Lec2 Using Space - University of California, San...
Transcript of Lec2 Using Space - University of California, San...
Lec 2UsingSpace
Cogs102A*DistributedCognition
EcologicalPerception
• Asystemsmodelthatasks:Howdoesthehuman/worldsystemaccomplishperception?
• Assumesevolvedperceptualsystemsenableperceiverstonavigate through,andmanipulate,theirenvironments.
• Operationofsystemsgenerate“Invariants”=regularitiesthatemerge wheneverahumanengagesitsvisiblespace
• Sincenaturalfunctionisofprimaryconcern,boththeory&methodaimtomaximize“EcologicalValidity”ofresearch
• Theworldisacluttered,dynamicplaceandperceiversoftenmovethemselves,sothisiswhatweshouldstudy
EcologicalPerception
J.J.Gibson:"EcologicalPerception"
Perceptionastheinteraction
betweenan
activeperceiver
anditsenvironment
EcologicalPerception
Gibsoncommissionedtoresearchhowtodesign
realisticsimulatorstotrainWWIINavypilots
Contemporaryresearchdoneincomplex,real-world
environments,w/subjectssolvingreal-worldproblems
• PROBLEM:• Howdoesanobservergetfromheretothere?• Howdoesitperceiveitsspeedanddirectionofmovement?
• SOLUTION:• Focusondestinationpointandmovesuchthatthe
OpticFlowpatternsymmetricallyexpandsfromthatpoint.
OpticFlow=whenobservermoves,environmentstreamstoorfrom“FocusofExpansion”(FOE)
• OnlyFOE (subject’sfocalpointinenv,towardswhichitismoving)isstationary
• Restofvisualenvironmentexpands asyoumoveforward(towardFOE)
• Similarly,visualenvironmentcontracts asyoumovebackward (fromFOE)
FOE
Thesepointsmoveslowly
Thesepointsmovequickly
OpticFlow=whenobservermoves,environmentstreamstoorfrom“FocusofExpansion”(FOE)
• OnlyFOE (subject’sfocalpointinenv,towardswhichitismoving)isstationary
• Restofvisualenvironmentexpands asyoumoveforward(towardFOE)
• Similarly,visualenvironmentcontracts asyoumovebackward (fromFOE)
• Theacceleration ofexpansion/contractionisdirectlydependentonmover’svelocity
• PointsclosertoFOE willmove moreslowly,
• PointsfartherfromFOE movemorequickly
So,itistheseregularitiesofrelationshipbetweenrateofexpansion/contractionanddirection&velocityofmovementthataretheInvariants inthisactivity.
OpticFlowFunction
• Thus,iffocusondestination(FOE)&movesothatOpticFlow
symmetrically expands...
• 1)Workstogetyouthere
• 2)Enablesyoutoperceiveyourrelativedistancefromallpoints(basedontheirrelativeratesofexpansion)
• 3)Enablesyoutoperceiveyourownvelocity(sinceexpansionratesareafunctionofthis)
• PROBLEM:• Howdoyoukeepfromrunningintothings?• Howdoyoucatchordodgesomethingcomingatyou?
• SOLUTION:• Adjusttrajectory(orreach/grasp)accordingtothe
RateofAngularExpansion(“Tau”)oftheobject.
RateofAngularExpansion
Whenanobjectmovesdirectlyatyou,oryoudirectlytowardit,atagivenvelocity,itsrateofchangeisanInvariant
RateofAngularExpansion
Objectexpands atanacceleratingrateatitapproachesyou
RateofAngularExpansion
Objectexpands atanacceleratingrateatitapproachesyou,contracts atadeceleratedrateasitmovesaway
AngularExpansion– "Tau"
Plus,ifobjectismovingdirectly to/fromyou,itsapparentexpansion/contractionwillbesymmetrical
Rate ofexpansion/contractiondependsonobject'svelocity
AngularExpansion– "Tau"Rate ofexpansion/contractiondependsonobject'svelocity
But,ifobjectisNOT movingdirectly to/fromyou,itsapparentexpansion/contractionwillbeasymmetrical
• PROBLEM:• Howdoyoudeterminetherelativelocation
(toyou,toeachother)of2objectsasyou(orthey)move?
• SOLUTION:
• Observeinvariantpatternsin“KineticOcclusion”(AKA“Accretion/Deletion”)
KineticOcclusion(AKA"Accretion/Deletion")
Objectthatdeletes (occludes)anotherismovinginfront ofit,ORispositionedbetweenyouanditasyoumove
Objectthatshowsaccretion (becomesmoreandmorevisibleasothermoves)isrevealedasbehind other
KineticOcclusion(AKA"Accretion/Deletion")
Atagivenvelocity,objectsclosertogether changeindeletion/accretionmoreslowly
thanobjectsfartherapart
• PROBLEM:• Howdeterminetherelativesizeandlocationof2objects
whenallyoucanmoveareyoureyes?
• SOLUTION:
• Observerelativefrequency ofthe“TextureGradient”onthesubstratethattheyocclude(hide).
TextureGradients
Man-made Natural
Allsubstrates,naturalorman-made,areperceivedasarepeatingpatternthatincreasesinfrequencyasitrecedes
TextureGradient
Man-made Natural
Invariant:Gradientsbecomehigherinfrequencyasobserver’sfocusmovesfartheraway (lowerfreq asmovescloser)
"Frequency"=#ofCYCLESoftextureperdegreeofVisualArc
TextureGradient
Invariant:Gradientsbecomehigherinfrequencyasobserver’sfocusmovesfartheraway (lowerfreq asmovescloser)
Thisinvariantallowsustojudgedistance&size
ChangeinFrequency=ChangeinDistance
NoChangeinFrequency=NoChangein
Distance
TextureGradient
IfobjectsAandBarethesamesize,ifAoccludesahigherfreq gradientthanobjectBdoes,objectAmustbe
fartheraway thanobjectB
2cycles
4cycles
TextureGradient
Ifobjectsdifferinsize,atthesamedistance,theonethatoccludes
morecycles willbeperceivedaslarger
4cycles2cycles
TextureGradient• Note:Typically,large/closeobjectsLOOM=takeupmoreofvisualfield,
butabovefactorscantakepriority(seeLAB2!)
