CS 182 Sections 103 - 104AnnouncementsQuick RecapQuiz!Slide 5A Tour of the Visual SystemRods and Cones in the RetinaThe Microscopic ViewWhat Rods and Cones DetectCenter / SurroundHow They FireColor Opponent CellsSlide 13The WCS Color ChipsResults of Kay’s Color StudySlide 16Categories & Prototypes: OverviewBasic-Level CategorySlide 19Category StructurePrototypeMotherRadial Structure of MotherMarriageLanguage and ThoughtCS 182Sections 103 - 104slides created Eva Mok ([email protected])Feb 22, 2006(http://www.ritsumei.ac.jp/~akitaoka/color-e.htmlAnnouncements•a3 part 2 due tonight, Feb. 22nd, 11:59pm•my office hours have moved to 2 Evans•I have some of yr quizzesQuick Recap•Last Week–Finished up backprop and neural networks–Color: neurophysiology, psychophysics, etc.•This Week–Imaging techniques (fMRI, etc.) –Categories & concepts•Coming up–Image Schemas, Force-DynamicsQuiz!1. How do humans detect color biologically?2. Are color names arbitrary? What are the findings surrounding this?3. What constitutes a basic-level category? Is red a basic-level category? Is maroon?4. Why does it take longer to determine whether “100 is close to 99” than “99 is close to 100”?Quiz!1. How do humans detect color biologically?2. Are color names arbitrary? What are the findings surrounding this?3. What constitutes a basic-level category? Is red a basic-level category? Is maroon?4. Why does it take longer to determine whether “100 is close to 99” than “99 is close to 100”?A Tour of the Visual System•two regions of interest:–retina–LGNhttp://www.iit.edu/~npr/DrJennifer/visual/retina.htmlRods and Cones in the RetinaThe Microscopic ViewWhat Rods and Cones DetectNotice how they aren’t distributed evenly, and the rod is more sensitive to shorter wavelengthsCenter / Surround•Strong activation in center, inhibition on surround•The effect you get using these center / surround cells is enhanced edgestop: the stimuli itselfmiddle: brightness of the stimulibottom: response of the retina•You’ll see this idea get used in Regier’s modelhttp://www-psych.stanford.edu/~lera/psych115s/notes/lecture3/figures1.htmlHow They Fire•No stimuli: –both fire at base rate•Stimuli in center: –ON-center-OFF-surround fires rapidly–OFF-center-ON-surround doesn’t fire•Stimuli in surround: –OFF-center-ON-surround fires rapidly–ON-center-OFF-surround doesn’t fire•Stimuli in both regions:–both fire slowlyColor Opponent Cells•These cells are found in the LGN•Four color channels: Red, Green, Blue, Yellow•R/G , B/Y pairs•much like center/surround cells•We can use these to determine the visual system’s fundamental hue responsesMean Spikes / SecWavelength (mμ)25400 700+R-G5025400 700+G-R5025400 700+Y-B25400 700+B-Y(Monkey brain)Quiz!1. How do humans detect color biologically?2. Are color names arbitrary? What are the findings surrounding this?3. What constitutes a basic-level category? Is red a basic-level category? Is maroon?4. Why does it take longer to determine whether “100 is close to 99” than “99 is close to 100”?The WCS Color Chips•Basic color terms:–Single word (not blue-green)–Frequently used (not mauve)–Refers primarily to colors (not lime)–Applies to any object (not blonde)FYI:English has 11 basic color termsResults of Kay’s Color StudyIf you group languages into the number of basic color terms they have, as the number of color terms increases, additional terms specify focal colorsStage I II IIIa / IIIb IV V VI VIIW or R or Y W W W W W WBk or G or Bu R or Y R or Y R R R RBk or G or Bu G or Bu Y Y Y YBk G or Bu G G GBk Bu Bu BuW Bk Bk BkR Y+Bk (Brown) Y+Bk (Brown)Y R+W (Pink)Bk or G or Bu R + Bu (Purple)R+Y (Orange)B+W (Grey)Quiz!1. How do humans detect color biologically?2. Are color names arbitrary? What are the findings surrounding this?3. What constitutes a basic-level category? Is red a basic-level category? Is maroon?4. Why does it take longer to determine whether “100 is close to 99” than “99 is close to 100”?Categories & Prototypes: Overview•Three ways of examining the categories we form:–relations between categories (e.g. basic-level category)–internal category structure (e.g. radial category)–instances of category members (e.g. prototypes)FurnitureSofa DeskleathersofafabricsofaL-shapeddeskReceptiondiskBasic-Level CategorySuperordinateSubordinateBasic-Level Category•Perception: –similar overall perceived shape–single mental image–(gestalt perception)–fast identification•Function: –general motor program•Communication: –shortest–most commonly used–contextually neutral–first to be learned by children–first to enter the lexicon•Knowledge Organization:–most attributes of category members stored at this levelWhat constitutes a basic-level category?Red? Maroon? yes arguable (expertise)Quiz!1. How do humans detect color biologically?2. Are color names arbitrary? What are the findings surrounding this?3. What constitute a basic-level category? Is red a basic-level category? Is maroon?4. Why does it take longer to determine whether “100 is close to 99” than “99 is close to 100”?Category Structure•Classical Category:–necessary and sufficient conditions•Radial Category: –a central member branching out to less-central and non-central cases–degrees of membership, with extendable boundary•Family Resemblance: –every family member looks like some other family member(s)–there is no one property common across all members (e.g. polysemy)•Prototype-Based Category•Essentially-Contested Category (Gallie, 1956) (e.g. democracy)•Ad-hoc Category (e.g. things you can fit inside a shopping bag)Prototype•Cognitive reference point–standards of comparison•Social stereotypes–snap judgments–defines cultural expectations–challengeable•Typical case prototypes–default expectation–often used unconsciously in reasoning•Ideal case / Nightmare case–e.g. ideal vacation–can be abstract–may be neither typical nor stereotypical•Paragons / Anti-paragons–an individual member that exhibits the ideal•Salient examples–e.g. 9/11 – terrorism act•Generators–central member + rules–e.g. natural number = single-digit numbers + arithmeticMother•The birth modelThe person who gives birth is the mother•The genetic modelThe female who contributes the genetic material is the mother•The nurturance