PSYCHOLOGY OF PERCEPTION
PSYCHOLOGY OF PERCEPTION PSYC 351
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This 225 page Class Notes was uploaded by Morris Rolfson on Monday October 19, 2015. The Class Notes belongs to PSYC 351 at Rice University taught by James Pomerantz in Fall. Since its upload, it has received 88 views. For similar materials see /class/224983/psyc-351-rice-university in Psychlogy at Rice University.
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Date Created: 10/19/15
Psychology 351 Pomerantz Psychology of Perception Week 2 Philosophical Issues in Perception Basic Facts about Perception Three key questions Mindbody relationship origins of knowledge what is to be explained Mind body problem Is mind matter Does mind matter Monism mind and body are one Materialism idealism radical skepticism Dualism mind and body are two separate entities lnteractionism epiphenomenalism Free will vs determinism Reductionism and emergent phenomena Functionalism hardware software body mind Epistemology origins of knowledge The Oracle the environment genes nowhere Realism critical vs naive What must be explained Behavior phenomenology underlying processes Converging operations Mental representation Psychophysical isomorphism complementarity Ten facts about perception Perception 1 Is limited We detect only a slim portion of the information and energy around us Frequency Spectrum Infrared Scene Mite Powers of Ten Edgerton Bullet Galloping Horse J U A U 0 l 00 O Is selective Of that information we do detect we can attend to only a small fraction at any one moment cocktail party phenomenon Requires memory Advanced perceptual systems store perceptual memories and then match in owing sensory information against those memories to allow recognition and prediction Is not entirely veridical trustworthy We experience illusions that reveal how normal faithful perception works Hermann Grid Spiral Illusion Simultaneous Contrast moon illusions optical illusions most illusions aren t optical in origin for more see Illusionworks and the PBS site wwwpbsorgwnetbrainillusionsindexhtml Takes time We do not perceive the world in real time but at a slight delay as neural processing unfolds icker Metacontrast slowed down Corresponds more to the distal than to the proximal stimulus We perceive the invariant properties of the world around us not the eeting and accidental properties resulting from viewpoint illumination etc Shepard Boxtops Adelson Shadow Effect Involves the active organization of sensory information We don t receive information passively but piece it together into a model Hexagram of Spots R C James Photograph Focuses on change not on steadystate information disappearance of stabilized images adaptation McCollough Effect Adaptation to steady state is the norm in perceiving both external stimuli eg brightness loudness and internal emotional states like happiness Involves both bottomup andtop down processing Bottom up focuses on sensory information owing from receptors to the brain39 top down focuses on hypotheses and predictions generated in the brain and on feedback from the brain back down to the receptors Mismatches between bottomup and topdown ie between what we expect to perceive and what we actually perceive attract our attention 10Is based on our brain s model of the world an internal representation of distal reality It is this model that we perceive not the world itself with missing bits of sensory information filled in Necker Cube Subiective Necker Cube Attention is drawn to mismatches between our model and incoming stimulation 351Week2d0c June 2006 Psyc 351 Depth and Space Perception Functional Utility of Depth Perception Locaization of objects surfaces in 3D figureground edge detection grouping The Problem in Depth Perception Lens 9 Light doesn t tell us how far it s travelled Our retinas are effectively 2D flat Two solutions to this problem a Direct b Indirect Depth infai r ation y w1 Alt 39I ax 713 Perspective 5 u L F IE U RE 3 Major snurccs of depth infm nmli n Direct Solutions to Depth Oculomotor Kinesthetic and Gibsonean Oculomotor accommodation no and convergence yes Gibsonean texture gradients optical flow invariants Ocularmotor Cues Accommodation amp Convergence Accommodation the convexity of the lens Convergence the angle at which the two eyes point Accommodation amp Convergence A Accommodation swam 1uge lo musc es 1 Convergence slram gauge Extraocu av musc cs Motor comm camera in brain FIGURE 88 Twu pnwihlc hcmn 1m rcgmrriug urulummur inlku39nmlmn Indirect Solutions Use Visual Depth Cues Unconscious inference Binocular cues retinal disparity and stereopsis Monocular cues lots of them Binocular Cues Overview Disparity crossed and uncrossed horopter Wheatstone stereoscope Panum39s area Julesz random dot stereograms Correspondence problem false matches Computation of disparity Binocular Cues continued Head motion lr reversal LTM tool for localization Pulfrich effect Binocular rivalry suppression Disparitysensitive cortical cells Stereoblindness strabismus amblyopia Note lack of awareness