Configural Processes in Face Recognition: No "Special" Processes Underlie the "Special Case" of Face Recognition

Tilburg University

Configural Processes in Face Recognition

Rouw, R.

Publication date: 2001

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Rouw, R. (2001). Configural Processes in Face Recognition: No "Special" Processes Underlie the "Special Case" of Face Recognition. Thela Thesis.

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ISBN 90-9014773-X

PROEFSCHRIFT

ter verkrijging vandegraad van doctor

aandeKatholiekeUniversiteitBrabant, op gezag van derector magnificus,

prof.dr. F.A. van der DuynSchouten,

inhet openbaarteverdedigenten overstaan

van een door_{het collegevoor promotiesaangewezen commissie} in de aula vande_{Universiteit opvrijdag 18 mei 2001 om 16.15}

door

Romke Rouw

geboren28_{september 1970}teHilversum

-.

Promotor:

The Controversy/NeurologicalBasis/Whichstudies areincluded and why

Chapter One - 35

Structural encoding precludes recognition offace_{parts inprosopag:nosia}

Chapter Two - 61

Paradoxicalinversion effectforfaces_{and objectsin prosopagnosia}

ChapterThree-81

Configuralface_processesin_acquiredand_{developmental prosopagnosia:}

evidence fortwo separatefacesystems?

Chapter Four - 99

Impairedface_{recognition does}not_{preclude intact whole}face _perception

Chapter Fiue - 133

Howface_{recognitionbecomes special:}

configural recognitionoffacesand_objectsin childrenandadults

Chapter Six - 185

Categorizationvs.recognitionofown-raceandother-racefaces

Conclusions - 219

I. The Controversy

The questionhowfaces,asopposed toothervisualstimuli,arerecognized has received a lotofattentionin_{recent years.}Facesare_{perhaps the mostimportant}visual

stimuli tous,presenting us with informationforestablishing andmaintainingsocial contacts. There is anintuitivelogic tothenotion that thisimportantvisual

informationisdealt withby specializedprocesses, andthat perhaps even an area of the brainisreservedforprocessing facestimuli.The degreetowhichfaces are

"special" has beenatopic indifferentresearchfields(e.g.electrophysiology,

neuropsychology, developmentalstudies, andbehavioral studies).One_{could say that} the researchfield on face recognition is in factdividedinseveral separate segments,

askingdifferentquestionsand usingavarietyof paradigms.Thereason of this disunity is thatthe_{question whether there}is_{something"special" about}faces as

stimuli intriguedmanyresearchers,from different_{theoretical and experimental}

backgrounds. Asa_{consequence of}this multiple input in theface_recognitiondebate,

it is not easy to integrate all results toaunified total. As we will show below,there

are howeversome_returningissues.

Oneparticularly striking finding infacerecognitionliteraturecomes from neuropsychological reports on"prosopagnosia"(Bodamer, 1947).Prosopagnosic

patientscannotrecognizeanindividualfacewhilerecognitionofothervisualstimuli isstillintact. The_patientcanstill_recognizethe_{personthrough}non-facial cues such as clothing or posture.Sometimes,the patientcan_{still identify}the_{person through the} face, if the face hasa_{particularstriking}feature such as a mole,aremarkable haircut, or_eyeglasses.Howeverthese_{procedures are not only odd, but}alsounreliable and

Introduction

normal_range.AsDavidoff_{and Landis (1990) have}argued,aminimum_requirement

for using thetermprosopagnosia is thatatleastthe firstvisualinput intothestream

offace_{recognitionprocesses}isintact. Onthe_{other hand, prosopagnosia}needs not be

confined to_impairedface_{memory but}is_{often accompaniedbyimpaired visual} processes as well. InfactSchweich and Bruyer (1993) havereported on the

heterogeneity ofthe_deficitandshowedthat patientsdiffer intheirabilitytoperform facedecision (recognition of theface classrather thanindividualface), visualanalysis ofunfamiliarfaces,andfamiliarface_recognition.

