Perception Lecture 1

Perception Prof. Jonathan Winawer

[email protected]

Syllabus, lecture slides, study questions announcements, etc. available at NYUClasses

https://newclasses.nyu.edu

Course AssistantsZuzanna Kłyszejko [email protected] sections*2  T 3:30-4:45, 7E12 1293  T 9:30-10:45, WAVE 435

Serra [email protected] Recitation sections*3  W 3:30-4:45, BOBS LL1384  M 3:30-4:45, 25W4 C13

* Note on recitation organization

A few personal comments

Classics(BA, Columbia)

Myopia and eye growth

(MS, CCNY)

Cognition & Perception(PhD, MIT)

Seeing and the brain(Postdoc, Stanford;Assistant professor,

NYU)

Course acknowledgements: •  Brian Wandell (Stanford)•  David Heeger (NYU)•  Michael Landy (NYU)•  Marisa Carrasco (NYU)•  Larry Maloney (NYU)•  Kalanit Grill-Spector

(Stanford)

John Locke and Perception

Let us suppose the mind to be, as we say, a white paper void of all characters, without any ideas: - How comes it to be furnished? Whence comes it by that vast store which the busy and boundless fancy of man has painted on it with an almost endless variety?

Whence has it all the materials of reason and knowledge?

To this I answer, in one word. EXPERIENCE. In that all our knowledge is founded; and from that it ultimately derives itself (Locke, 1690).

The reason many of you have heard of the tabula rasa argument is because it underlies that phrase that is so familiar to Americans:

``we hold these truths to be self-evident, that all men people are created equal.''

John Locke and Perception

The main problem of perception:

How does the physical

world reach our consciousness?

Perception

•  Objectivist view–  Our senses precisely, and accurately, reflect the physical world.

They provide us with a true, complete, and accurate representation.

J.J. Gibson (Cornell)Direct Perception

Human Abilities•  Detect a candle, 30 miles away, on a dark, clear

night•  Detect the tick of a watch, in a silent room, at 20

feet - cochlear displacement equal to the width of a hydrogen atom

•  Taste one teaspoon of sugar even when it is mixed into two gallons of water

•  Smell a drop of perfume diffused into the space of a three bedroom apartment.

Galanter, 1962

Perception

•  Objectivist view–  Our senses precisely, and accurately, reflect the physical world.

They provide us with a true, complete, and accurate representation. •  Subjectivist view (Gestalt)

–  There is no inherent organization to the world, but rather, our brain organizes our perceptions, and we therefore believe the world is, itself, organized.

Kohler Wallach AmesWertheimer

See Ch 5 on Gestalt Psychology

Rotating Mask Illusion

Richard GregoryLink: http://www.richardgregory.org/experiments/

Apparent Motion

When you view one frame, and then the other, in alternation, you have the perception of motion through the intervening space. (Why might you interpret it this way?) The Gestalt psychologists took this as evidence that “the whole is greater than the sum of its parts,” since each frame by itself is static.

Apparent Motion

When you view one frame, and then the other, in alternation, you have the perception of motion through the intervening space. (Why might you interpret it this way?) The Gestalt psychologists took this as evidence that “the whole is greater than the sum of its parts,” since each frame by itself is static.

Ambiguous Apparent Motion

Ambiguous Apparent Motion with Grouping

Grouping Vase for the

Queen's Jubilee Gift

Illusory surfaces: Kanisza triangle

Peter Tse

Illusory volumes

Illusory curves

Interpretation The essence of Perception

Interpretation The essence of Perception

Visual System Interprets Images

Dakin and Bex, 2003, Proc. Roy Soc.

Anderson & Winawer, Journal of Vision, 2008Anderson & Winawer, Nature, 2005

Local image features are ambiguous

Interpretation depends on context


Local image features are ambiguous



How are visual features combined over space?


Fraser's Spiral

Gestalt interpretation: 'The whole is greater than the sum of its parts'

Size Constancy

E.G. Boring

Beuchet Chair

Size Constancy

Turning the tables

Roger Shepard

Memory can change what you see

Yoon, Witthoft, Winawer, Frank, Everett, Gibson, Markman, Cog Sci Proceedings, 2011





Gestalt Principles•  In this view, our perceptions may be likened to

the output of a piano: these perceptions are evoked by the world, much as the piano melody is evoked by the pianist.

•  A piano can only emit its own notes – it can't sound like a clarinet. Similarly perceptions are evoked by the world, but they generate experiences limited by the neural structures of our brain.

•  Our percepts are evoked by nature; but they are personal and not a copy of nature.

•  Objectivist view–  Our senses precisely, and accurately, reflect the physical

world. They provide us with a true, complete, and accurate representation.

•  Subjectivist view–  There is no inherent organization to the world, but rather, our

brain organizes our perceptions, and we therefore believe the world is, itself, organized.