of eye of entry Strabismus Walleyes strabigmusj Binocular Disparity Binocular Disparity ABDC ADBC Disparity and the Horopter Uncrossed disparities Fixai ion point Horopter zero disparity disparities Left eye Higm eye Disparity and the Horopter a Crussed disparity h Uncrussed disparity gmm Em Stereoscopic Vision Stereoscope Sir Charles Wheatstone 1838 mwm mmgt Bela Julesz Randomdot stereograms Bela Julesz Randomdot Stereograms FIGURE 5 13 Magic Eye in n a v a 14 h in v I a 4 False Fusions amp the Correspondence Problem Binocular Rivalry 13ft eye right Eye Binocular Rivalry Monocular Cues to Depth Interposition static or dynamic occlusion Size assumed or familiar ball and faces Ames Moon Monocular Cues to Depth Interposition static or dynamic occlusion Size assumed or familiar ball and faces Ames Moon Sizedistance coupling Emmert39s law Size constancy and illusions of depth Gregory39s explanation of Muller Lyer Monocular Cues to Depth Linear perspective Alberti39s window texture gradients arial perspective Height in the image esp height of bottom Motion parallax relative movement Shading and shadows bumps and dents Pictorial monocular Depth Cues Pictorial Cues continued Depth from Shading Depth from Texture Gradients FIGURE 5225 corner Depth amp the Moon Illusion Mnon at zenim Pictorial Depth Cues More Pictorial Depth Cues Shading Occlusion contours Texture gradients dots and parallel lines TRENDS in Cognitive Sciences Figure 1 Some possible sources of visual information for the depiction of 3D shape The BD shapes in the four different panels are perceptually specified by a a pattern of image shading b a pattern of lines that mark an object s occlusion contours and edges with high curvature c gradients of optical texture from a pat tern of random polka dots and d gradients of texture from a pattern of parallel surface contoursi Lichtenstein House Washington DC Depth Cues in Photography DoF Monocular Cues to Depth 0 Holway and Boring experiment cue reduction breakdown in constancy Pitting cues against one another incongruity Depth 3D Structure from Motion Kinetic Depth Effect 0 KDE at equiluminance Hollow Faces Gregory httpwwwmichaelbachdeotfcs hollowfaceindexhtml Grand Illusion website The three draqons Also Bent card illusion Mach Luminance Looming httpwwwmichaelbachdeotsze lumiloomindexhtm Trompe I39OEiI art pronounced quottromp on 0 Julian Beever site Ei Visual Cliff Eleanor Gibson Functional Utility of Sound Carries information helpful for locating where things are where you are outside in a large room on firm ground etc 0 Carries information good for identification we can identify friends from their footfalls Travels well in air not that quickly and with echoes and reflections but overall does well The nature of sound Pressure waves compression and rarefaction Sine waves Three dimensions of sound Ampitude Frequency Phase Speed of sound 1100 feetsec in air x 5 faster in water Amplitude Frequency Phase Guim string exaggerated Pressure waves Sine waves Three dimensions Amplitude Frequency Phase Alrmoiecuizs 0 0 0 0 0000000000000 00000000000 0000 Di won or sauna gt 000000 0 0 0 o 0 0000000000000 0 0 0 0 0 0 0000000 Ccmprassmn Raralsnion 0 0 000 00000000 0 0 0 0 0000000000000 0 0 0 0 Wzveieng quot m Amplitude wequot aquot I i phase angiei Haralamon Diagram nf sauna wave a time A Wavrlength 13Ltrequnq 31 guzL 00 Wmlmgm 12 frequcncy Sounds in the natural environment Glass breaking Brushing teeth Distant thunder FIGURE 111 Each soundwave wave corresponds to a unique acoustic event Fourier analysis Fourier Analysis analyzing complex waves into simpler components sine waves Fourier Synthesis the reverse adding sine waves to create complex waves Fourier analysis 26 cymas degree we wave 26 cyclesdeg39ee squa39e wave Founev analyze Fourler analyze mm W FundamemaL 26 cyclesdeg 3rd harmomc 78 cyclesdegree 5m hammmc 130 cyclesdegree Fourier Synthesis quot Representations amplitude waveforms vs spectrographs Waveform Spectrum 1 0 ll tone 1 0 1 wave 1 0 2 I Train of pulses o 0 Amplitude g LLLLl 3 a 2 Single 5 1 pulses G 6 1 We l house 1 0 1 Short 0 tone 1 0 l O l 2 3 0 I 500 10000 Time in milliseconds Frequency in Hertz figure 121 On the left are shown the waveforms of some common auditory stimuli and on the right are the corresponding spectra The periodic stimuli pure tone square wave and train of pulses have line spectra while the nonperiodic stimuli single pulse white noise and short tone burst have continuous spectra Amplitude The Decibel scale A ratio scale referenced to the classical threshold of human hearing nominally 0002 dynescm2 Factoid dyne force needed to accelerate lg to 1cmsec in 1 sec A logarithmic scale converts multiplicative changes to additive changes Thus db 20 x log PlPO in sound pressure level where PO 0002 dynescm2 Amplitude Range Business of ce Heavy truck Iackhammer Jet take0ftquot 1 A T quotE 7 Threshold Threshold ofhearingl 1 0 20 30 40 SD 60 7D 80 9f 10039110 120130 140 otpain Loudness dB numu new 54 39 I Frequency cyclessec or Hertz Hz from German physicist Heinrich Hertz Middle C on piano