Differentexplanations have beenputforwardtoaccount forthispuzzling

selectivedeficit. Ofcourse,acompelling interpretation is thatthere are separate and

independentprocessesspecifically reserved forthestimulusclassoffaces. _{Damage to} these processesresults inaselectiveimpairment tofacestimuli. In itsmostextreme

form, this explanation is one ofan_impaired'facemodule'.Onealternative explanation is thatprosopagnosia is alesssevere form ofagnosia, andasfaces are

more difficulttorecognize this isthestimulusgroupsuffering most fromsuchdeficit. However, this hypothesis hasbeen_{convincinglycountered by}the_findingof double dissociations.While_{prosopagnosicpatients}are_{selectively worse with} facestimuli,

other patientsare_impairedwith_{object but not}face_recognition(Farah, 1991;

McCarthy&Warrington,1986;Moscovitch,Winocur,&Behrmann, 199D.Damasio and colleaguesput forwardthe"individuation_hypothesis" (seeMoscovitch et al., 1997;Damasio, Damasio, &Hoesen, 1982). Facerecognition requires within-class

discrimination (one face fromthe other),while_{objectrecognition}testsare between-category (discriminate a car froma_flower).These_{authors showed problems with}

subtle_{within-category discrimination forprosopagnosic patients, however other} prosopagnosic patientshaveshownintactwithin-classdiscrimination(DeRenzi,

1986). McNeil and Warrington(1993)reported afarmer suffering from prosopagnosia

thatfacerecognitionisspecial intheparticularcombinationofdemandsitposes on the_{recognitionsystem.}

The issuewhetherthereissomething'special'aboutfacestimulicannot be

understoodwhile it isnotclearwhich arethe processesinvolved infacerecognition. Behavioral datafrom_{normal participants}haveindicated thatface_{stimuli might} indeedbe_{processed in}adifferentmanner than_object(non-facial) stimuli. The most

well_{known behavioral finding is}the "face inversioneffect";_{recognition of}faces is

more impaired by inverted (upsidedown)presentation thenisrecognitionofother

stimuli.Theexplanationprovided forthis finding (see Yin, 1969) is thatbesides a

general factor offamiliaritymaking mono-orientedobjects (suchasfacesand_houses)

more difficultto recognizeupsidedown,there is anadditionalfactorofincreased

difficulty only forfaces. The_{additional difficulty for}facestimuliwouldberelated to

theparticular importance ofconfigural information infacerecognition. Presenting a stimulus upsidedownhindersextraction of_configuralinformation,while_{analysis of}

isolatedfeatures is_{relativelyspared.}Other stimulusclassescanstillbe_recognized

fairly wellusing this featuralinformation, butfacerecognitionisseverely disturbed.

Similarly,otherbehavioralfindings of differentpatternsofperformance with face thanwithobjectstimuliaregenerally explained assomehow related to face recognition depending moreoninformation ofthewholeface _{configuration,}while

recognitionofotherstimuli canusefeatures or_parts-basedinformation._{One example}

of abehavioraleffectsupporting this notion is thefacecontexteffect(Homa, Haver, &

Schwartz, 1976; see alsoSuzuki&Cavanagh, 1995)whereanormal upright face

contextaids_{recognition of a facepart.}TanakaandFarah(1993)found thatthiseffect of contextwasstronger with face thanwithother_(house)stimuli. Afterlearning

wholefacesorhouses,_{recognition of only a part was more}difficultthan recognition

ofthewhole stimulus, but thiseffectwasfound stronger with face thanwithhouse

Introdtiction

Farah (1990) hasput forwardaclearmodel, witha_dichotomybetween face

recognition depending moreon 'holistic'(whole-based)informationandobject recognition depending moreon featural(parts-based)information. In

neuropsychology, suchsimilar assumption explains prosopagnosiaas_impaired

configuralprocesses(Levine &Calvanio, 1989). The opposite case ofonlyspared

configuralprocessesthen predictsagnosiawithoutprosopagnosia,whichhasindeed

been_{reported (Moscovitch et al., 1997). In this}thesis,this assumption ofastrict

divisionbetween_configuralface_{recognitionprocesses on the one handand} parts-based objectrecognitionprocesses on theother handwas testedin different

paradigms.

