight on your retinas into visual image

9. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

10. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

11. Environmental Stimulus • Anything in our environment that we can perceive • Can be anything we can sense • see, hear, touch, smell, taste, or • the sense of proprioception

12. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

13. Attended Stimulus • A part of the environmental stimulus • Focuses attention on this stimulus

14. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

15. Stimulus on receptors • The attended stimuli excites the receptors • For example • Visual stimulus formed as an image on the retina • Sound changes pressure to affect the ear drum • Note • We do not perceive the image on the retina • It is just one of the initial steps of the process

16. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

17. Transduction • Transformation of one form of energy to other • Environmental energy transformed to electrical energy • The image on the retina generates electrical signals in the tens and thousands receptors of the eye Photoreceptor cells

18. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

19. Neural processing • Neurons are elements of nervous system • Interconnected together • Processing of the electrical energy by the neurons while they travel through them • This changes the electrical energy in various ways

20. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

21. Perception • Conscious sensory experience • Electric energy transforms in brain to some experience • Is this the end of perception? • Recognition and action are important outcomes of the perceptual process

22. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

23. Recognition • Identifying the experience as something • Known • Similar to some experience before • Placing objects in meaningful categories • Recognition and Perception are two separate process • The Man who Mistook his Wife for a Hat • By Oliver Sacks • The case study of a man with visual agnosia

24. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

25. Action • Goal of perception is to create action • Evolutionary reason for development of perception • Motor activities • It can be a major action, like running toward the subject • It can be as subtle as blinking eyes • Response to perception and recognition • Leads to • New attended stimulus • Whole cycle repeats

26. Perceptual Process Perception Knowledge Recognition Processing Action Transduction Environment Stimulus Stimulus on Receptors Attended Stimulus

27. Knowledge • Affects • Processing, Perception, Recognition • Identification from memory • Old knowledge • Recent knowledge

28. Cognitive Influences on Perception

29. Cognitive Influences on Perception

30. Cognitive Influences on Perception

31. Cognitive Influences on Perception

32. Gestalt Psychology • Gestalt (German) • Essence or shape of an entity’s complete form • A theory of mind and brain • Gestalt psychologists stipulate that perception is the product of complex interactions among various stimuli • The whole is different than the sum of its parts • Contrary to the behaviorist approach to understanding the elements of cognitive processes • There are principles (or heuristics) often referred to as the “laws of perceptual organizations”

33. Images taken from http://psychology.about.com/

34. Images taken from http://psychology.about.com/

35. Images taken from http://psychology.about.com/