N 2616 Hz MW wikipediaorgwikiPianofrequencieg m was 1 um um m um 53 3 Frequency Frequency Range for Human Hearing Nominally 20 20KHz fuilaudrmsscmmmus rm dam of Robin 1 and Dadson IS39SSL Sound Incl dB 59 of lanes 111 match 1 stmlnrd ton in 1011de 03990 I39I39l39qllral c I 1 In mun F Sound Intensin dBSPL Normal vs Impaired Hearing 391 20 100 EU 8D 40 2C 0 Normal I lmip 39ifed 39 39 I l I l IJW EU l r I MI 100 500 LDDEI Frequency Hz VI I l lV JI7 50 100 Comparative Hearing 80 Dolphin Elephant I Dolphin Mouse l Dog 39I 60 397 Do I g l I I A 39 l g 39 l I 40 Elephant I I Z I l 2 I I a 20 Il I E I l I I 0 I Mouse a 20 I I l l 100 1000 10000 100000 200000 Frequency Hz Phase The relative positionstiming of two waves matched for db Hz 120 D egreee Three Phase Generation Sine 39W39auex Phase Three binaural cues to the direction from which a sound is coming Phase difference between left and right ear I II I I6 Of arrival difference olntensity different head creates an auditory shadow Monaurally humans appear to be phasedeaf Sou nd source quoti i Ex U l t The Ear versus the Eye Orientation Attention bpeeo Sensitivity Echoes Eye 400 700 nm trichromaticity Ear 2020k Hz quotTri tonaticity No Structure of the ear Outer structures pinna Inner structures Auditory canal Tympanic membrane acoustic reflex Ossicles Malleus Incus Stapes Oval window Cochlea basilar membrane Organ of Corti Cilia inner vs outer hair cells Mechanism of transduction Impedance matching 30 db loss The Ear starting from the outside The Ear in cross section semicircular canal Stirrup Auditory nerve Anvil Bony cochlea Inner ear Auditory or Eustachian tube r 7 3939Eardruni I Extcr nalauditory cranal 39 0 mar ear The Ear in crosssection Malleus Stapes Semi Oval Incas Circular wmclaw Vestibular nerve Concha Ccchlear nerve Raund 39 d Ear canal wm GW Eustachian tube Pinna membranE WWW FluIli t l39l GermIhmw Semicircular canal Stirrup Auditory nerve Bony cochlea Inner ear Auditory or Eustachian tube Eardruhjl Middle ear gt Canal 2 Outer ear Middle Ear lnnurear sump 51mm Ear canal dchmn hbe FIGURE 99 The middle ear Malleus Imus Tensor Stapes x f Tympanic Stapedius Raund Base of membrane muscle window stapes in OWN Mndow sumWWW ME IMM 33 am 5 m Ill Auditory Vestibular nerve Auditory RENE Round window Enables mmm Hul39dlt39l39l emmmm Dynamics of the middle ear httpfunsanbiomedmcgilcaquot funnelOpenHouse96meanimhtm Ve slibula i39 banal Cochlear duct Tympanwe m Round window FIGURE 1012 A sculinn nl un unvudcd cochlea Cross SEEHDII of mhlea Remner s membrane Tect rial A membrane r r Middle quot canal hair cells Basillar membrane mmm til lan Gammamm Tecturiall membrane Stereocilia 39rr 1 Outer f quot Basilar 39 39 Tunnel EEETE t hair cells x membme Manet of Corti be Af erent bers hair cells mnmnmm nl m BWWWE BasHar Membrane Oval window T Direction of traveling wave gt f W Time 3 4 5 Base Apex Base Apex Response 0 highfrequency tone Response to lowfrequency tone FIGURE 1020 The top drawing shows a traveling wave deforming the basilar membrane The set of curves below at the left represents the response of the busilar membrane overtime to a highfrequency tone The curves at the right represent the basilnr membrane39s response over time to a lowfrequency tone 5 1Hf Hair Cells outer and inner kAA u u 1 1 I hm Mouse Organ of Corti courtesy of Audrey Nath and Jeff Triffo M Brain Pathways for audition Cochlear nucleus Superior Olive Mw gomculalc Inferior colllculus nudws Medial geniculate Auditory Cortex A1 mum willwlus Audllorycorlex Cochlear nucleus Lell audllmy nerve Righl audllmy nerve dB SFL Auditory Tuning Curves 0 1 1 o 1 00 Frequency kHz More Auditory Tuning Curves Mimmum sound mtensily dam needed to ehcit neural response I 100 300 500 1000 30070 5000 10000 Tone irequencv 1H2 Tonotopic Map of Monkey Auditory Cortex Figure 1045 The outline of the core area of the monkey nudith cortex shinning the tonotnpie map on the primnn39 auditory reeeiting area At which is located within the core The nnmhers represent the characteristic frequencies CtquotJ n nenznns in thousands tiHZ Notice that It39s range from 250 H on the hit to 20000 H on the tight Adapted from Kosahi et at WW Inner Ear Summary canals lntus stapes wmdow Bone a Semitivcular d va 1 25 Hz 50M Round Cothlea Auditury window nerve Relative envelope amplitude Sula vestibuli Ioo Hz v Perilymph 200 Hz fibers Scala tympani Perilymph lntraganglionic SDi B39 bundle Tunnel at cm Basilar 00 HZ neurons Rods of Com membrane 800 Hz Basilar membrane displacement I I l 20 21 22 23 25 26 27 28 29 3O 0 I0 20 30 Distante from stapes mm Distance from stapes mm I I I I I I I Hillquot 111 Panel a illusrrates the structure of the peripheral auditory system showing the outer middle and inner ear Panel b shows a cross section of the cochlea Panel c shows schematically the waveform on the BM at four successive instants in time in response to a lowfrequency sinusoid The pattern moves from left to right building up gradually with disrance and decaying rapidly beyond the point of maximal displacement The dashed line represents the