If thereisnothing "special" aboutthestimulusclassoffaces, thefacespecific

findingsmustreflectafailuretopresentthecorrectcontrolstimuli.Inthesemodels

notthestimulusclassoffacesitself,butratheracombinationofstimulus properties underlies the way in whichfacesarerecognized.There aretwo characteristics that

clearly emerge intheliteratureas_{being mostimportant.}Thefirst isthe_{expertise we}

all holdforfaces, and the second is the factthat recognition or matchingofindividual faces_{requires within-class}discrimination.Inthesemodels, it hasbeen suggested

(Diamond&Carey, 1986; Rhodes&McLean, 1990)that extractionof"norm-based"

("second-order relational")information isan_{importantcomponent ofexpertise with}

within-classdiscrimination ofa_{homogeneous stimulus}class.This norm-based or second-order relationalinformation is not onlytheconfiguration of thefaceitself, but moreover how this configuration deviates from the mean (orprototypical)

configuration ofthestimulusclass. We areall experts in recognizingfaces, and the

stimuliare alike (i.e. thememberssharea_{configuration),causingparticular}

importance of configuralinformation infacerecognition.Thus,opposite to the "face

the position that thefacestimulusclassitselfisspecial, is thequestion whether it is

possible tofindobjectstimuli with which thesame_{behavioral, neurological and}

neuropsychological findings canbeobtained.

Findingthe exactright controlobjects tocompare withfacestimulihasproven

problematical. Itis_{alwayspossible}to_explainthedifference_{between face and object} stimuli as asideeffectofchoiceof_{control object (it does not contain}the_right

combinationof_{stimulus properties). Similarly, it}isdifficulttodiscusswhether

different_{or separate processes}areinvolved in_{the "special case"}of_{faces as long as it}

is not yetclearwhich_{exactly are the processes}involved inface_{recognition. The main} focus inthis thesistherefore istoprovidea better picture onthevisualprocesses

involved inface_{recognition. Subsequently}the_{question can}be asked whetherthese

processesareinvolved inobjectrecognition as well, orarereservedexclusively for

thestimulusclassoffaces. Ifthe processes are reservedforfaces, aswe explained above,thiseitherreflectsaneffectofstimulus_{class per se (a face}module), or is a

consequence of thespecificstimulus properties combined in aface image.Particularly

thefactors"within-class processing" and "expertise"areassumed essential

underlyingthese processes. Thus,in_studyingthevisual_processesinvolved in face recognition, alsothe influence or importance ofthesefactors is considered.

Aswillbecome clear_{when reading}the_{followingchapters, the role of}

"configural" processes inface recognition andfacematching is a main issue in this thesis. Infacerecognition literature, "configuration- is assumedofcritical importance

infaceprocessing, asopposed to"parts-based" or"featural"information.

Unfortunately, usingtheseterms necessitatesdisentanglingthedifferent terminology

and definitions used in previous research.To_{avoid confusion, please note that}

"configural" canrefer tobothinformationandprocesses.First asalsoexplained in the introduction of Chapter 5 and Chapter 6, the term "configuration" is usedtorefer

Introduction

prosopagnosicpatient LH withnormaluprightfaces thanwithinvertedfaces is a

disruptinginfluence offace_{configuration on matching performance.}Second, there is

a question ofwhatvisualprocesses areinvolved inextractinginformation from the facestimulus.Differentnotions onwhat_{these processes}are,isreflected in the use of differentterms suchas"whole-based" or "holistic"and "configural". Intheliterature isnotalways made clear what arethedefinitions oftheseterms and how they are separate from eachother. Furthermore, itisdifficulttodetermine inacertain task whether one ortheother kindof information is used.Forexample,disturbing

relational information by moving afacefeaturealsodisturbsthe"whole face" information.Vice versa,_{contrasting presentation of a face part}with wholefaces not

only manipulates the presencevs. absenceof"holistic"information, but also that of relationalinformation. In ourexperiments we often donotdifferentiate between relational (configural) informationand_{holistic (whole-based)} information.Toavoid confusion, simplythecontrast is made between on the one hand processing of the whole stimulus,therelations betweenthe_{parts, and}the_{relations between parts and}

whole, and ontheother handtheisolated parts or stimulusfeatures.