• So,sizeanddistanceareco-constrainingfactorsinthissystem• (e.g.Asyoumayknow,see...Emmert’s Law Sp=Sr XDp)
TextureGradient
Wecanbefooled intoseeingspacethatisn’tthere,misjudgingsize,etc.byartistswhoexploittheseinvariants
TextureGradient
Wecanbefooled intoseeingspacethatisn’tthere,misjudgingsize,etc.byartistswhoexploittheseinvariants
PlusMotionParallax
SeeLAB2!
Invariants =Regularitiesinhowobjectsinenvmoverelativetooneanother
givenperceiver’sposition,movement&focus
Givenhowfundamental
– i.e.predisposed,well-practiced,vitaltoaccomplishment–
spatialcognitionis,
itisnotsurprisinghowoftenweexploitit’sregularitiesto
makeothercognitivetaskseasier…
Spatialvs.SymbolicProcessing
Shiftfromsymbolictospatial processing
• e.g.SeeSpeedBug fromLecture1
• Pilotsshiftfromusingnumberstojudgingspatialdistancefromneedleondialto“SpeedBug”marker
Track spatial juxtaposition of needle and “bug”
Spatialvs.SymbolicProcessing
Avoidingabstract,symbolicprocedures• e.g.Lave1994
• Askedtoprovide“3/4ofnormaldailyallowanceof2/3cupofcottagecheese”
• Cookfirstmumblesabouthavingtaken“calculusincollege”...
3/4X2/3?
3/4________
2/3 ?
2/3________
3/4 ?
Spatialvs.SymbolicProcessing
Howmuchis3/4ofdailyallotmentof2/3cup?
Voila!
2/3
SpatialAssociations
MemoryPalace• Usespatialsimulationofa“MemoryPalace”asmnemonicdevice
• Easiertorememberitemsassociatedwithdistinct,knownlocations
• “MethodofLoci”– FirstdescribedbyGreekphilosophers,500BC
SpatialAssociations
MemoryPalace
Fourscore&7yearsago dedicated
totheproposition
that.
a newnation,conceivedinliberty
and
allmenarecreatedequal
SpatialAssociations
Chunking• Groupsubsets>feweritemstoremember
CIAFBINCISDOD
vs.
CIAFBINCISDOD
SpatialAssociations
Cache - Putthings“intheirplace”• e.g.Dishes,towelsin
differentcupboards• Especiallywithsimilarthings• Easiertofindwhenneeded
• Organizationthenshapesbehavior• Goto“right”placetoget
Co-Locate withassociated structure• e.g.Cleandishesindryingrack,
dirtystackedoncounterorinsink
SpatialAssociations
Task-DependentOrganization
• Hand-EyeCoordination• Welearntodivergeandcoordinate
ourmodalitiesofattention
• SeeupcominglectureonTRIADICDEVELOPMENT
• Primacyof“Praxic Space”• Time-lapserevealsarea
(ventral,medial,headtolap)ofmosthandactivity
Task-DependentOrganizationACCESS
Withinreach• e.g.CookbringsallingredientsandtoolstoWorkspace (“Praxic”space)
• Allowseasy,efficientaccess,insometimestime-sensitiveprocedures
Task-DependentOrganizationACCESS
Re-Orient forbetter(safer)access• e.g.Turnhandlesofcookingpotstoward(cooler)edgesofstove
sowon’tgettoohottohandle
Task-DependentOrganizationACCESS
Locatetoolswhereactivityoccurs foreaseofaccess• e.g.Keysneardoor,sinceneedwhenleavinghouse
Task-DependentOrganizationACCESS
Locateobjectswhereactivityoccursforeaseofaccess• e.g.Productionlinew/binsofparts
Task-DependentOrganizationORDER
ArrangeaccessbasedonORDERelementswillbeused• e.g.Putobjectsinaline,intheorder theyareneeded
• Nextiseasiesttoreach,Loomsasapproach
Task-DependentOrganizationORDER
• Notetradeoffduringassembly• Canlayoutinorder or forlocationused,butnotboth…
...unlessadditionalinfoprovided
Task-DependentOrganizationORDER
Co-Locate withassociated structure• e.g.Baggerseparatesitemsbysize,weight,fragility
toorganizeeffectivebagging
Task-DependentOrganizationORDER
• e.g.Hierarchical sorting allowssearchtobe…• Limited toonelevelatatime• Directed torelevantdetails
Task-DependentOrganizationMARKING
Co-Locate withassociated structuretoinform• e.g.Oncemeasure&cutbutter,layknifeoncutsection
toID,later,whichwasmeasuredpart
Task-DependentOrganizationMARKING
CanalsousespacetomarkwhatNOTtodo• e.g.Atasettable,donotdohomework• e.g.Workerslayragacrosshothandles:Beware!
SpatialAssociations
Unusualplacement• e.g.Pillbottleonkeyboard• Especiallyincommonlyengagedlocation• Surprisemarksas“special”,noteworthy
• Increases”Salience"• Likelinessofbeingnoticed
Tothetrees!