envelope traced out by Coding mechanisms Place theory coding frequency and amplitude Volley principle large numbers of detectors Periodicity coding frequency and amplitude Duplicity theory 1 KHz to 4 KHz Missing fundamental masking Pathways and Brain Mechanisms Cochlear nucleus Superior olive Inferior colliculus IVIedlal genlculate Auditory cortex Tonotopic mapping Tuning curves for quottone detectorsquot Detectors tone onsetoffset sweep Psychophysics Basic audiogram repeat from earlier in semester 0 Masking critical band Overview of Perceptual Organization Principles Methods Findings amp Theory Based on a series of lectures given At BISCA 2001 Bolzano Italy James R Pomerantz Department of Psychology Rice University Houston Texas USA 2 RICE Perceptual Organization in the 1 93 Os Karl Dallenbach s photograph Perceptual Organization in the 19703 R C James s Photograph 3 Perceptual Organization in the 20003 BeV Doolittle s Painting Key Issues Raised by Dallenbach s Cow Where are the objects in the image Where does one object stop and the next one start Which edges represent illumination changes and which re ectance changes What are the objects What is the role of knowledge topdown processing in segmentation and identi cation Road Map for Lecture What is Perceptual Organization as I approach it Why do I think this problem is important Phenomena Methods and Findings Theories Speci c and General Remaining Questions Future Directions What Is Perceptual Organization the processes by which the bits and pieces of visual information that are available in the retinal image are structured into the larger units of perceived objects and their interrelations Stephen E Palmer Vision Science 1999 What Is Perceptual Organization Perceptual Organization is central to the key question of perception how do we make the leap from information detected by our sensory receptors to our perceptions of the world This requires not just the detection of information by the organization of that information into veria ical percepts Pomerantz amp Kubovy 1986 2 RICE What Is Perceptual Organization Perceptual organization is the process by which particular relationships among potentially separate elements including parts features and dimensions are perceived selected from alternative relationships and guide the interpretation of those elements in sum how we process sensory information in context Pomerantz amp Kubovy 1986 Why Study Perceptual Organization It is arguably among the earliest steps in perceptlon It is an essential tep solving basic questions that must be resolved before further image analysis takes place Note The Problem of PO Extends Beyond Images of Animals There Are Many Many Others I In I Q HtLENIIlll 39q Fa Wqu 15mm at hor mm Hm won am rmv intH M1 a um 15 mag a ham 01 quotJun ti jiLx an an 01 Evrm PIqu Iiiquot UU BUD I lii i QQDGUGDD I GGEQEGQGDD iiIIIIIIQII Ili39llilll QUOGUGDDDG GBGDGGDQGD glaill More Classic Examples of Perceptual Organization NO GROUPING 00000000 GESTALT LAWS OF GHDUPING OO 00 00 OO PROXIMITY OOOOOOOO SIMILAle JEJEJEJ CLOSURE GOOD CONTINUATION NEWLY PROPOSED LAWS 00000000 COMMON REGION HHHo o CONNECTEDNESS j 45 sw w thlll l mm 395 DRUNK f4 f5 7 393 Fig 14 What is this 3 H3 gt RICE Illlllllllllllllll lllllllllllll I l llli 39 39 45 u I kuu um Jung quot1 Hm I Cavrrr39r 2 T i1 WI l l I 7 l I 39 l 39 l I I q u LL l 1 4 l l xquot z 3 1 I l l LA 1 I l y r E z i g u a agx More Classic Examples of Perceptual Organization More Classic Examples of Perceptual Organization 544 FDMEHANT AND RUBENquot I lli L39l39tli HJ Hochbergs Hacker Cube FIE 133 31111 imp39IeMH HIM ick clu39is created Sienna31 mm lm Th shammoi Itc3931ick clams am A 5mm serum 3 Ila lhrttvuiu k ikwn i Eiuull while clul i n light hllilclml In menu MM I39 ul L1 person39s may tDravEnss uti p ri from Julmn mrn IQ39FS mmmmmmmmmwmmmmmm fimmlmmmmmmmmmmmmmm Figure gr39eund segmentation pmhlem 39 quot HMl MhI JJINI N lh I HCIR l H 39 Inuit11m I39ll39h Ik n l d mmmimlmmmmmmmmc mmm Ln mm m m in mm U1 U1 milLn U m m UT mmmlmmmmmmm 1111 A rug Imam us 2 w my rawIprz 4leanquot r blah try an mall r5519 li quotL rizrmlndifwmlru an n Falluw 1hr mmmfmggmmmmmmmmmm mmmlmmmmmmmmmmmmm mmm39mmmmmmwmm mmmm mmmmmmmmmmmmmmmm mmmmmm mmmmm mmmm m mmmmm mmmmmmmmmmi m mmmm mmmmmm39mmmm im unmeasurmmmmmmmmmm mm mmmmlmmmmmmmL mim39mm mmmi mmm jmmmmmrgmimmmmfmmmmm gl More Classic Examples of Perceptual Organization More Classic Examples of Perceptual Organizati in Fm MumF ii39wqi vi 39 I 139 I 39 1115 u39I 7 quot 4 Pi 1 r 39 I w l 2 2 r Eiht UJ 5 l Iquot Thai In Ear lt NHLnun uI 7Jlkl39l i m w quotill I Flgtifl 52414 39J1F whim lmmw nn mil mIZr ll u 53939mm rrtjal black mlumna 1 17 More Classic Examples of Perceptual Organization E E Component Issues in Perceptual Organization Grouping and segmentation Dalmatian Laws of Grouping Part Whole relations Figure ground segregation Rubin s Vase Doolittle s ponies Emergent Features Subjective Contours Configural Superiority Effects Perceptual coupling constancies Shepard s Boxtops Ames Room Multi stability Necker cube Barber Pole Globality