II. NeurologicalBasis

Each chapter inthisthesisstarts withanintroduction ofthespecificresearchquestion

at hand._Thoughliteratureofimmediaterelevanceis_{discussed, the space is too}

limitedtoprovide a moreextensive discussion.In particular, intheintroductions of

thechapters thereislittle discussion oftheextensive researchfield on the

neurologicalbasis of facerecognition. This subject thoughofclearimportance in the broaderfieldof_{understanding}face_recognition,receiveslittleattention in the

and moreovertoindicatetheparallels between questionsraisedand theories

proposed in thisfield with theonesdiscussed inthefollowingchapters of thisthesis,

a short discussion of thisresearchfieldisprovidedbelow.

Area Responding Specifically to Faces?

Recentimagingstudiesreported "faceselective" activation inthefocalregion of the

fusiform gyrus, andtermed this areathefusiform face area or "FFA" _(Ishai,

Ungerleider,Martin,Maisog,& Haxby, 1997;Kanwisher, McDermott, & Chun, 1997;

McCarthy, Puce, Gore,&Allison, 1997).The_{degree of}face_specificitywas_{studied by}

comparing level of activationtofaceswithlevelofactivationtootherstimuli. FFA shows stronger activationforfaces thanforletter strings(Puce, Allison,Asgari, Gore, & McCarthy,1996),flowers orassorted objects(McCarthy et al., 1997),houses

(Kanwisher et al., 1997), andscrambledfaces(Tong,Nakayama, Moscovitch, Weinrib, & Kanwisher,2000).Sergent, Ohta,andMacDonald (1992)showed inanearlier study using PET thattheactivation found in afacerecognition task but notanobject

recognition taskwaslocated inthe

right

lingualandfusiformgyrus,theright

parahippocampal gyrus, andtheanterior temporalcortex.Thisindicates that face specific activationmightbe_{found more strongly in}the_{right hemisphere.}Theissue of

right vs. left hemisphere involvementisseparate(though related) issue and will not

befurtherdiscussed here. For amore detailed discussion of lateralizationeffects, and

a viewpoint on how differentfacerecognition functions mightbeserved in the two

hemispheres, see DeGelder and Rouw (inpress),Laeng and Rouw (inpress), and de Schonen_{& Mathivet (1989).}

Introduction

Nakayama₍₁₉₉₈₎found activation inthefusiform face areatouprightor inverted

grayscale facestimuliand uprighttwo-tone"Mooney"faces.However, whenstimuli

werenolongerrecognizable as a face (thesametwo-tonefacespresentedupside

down) no FFA activationis_{found. Similarly,}Puce,Alison, Gore,and_{McCarthy (1995)}

comparedfacestimuli with stimulicontaining thesamecomponents butwiththeir

featuresrearranged.GreatestfMRIactivationtofaceswasfound inthemidfusiform

gyrus, and more posteriorandlateral (occipitotemporalsulcusandinferiortemporal gyrus). There wasnosignificant difference between right and left hemisphere activation. Presentationofscrambled facesactivateddifferentareas,namely the

lateral_{lingualgyrus and}thecollateralsulcus. The_{authors of this study conclude that}

the findings do confirm theface sensitivity ofareas but"thedegree towhich it is face

selectiveremains tobedetermined."

McCarthy et al.(1997)demonstrated intheirfMRIstudy that bothfaces and

flowers activate_{large and partiallyoverlapping regions of}inferiorextrastriatecortex. The faces_{or flowers were viewed amongnon-objectsor amongobjects.While flowers}

amongnon-objects evoked bilateralfusiformactivation, flowers among objects did not result in any flower-specific activation. Presentingfaces_{among non-objects} resultedin_{face-specificactivation in bilateral regions of}the_posteriorfusiform_gyrus.