•  Synthetic view The world appears to us the way it does because:(1) We perceive only within the limits of our nervous system(2) Our nervous system has evolved to reflect portions of the

world very accurately.

Perception: Our ApproachHelmholtz Shepard

Our Approach to Understanding

•  We are striving for a theory of perception in which every term, every idea, is well-defined. Much of what this course is about is trying to give you a sense of science generally, and what it means to say that we really understand something.

•  To test our understanding we often ask: –  Can we design a machine that perceives (Computer vision)–  Can we fix the perceptual system (Medicine, Engineering)

•  When we understand something well, there are usually important applications for that understanding.

Designing machines that perceive

Fixing perceptual systems: Hearing aids and Cochlear Implants

Neurological Interventions(Fine, Brewer, Wade, MacLeod, Wandell, Nature Neuroscience,

2002)

•  Chemical accident at 3 yrs •  One eye lost; other cornea destroyed •  Blind from age 3 through 46 •  Stem cell replacement in right eye for both epithelium and stem cells

Corneal epithelium

cells Limbal

epithelial stem cells

Syllabus Overview

•  Measuring perception–  Chapter 1, Appendix

•  Visual perception–  Chapters 2-10

•  Audition and speech–  Chapters 11-13

•  Touch–  Chapter 14

•  Smell and taste–  Chapter 15

Syllabus * See NYU Classes. It may change slightly.

DATE TOPIC READING RECITATION

2‐Sep Introduction Chap.17‐Sep NO CLASS (Labor Day)9‐Sep Psychophysics Chap.1 and Appendix

14‐Sep Signal detection Chap.1 and Appendix 1. Psychophysics & SDT

16‐Sep Optics and the eye Chap.2 (21‐26)21‐Sep Retina, transduction, light/dark adaptation Chap.2 (26‐ 35) 2. Optics & Retina

23‐Sep Electrical signals and Retinal ganglion cells Chap.2 (35‐44); Chap.3 (53‐62)

28‐Sep Receptive fields and sensory codes Chap.3 (62‐end) 3. Receptive fields

30‐Sep Cortical visual pathways and functional specialization 1 Chap.4 (77‐83)5‐Oct Cortical visual pathways and functional specialization 2 Chap.4 (83‐92) 4. Cortical pathways

7‐Oct REVIEW 1*13‐Oct EXAM 1 (*Tuesday with Monday schedule) CHAPTERS 1‐4, Appendix14‐Oct Recognition and perceptual organization Chap.519‐Oct NO CLASS Society For Neuroscience 5. Attention

21‐Oct Attention and visual awareness Chap.626‐Oct Motion Chap.8 6. Motion

28‐Oct Brightness Chap.9 (217‐220)2‐Nov Color Chap.9 7. Color & Brightness

4‐Nov Depth, size and shape Chap.109‐Nov REVIEW 2 8. Depth, Size, Shape

11‐Nov EXAM 2 CHAPTERS 5‐6, 8‐1016‐Nov Sound and the ear Chap.11 9. Sound, Pitch, Loudness

18‐Nov Pitch23‐Nov Loudness25‐Nov NO CLASS‐THANKSGIVING30‐Nov Auditory pathways and localization Chap.12 10. Localization and Speech

2‐Dec Speech perception Chap.137‐Dec Touch Chap.14 11. Touch, Taste, Smell

9‐Dec Smell & Taste Chap.1514‐Dec REVIEW 321‐Dec EXAM 3, 2 pm – 3:15 (see NYU final exam schedule) CHAPTERS 11‐15

Web page: NYUClasses

https://newclasses.nyu.edu

Please check the web page regularly– Syllabus & schedule– Announcements – Practice exams– Study questions

Text Book & ReadingsSensation and Perception (9th edition)Goldstein (Wadsworth)

-  Hard copy (bookstore)-  Ebook (bookstore or online)-  Rental (online)

Recitation sections•  Recitation sections meet once per week (most

weeks – see syllabus)•  You must register for one!•  Bring clickers! •  Topics are on the syllabus•  Study questions are due Mondays at noon

during weeks with recitations•  Complete on NYU Classes•  Study questions will be posted no later than

Wednesdays (for the following Monday)

Exams•  Exam 1 (10/13/2015) (Tuesday with Monday schedule!)

–  Up to and including cortical visual pathways–  Chapters 1-4, appendix, and online lecture notes

•  Exam 2 (11/11/2015)–  Recognition through depth, shape, size–  Chapters 5-6, 8-10

•  Exam 3 (12/21/2015)**–  Hearing through chemical senses–  Chapters 11-15

** Exam 3 is scheduled during the final exam time period, but it is NOT a final exam. All three exams are weighted equally and no exam is cumulative.

•  Review sessions before each exam (see syllabus)•  Exams will include material in book not covered in lectures and material

from lecture not covered in book

End

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Perception Lecture 1