Simplicity Grouping and Segmentation ooooo Ow 39 ODDOIO39O 00DiUIO39OI 000000IQ O Q o D o O I O I O 39 00OCDIO39Q39 DID39D39O39D39O39 QQQrQGOIO39Q39 From Wertheimer 1923 llllt I 20 RICE 5 39 39 l av n 4 q E Lower illustration 5 5395 1 1 I I F IEI e from K0f lta Eli I 23 i no GROUPING 00000000 GESTALT LAWS OF GHUUPING 00ltx30m00 PHDXIMIT Y SIMILAle 00000000 EJEJEJEJ CLOSURE 3C GG PD CONTINUATION NEWLY P39BDPUSED LAWS 00000000 COMMON REGION CONNECTEDNESS Grouping of Separated Elements g I 25 RICE Grouping of Separated Elements Figure Ground Segregation From Rubin RainErik mm created for gnaw EHer I39Jurb39s Elmer jubilee in 19752 We see either 1 mm or two pro les dqmm r39ng nu how we nrgmizzrrbr visual macaw Rubin quots Fiure Brought to Life Fig 14 What is Ibis 1 29 Kg RICE From Kanizsa r vgule 5294 The whhe Columns pram ovnrthe svmmen ica Mack mnnnm 130 RICE H 39 m1nummmmummml a I39111 3939I13939I1 j I H 3911 1H 3911 e39quot i ii39 5 f rt 3 1 i335 quot From Escher 1 1 31 9 RICE From Bregman 3 2 133 RICE THE LOGIC 0F PERCEPTION Irvin Huck From Rock Emergent Features the focus of my 211d and 3rd lectures From Wertheimer 1912 Phi or beta apparent motion plus the Correspondence problem from Grouping F4 r r DRGANIZATIDH EN VISION Figure 42 Net three black secrers and three anglea bur a white triangle in front at three black disks and an Duh lined triangie From Kanizsa 136 e RICE PERCEPJ UALORGANIZATION 295 Component Component Whole Emergent A B gure pro e Closure Horizontal surface Volume From CorenWard and m Enns Sensation amp Perception O Q 3 V L Y A u A mg 1 39 that cannot be tvplnined by examining the Component parts based on Enns 1990b Pomcmm 1986 Ramnchandmn 936 DISCREIMHNAWON DHR ECTIOM OF CURVATURE i gt gt H m Z j i I n E 1 F a a 39 quot a w I 2400 f 7 gt 739 295G Con gural Superiority Effects l llH 2 UHUANIXA l J IN VIEUN FigulE 1111 A leadg vinle Luntour w39thour gradients withDL difference5 in bright ness due ID contrasl I r V 39rt 1 139 d d EN 1 39 KER R17 E Perceptual Coupling From Shepard 1981 Two two yellow parallelograms have identical shapes Transparency 27 e Ames Room A 4 mm a mu m mm em m 1 739 K The Ames Room Note Kubovy and others don t always regard coupling as a Gestalt problem Multistability Fron1TJeckeL Kopferman all h From Temus Phenomenal Identity or the Matching Unit problem More Ternus Short ISI 0 msec Long 181 200 msec From Boring I 45 RIC From Wallaoh Wallaoh s overlooked variation polka dots 1 146 235 RICE Globality Configural effects work over large expanses of the Visual field not just local patches Eg color We achieve color constancies by comparing wavelength distributions across the entire Visual field E g the aperture problem in motion Simplicity amp Pragnanz the minimum principle At the heart of the Gestalt approach Claim We organize our percepts in the simplest way that is consistent with the information in the stimulus Cf distribution of electromagnetic fields Soap Bubble Metaphor The soap bubble computes an answer to a complex problem nding the simplest solution possible Question Does the human perceptual system work in a similar fashion PO and the Gestalt Psychologists Max Wertheimer Kurt Kof lta Wolfgang Kohler They identified the basic problem in some respects in its current terms and uncovered many of its phenomena They attempted a theory as well but it has has less impact The Key to Gestalt Effects NonAdditivity Stimulus A activates Representation A Stimulus B activates Representation B Q Will Stimuli A B activate Representations A B Something additional beyond this Something less than this Something simply different from this NonAdditivities in Perception Widely Heralded Slogan of Gestalt Psychology The whole is greater than the sum of its parts No No not the sum Summing is a meaningless procedure Kof lta 1935 NonAdditivities in Perception Rather The whole is different from the sum of its parts Sometime greater than sometimes less than often different from Better to say the Gestalt claim was that elements interact nonlinearly in perception Examples of NonAdditivities A11 involve the emergence of new features Color Apparent Motion Orientation Subjective Contours rientation Glass Patterns Oientation Glass Patterns Orientation Glass Patterns 157 RICE Apparent Motion Duncker s Rolling Wheel Fig 9 In pitch darkness 2 wheel with lights on the rim a or the hub b rolls slowly along a table When both lights are on the perception is not the simple sum of the perception of each light alone a I does no equal c The cycloid motion is lost and one light seems to rotate around the other a in From D Krech and R S Crutch eld Elemenm of Psychology New York Knopf 1958 Kanizsa s Subjective Contours F4 f ORGANIZATION EN VISION Figure 42 Not three black SECTOI S and three angles but a white triangle in front 0f three black disks and an out lined triangie s K RICE 160 Combine Subjective Contours With Apparent Motion 39 Reversed direction of apparent I motion in the bottom panel compared with the top indicates f nonadditivitity and suggests the dominance of subjective J contours in deciding