Evenfacesamongobjectsshowedface-specificactivation (though smaller than in the

non-object presentation condition), namely in thefocalright fusiformregion.Taken

togetherthe findingsshowed activation specificallytofaces,primarily intheright

lateralfusiformgyrus.Theauthors concludethatfacesareperceivedatleast in part

by a separate processing streamwithintheventralobjectrecognitionsystem.Still, the

findingsalsoindicatethat activation to one butnotanotherclassof stimuli can also be found withotherstimuli butfacesandother areas than the "face area".

Thepossibleneurologicalbasis of face processes and the existence of face

Electrophysiologicalstudiescomparingfaceswithotherstimulihave_{reported an}

earlynegativepotential(N200)responding preferentiallytofaces but nottoother

stimuli suchasscrambledfaces,cars, and_{butterflies (Allison, Ginter, McCarty,}

Nobre, Puce, Luby, &Spencer,1994a).Thiscomponentwasrecordedatlocations in the leftand right fusiformandinferiortemporalgyri.Furthermore, electrical stimulation of thesameregion sometimes produceda temporary inability to name

familiarfaces_{(Allison et}al.,1994a). Puce et al.(1995)observed that thefacesensitive areas (inthefusiformandinferiortemporal gyri) reportedintheirfMRIstudy were approximately coextensive with thefaceareasidentified intheseelectrophysiological studies (Allison etal., 1994a;Allison etal., 1994b).Similarly, Puce et al.'sfindings

with scrambledfacestimuliwere correspondingwithevokedpotentials inthestriate

and_{peristriate cortex inresponse tohighspatial frequency stimuli such as}

checkerboards and scrambledfaces(Allison,McCarty,Nobre, Puce,&Belger, 1994b). Thesecongruentfindingsfromdifferentmethodsto measurebrain activityprovide a

particularconvincing argumentinfavor ofsome degree of "facespecificity" in the

brain.Inclinicalstudies,Puce, Allison,Spencer, Spencer,&McCarthy, G. (1997) also studied_{face-specific ERPs as well as}fMRIactivationto faces intwo_{epileptic patients}

with intracranialelectrodes. The_{early surface-negative potential (N200) and the fMRI}

activation inresponse tofacestimuliwere foundatcorresponding locations. In both patients, activationwasfoundin

right

fusiform gyri. Thetwopatients showed additional activation inthelateral cortex, one on the left side andtheother at the right side.

These_{findings provide}clearevidenceforareas of the_{brain responding more}

stronglytofaces thantootherclassesofstimuli. Thisdoeshowevernotestablish

whethertheseareas arefaceselective, andrespondexclusively tofaces.Asecond issue

is that even

if

there isaselectivebrainarearesponding exclusivelytofaces, this does

Intl'oditction

functions.Perhaps thefunctional specialization ofthebrainallowsspecificactivation tostimuli other thanfaces.

Tile finding that the FFA respondstoinvertedfacesled _{Kanwisher et al. (1998) to}

propose that thisareamightbeinvolvedin detection of theface classrather than

identification oftheindividualface.Behavioral studieshaveshown that inverted

faces aremuchharder to_{recognize (andmight}be_{recognized in}adifferent_manner)

thanuprightfaces, but_{this difference between upright}andinvertedfaces was not

reflectedin activation ofFFA. Bentin,Allison,Perez,Puce, & McCarthy (1996) reportedacorresponding finding with thefacespecific negative component (N170) responding preferentially to humanfacesandisolatedhuman_{eyes, but not to a}

variety ofcontrol stimuli. This component was not muchaffected_byalteration of the location ofthe_{inner components or by}faceinversion_{(Bentin et al., 1996). Thus, both}

theearly negative componentasface-specificactivationfound in the FFA_appears

onceastimulusis_{recognized as a face(Kanwisher et al., 1998) but is}not_dependent

on further identificationprocesses. Even if theearly component isnotrelated to

identification,later componentsmighthoweverbe.Bentin and_{Delouell (2000)} reportedbesidesthis early component (N170)alater negativefacecomponent (ranging_{between 250 and 500 ms). In line}with theirproposal thatN170 reflects an

earlystage offaceperceptionwhilethelater componentreflectslaterprocesses of

identification, they found thatthe_{early component (unlike}the_{later N400) was not}

modulated bythefamiliarity of the face, nor influenced by task (Bentin & Delouell,