what is moving O 1 0 61 a J J Bottom panel from Ramachandran Gestalt Psychology in 2001 Perceptual organization has languished in relative obscurity since the end of the Gestalt era In the latter half of the 1900s Vision scientists have generally ignored organizational issues as though such things as grouping partwhole relations reference frames did not really matter secure in their belief that linear systems analysis and single cell recording studies of cortical area V1 would lay bare the mysteries of perception The next frontier of Vision science will be to solve the problems of perceptual organization and its effects on Visual processing Stephen Palmer in press On the Other Hand Some of the researchers publishing on PO since 1950 Hochberg Rock Kanizsa Treisman Attneave Garner Spelke Palmer Kubovy Gerbino Shepard Biederman Metzger Leeuwenberg Metelli Graham Julesz Kahneman Miller Neisser Shepard Wolfe Reads like a Who s Who in Psychology Why is PO Such a Hard Problem Perceptual organization is dif cult to study because it lies on the border between our experience of the world and unconscious perceptual processing Even the term perceptual organization is ambiguous it means both the outcome of perceptual processes how things look and the mechanism that produces it the psychophysical processes that precede awareness Perceptual organization is dif cult to study for a second reason because it Involves both bottomup and topdown processes It is like respiration a semivoluntary process Michael Kubovy in press Grappling with Basic Concepts Example What is an object object is not an easy term to define Indeed textbooks with chapters on object perception generally just assume that we all know what is being talked about Jeremy Wolfe Barriers to Understanding Perception The problem of subjective experience Complexity of the stimulus confounds Transparency of perception The main barrier may be our own perceptual system 240 238 255 246 The Proximal Stimulus What object does this gure depict How many objects are shown Where are the object boundaries A Simpler Example 168 RICE The Answer Revealed 169 RICE Organizing a Stimulus Is Work 0 Looking at the last figure it seems obvious that there are figures there and clear how many there are and in what arrangement None of this is given for free however it must be computed by the visual system 0 The belief that the organization is in the stimulus and not computed is a fundamental error one of two the experience error and the stimulus error Paradox of PO Everybody knows what it is yet nobody seems to know what it is Its effects are robust and seemingly obvious Yet dif cult to measure Palmer KuboVy Complicating matters two errors we make 171 x a R Q 1 CE The Stimulus and Experience Errors In psychology we have often been warned against the stimulus error ie against the danger of confusing our knowledge of the physical conditions of sensory experience with this experience as such As I see it another mistake which I propose to call the experience error is just as unfortunate This error occurs when certain characteristics of sensory experience are inadvertently attributed to the mosaic of stimuli Kohler 192947 p 95 The Stimulus Error A presumption of what the stimulus is We know that a physical object is built out of certain parts so when we describe our perception we use those same parts Or we enter a room lit with one candle illuminate a second candle and report that the room is now twice as bright Striking counterexample the Gelb Effect where knowledge has little effect on perception The Experience Error A presumption that our perception is governed by the stimulus array We experience a percept that is organized eg is segmented into regions objects and parts So we assume that this organization is available in the proximal retinal image rather than having to be computed on the image by our visual system An Example of These Errors This stimulus is described as a box with a line drawn across it both containing a gap Do we see it that way If so is it because we constructed it that way And are these the real physical parts From Duncan 1984 An Example of These Errors Recall that this is a better description of the proximal stimulus Are the parts directly represented here Does this array support the notion of a box and a line With gaps Another Example IA Withingroup 896 ms l0 1 l l Egtgyt sqgroup v Neutral ID 3911 I Mal 781mg Steve Palmer Element Connectedness The Link Between Perceptual Organization amp Representation The key issues are 0 What in the stimulus is represented How to represent elements in and out of context PO defines the fundamental units and establishes the hierarchy in which they are later organized The representation of a stimulus defines its organization Example Multistability Any one stimulus can have multiple representations Each of these may respond to a different organization Thus representation and organization issues are fundamentally intertwined Roadmap to the Phenomena Methods and Findings of PO Phenomena Grouping gureground segregation multistability constancies Methods demonstration vs behavioral measures Findings Many examples but based organizational phenomena appear to govern how the rest of perception functions Theories of Perceptual Organization Lists of Laws General summarizing principles Full Blown Theories Marr s categories Computational Cognitive Neuropsychological NO GROUPING O O O O O O O O GESTALT LAWS OF GROUPING PROXIMITY SIMILAle EJEIIEZIE CLOSURE O O 0 O O O o O 0 O o O O O o 0 GOOD CONTINUATKON NEWLY PROPOSED LAWS COMMON REGION 8 Q I HHH CONNECTEDNESS LaWS of Grouping There are many many Helson 1933 Listed 114 Gestalt Laws Others estimate that over 700 have been proposed over the decades Boring 1942 narrowed them down to 14 SQSherJNE Boring s 14 Naturalness of form Figure and ground Articulation Good and poor forms Strong and weak forms Open and closed forms Dynamic basis of form I 84 RICE Boring s 14 continued 8 Persistence of form 9 Constancy of form 10 Symmetry of form 11 Integration of similars and adjacents 12 Meaningfulness of forms 13 Fusion of forms 14 Transposition of forms Boring s 14 continued Note that Boring s list of 14 omits some important principles including Good continuation Area Convexity Common fate Onesided function of contour Vagueness of These Laws Number 5 Strong amp Weak Forms A strong form coheres and resists disintegration by analysis into parts of by fusion with another form Many of these laws are a bit vague General Principle of Grouping Similarity Proximity similar location Common fate similar motion Similarity is too broad a term to be useful General Principle of Grouping Pragnanz global minimum principle return of the soap bubbles Dynamic selfdistribution if the kind of function which Gestalt Psychology believes to be essential in neurological and psychological theory Kohler 1929 De nition of Pragnanz Psychological organization will always be as good as the prevailing conditions allow In this definition the term good is undefined It embraces such properties as regularity symmetry simplicity and others Koffka 1935 building on Wertheimer Issues Entailed in Pragnanz Nature of simpli cation How much distortion to allow illusions etc at the expense of yeridicality Simplify the process of perception or the outcome Quanti cation How to Measure Simplicity Work of AttneaVe Garner Leeuwenberg Mumford How to test the claim Do our perceptions minimize complexity Is this plausible given evolution Alternative to Pragnanz Likelihood Principle From Helmholtz 1910 Definition Sensory elements will be organized into the most probable objects or event distal stimulus in the environment consistent with the sensory data the proximal stimulus Major Advocates of Likelihood Principle Helmholtz Hebb Hochberg Gregory Brunswik Rock Key Issues for Likelihood Principle Maj or Idea We organize our percepts in the way that is most likely to be correct Evolutionarily plausible Question how to determine what s most likely Brunwick Geisler Palmer How to test Challenges to Pragnanz Kanizsa many devastating counterexamples 3 2quot 2 57quot 69 in a b 3 b1 3 8 E23 r m l I V 139 x mquot a b M M 113 3st I 95 RICE K Challenges to Pr ignanz Attneave Rock the search for symmetry If symmetry is so important Why is our search for it so brief and unsuccessful Challenges to Likelihood Impossible Figures a e A m l 97 s RICE Could a Pragnanz Bias Be Useful Attneave 1982 Likelihood Principle can accommodate Pragnanz Simplicity is a diagnostic property of stimuli If a stimulus can be organized simply that is probably the correct organization Cf Symmetry parallelism as a nonaccidental property Attneave s Point A possible distal source that contains certain regularities is more probable than one that does not or one that contains them to a lesser degree His idea was subsequently echoed by Rock Pomerantz amp Kubovy and Palmer Palmer Simplicity acts as a surrogate for likelihood since simple organizations are likely to be correct Mach 1906 The Visual sense acts therefore in conformity with the principle of economy and at the same time in conformity with the principle of probability 2 l 100 RICE Philosophical Issues in Perception Basic Facts about Perception Philosophical Issues in Perception Three key questions 1 Mindbody relationship 2 Origins of knowledge 3 What is to be explained Free will vs determinism Reductionism and emergent phenomena Functionalism hardwaresoftware bodymind Philosophical Issues in Perception Mind body problem Is mind matter Does mind matter Monism mind and body are one mindmatter Materialism idealism radical skepticism Dualism mind and body are two separate entities lnteractionism epiphenomenalism Philosophical Issues in Perception Epistemology origins of knowledge Four possibilities 1 The Oracle 2 The environment 3 Our genes 4 Nowhere Realism critical vs naive What must be explained Behavior phenomenology underlying processes Converging operations Mental representation Psychophysical isomorphism complementarity Basic Facts about Perception Perception ls limited ls selective Requires memory Is not entirely veridical trustworthy Takes