2000).However, other findings point to a role of the FFA inidentificationrather than categorization or detection.Recentstudiesexaminedbrainactivi_{ty patterns in} prosopagnosicpatients, and did notfind activation in the FFA inresponse to face

stimuli._(DeGelder_{& Kanwisher,1999).However,}theactivation found in what has been termedtheparahippocampalplace area (PPA), an arearespondingtoscenes

In conclusion, in literatureclear_{support forface specific}areasis_provided.

However, this does notimply afaceselective areasurrounded by generalobject

recognitionareas. A morejust conclusion holds thatthe areas areonlyrelatively face

specific, and are moststrongly activated byfacesas_comparedwithotherstimuli.

First,studiesfound thatfaces_{activate specific}areas,butotherareasare_{activated by}

flowersandbutterflies (McCarthy et al., _1997).Second,though theareacalled

"fusiform face area"is_{reported to show}selectivefaceactivation, boththelocation

and intensity oftheactivationisinfluenced by task andevenstimulussettings. The

FFA thusresponds notselectively, but morestronglytofaces than tootherkinds of

stimuli. Althoughno clear consensus exists, facespecific processes seemlocated in

the areaoffusiformandinferiortemporal gyrus. Tentatively, we suggest that the earlyface_{negativecomponentreported in electrophysiological studies, and the}

face-specific activation in the FFA reportedin brainimagingstudiesreflectasimilar

system. Thissystemisinvolvedwithearly encoding of thefaceshape.

"Face Specific" us. "Stimulus Properties"

The_{previous overview}showed_{support for}thenotion ofa"face area" inthebrain.

The degreeofspecificitywasindicated bytherelative activation tofacesas_compared with activationintheseareastootherstimuli.Asdiscussed_{previously with}

behavioral findings,thefindings of"facespecificity" canbeexplainedeither as

reflectingthe special status of thestimulusclassoffaces (facemodule), or as a function ofa_particularcombinationof_{stimulus properties.}

Gauthier_{and colleaguesargued that}"face_{specific" activation in an area in fact} reflectsthe_{sensitivity of}theseareas tothefactorsof_expertiseandsubordinate level (within-category) matching. Thislatter factorisrelatedtolevelofprocessing

(recognizing "a face"issuperordinatetorecognizing "Jan's face"), but also to the

Introduction

compared withthe_{similarity of}an_{arbitrarygroup ofobjects.}Face_{specificfindings} are explainedasfailuretocontrolforlevelofcategorizationatwhichstimuli are typically recognized. For example, Gauthier, Tarr, Anderson, Skudlarski, and Gore

(1999) pose that both thestudy of McCarthy et al. (199DandKanwisher et al. (1997)

didnotrequire subordinate level processing ofthecontrolobjects, because the task was oneof_{passiveviewing or}because_{presentation times were}too_{short. According} to these authors, passiveviewing ofastreamoffacesandnon-face objectsresults in subordinate levelprocessingoffaces_(theindividualperson)whileobjects are processed at amorebasiclevel.Gauthierand colleaguesfound, usingobjectstimuli,

additional activationtoverifyasubordinatelevel ofapicture over its subordinate level inthefusiformandinferiortemporal gyri as wellastemporalpoles. Gauthier, Anderson,Tarr,Skudlarski, & Gore(1997)concluded"theadditionalvisual processing requiredtoaccessthesubordinatelevel ofanon-faceobject over and

aboveitsbasic level, engages theregion ofthebrain previouslydefined as the face-selective area."

Some questions arise on the processesunderlyingtheactivation level of the fusiform inferiortemporal region. Possibly themeasurementshaveincluded more than thevisualprocessesof particularimportance infaceprocessing,however, as the volumeofactivation in this area wasnotlarger inthevisual than inasemantic task.