time Corresponds more to the distal than to the proximal stimulus Involves the active organization of sensory information Focuses on change not on steadystate Involves both bottomup and topdown processing Ols based on our brain s model of the world CDO ILOONA OOI Basic Facts about Perception 1 Perception is limited We detect only a slim portion of the information and energy around us Frequency Spectrum Infrared Scene What is this Powers of Ten Edgerton Bullet Galloping Horse UNITED STATES FREQUENCY ALLOCATIONS THE RADIO SPECTRUM 4 UNEMIEH MM 3mm 3mm MM Il FRARED VISIBLE ULTRAVIO r sible U Uam ale i In ated lt msz 10qu 1er 90th 1 Perception is limited Freguency Sgectrum Ultraviolet vs Visible light What is this Powers of Ten Edgerton Bullet Galloping Horse Visible 1 Perception is limited Freguency Sgectrum Ultraviolet scene What is this Powers of Ten Edgerton Bullet Galloping Horse In39ttl fuller I zu an 1hr I ll nu manum hlilii l l IE 39 ll 1 Perception is limited Freguency Sgectrum Ultraviolet scene What is this Powers of Ten httpmicromagnetfsueduprimerjavascienceopticsupowersof10indexhtml Edgerton Bullet Galloping Horse 1 Perception is limited Freguenoy Sgectrum Ultraviolet scene What is this Powers of Ten Edgerton Bullet Galloping Horse 1 Perception is limited Freguency Sgectrum Ultraviolet scene What is this Powers of Ten Edgerton Bullet Galloping Horse Leland Stanford hired Eadweard Muybridge 1872 Photographs by Eadweard Muybridge Basic Facts about Perception 2 Perception is selective Of that information we do detect we can attend to only a small fraction at any one moment cocktail party phenomenon Basic Facts about Perception 3 Requires memory Advanced perceptual systems store perceptual memories and then match inflowing sensory information against those memories to allow recognition and prediction Basic Facts about Perception 4 Perception is not entirely veridical We experience illusions that reveal how normal faithful perception works Hermann Grid Spiral Illusion Simultaneous Contrast Moon illusions Optical illusions most illusions aren t optical in oriqin For more see lllusionworks wwwpbsorgwnetbrainillusionsindexhtml IIIIIIIIIII IIIIIIIIIII IIIIIIIIIIII IIIIIIIIIIIg IIIIIIIIIII3 llIlIllIlllg IIIIIIIIIII llIIIIIIIII IIIIIIIIIIIQ IIIIIIIIIII IIIIIIIIIII Scintillating Grid Schrauf Michael Lingelbach Bernd amp Elke V st Eugene 1995 Simultaneous Contrast Simultaneous Contrast Moon IUSion since the 7th century BC Moon a zenith True path of moon Percelved path of moon Moon on honzon FIGURE 25 Iixphuzulnn Ol39 Lllu Innnn illllamn h1llt d on percen ud ilisluncc First theory of moon illusion Ptolemy 17m century Basic Facts about Perception 4 Perception is not entirely veridical We experience illusions that reveal how normal faithful perception works Hermann Grid Spiral Illusion Simultaneous Contrast Moon illusions Optical illusions most illusions aren t optical in oriqin For more see lllusionworks wwwpbsorgwnetbrainillusionsindexhtml Basic Facts about Perception 5 Perception takes time We do not perceive the world in real time but at a slight delay as neural processing unfolds FHcker Apparent motion Metacontrast slowed down Basic Facts about Perception 6 Perception corresponds more to the distal than to the proximal stimulus We perceive the invariant properties of the world around us not the fleeting and accidental properties resulting from viewpoint illumination etc Shepard Boxtops httppsvchriceeduneuropsvcholoqvPerceptionperceptionhtml Adelson Shadow Effect httppsyluxpsychtudresdendeHkawdiverses20Materialwwwillusionworkscomhtmlshadowhtml Basic Facts about Perception 7 Perception involves the active organization of sensory information mu l ulnilnx n39 P39um mim w u i WMmum it mm quotf mam Ari 7 Perception involves the active organization of sensory information We don t receive information passively but piece it together into a model Basic Facts about Perception 8 Perception focuses on change not on steadystate information Disappearance of stabilized images Adaptation McCoIIough Effect Adaptation to steady state is the norm in perceiving both external stimuli eg brightness loudness and internal emotional states like happiness Keep staring at the black dot After a while the gray haze around it will appear to shrink Basic Facts about Perception 9 Perception involves both bottomup andtop down processing Bottom up focuses on sensory information flowing from receptors to the brain Top down focuses on hypotheses and predictions generated in the brain and on feedback from the brain back down to the receptors Mismatches between bottomup and topdown ie between what we expect to perceive and what we actually perceive attract our attention Basic Facts about Perception 10 Perception is based on our brain s model ofthe world an internal representation of distal reality It is this model that we perceive not the world itself with missing bits of sensory information filled in Attention is drawn to mismatches between our model and incoming stimulation r 439quot G d
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