Anotherquestion involves howthe_{regions of interest (ROI)} aredetermined. Gauthier,Skudlarski, Gore, & Anderson(2000)studied subordinatelevelprocessing

using bothaveraged andindividually definedROIs.These areas_{responded more} stronglytofacesthanobjects inapassiveviewing task. Inaword-to-object matching

task theseROIsshowedadditionalactivationtosubordinate levelobjectmatching

("sparrow")overbasiclevelobjectactivation_("bird").Furthermore,theadditional

activation offaces_{over objects did}not_{differ significantly from}theadditional

that the FFA does notrespond tofacestimuliexclusively, it also does not show that it

is a_{"subordinate level matching area". There were many}areas_{responding more}

stronglytosubordinate thanto basiclevel matching:the"visualsubordinate minus basic"condition elicited activation ofthemiddle_{and posterior fusiform gyri, but also}

theentire occipital gyri as wellasposteriormiddletemporal gyri. Finally, note that activation of the"face areas" bystimuliother thanfaces (seealsoMartin, Wiggs, Ungerleider, &Haxby,1996;Schacter et al.,1995) refutesa_{strictly modular}

explanation, but does notputasideamodelof_{relative specialization.}

Asdiscussedpreviously inthisIntroduction, the secondproperty of particular importance inthe face-objectstimulicomparison lies intheexpertise we all hold for face recognition. Does thefacespecificactivation found in the FFAincrease (or is

even dependent_on)expertise with the stimulusclass?Gauthier et al.(2000)found

indeed that bird andcar expertsshowed FFAactivity fortheir subjectofexpertise.

Furthermore, FFA activation was even foundwithnonsense objects called

"Greebles", but only

if

expertisewiththesestimuliwasacquired throughtraining

(Gauthier et al., 1999).

This brings us tothefinal point in this model, namelytheinteraction between the factors homogeneity, categorization level andexpertise.Thisinteractionisassumed necessary for "facespecific"findings toemergewithotherstimuli.Gauthier and Tarr

(1997) studied theimportance of thecombination of stimulussettingswith"Greeble"

stimuli._{Two groups, either "novices" or "experts", were presented with}a_recognition

procedurewith uprightandinvertedGreebles.Only "experts" were participants trainedwith_{Greeble gender,family}andindividualGreebles.Both noviceand_expert

participants learnedthenames of6_{parts and}6individualGreebles,_{followed by a}

recognition task oftheparts eitherinisolation,instudied configuration (the

individual_{Greeble) or}in_{transformed configuration (upper}featuresrotated). The

Introduction

and experts were faster andlessaccurate in the'isolated parts' than inthe'studied

configuration' condition,regardlessof stimulus orientation. Accuracy showed only

for_{expertspresentedwith upright}Greeblesa_{significant better performance with}

studied configuration than with isolatedparts.Ignoringthelatencyfindings(experts

weresignificantly fasterwith uprightisolated parts) in this condition,theauthors conclude thatthis replicates the objectsuperiorityeffectasmeasuredwithfaces. Further,onlyexpertsshoweda_{significantadvantage (faster responses)}ofstudied over transformed configuration, and only intheuprightcondition. Thisfinding is not

unexpected, asonlyexperts were trainedextensively with this configuration. The conclusion ofthis study was that notthestimulusclassoffaces,but_{expertise with}

visually similarobjectsproducesconfigural sensitivity.

Theoppositestandpointasserts thatfaceperception involvescognitive and neuralmechanisms_specializedfor_{processing of}thestimulusclassoffaces, and argues against anexplanation based on a combination ofstimulusproperties. Such counter argumentwas_{provided in}arecent_{fMRI study by Tong et al. (2000). They} locatedperindividual theFFA_{(Kanwisher et al., 1997), the area}responding strongest

tohuman faces but notto objects.Takingthe human face as one extreme(strong FFA

response) and objects as the_{other extreme (no}FFA_{activation), they compared}these conditionswithstimuli suchasanimalfacesandschematicfaces.The_similarity

betweenfindings inthis study and theonesarguing against modularity is that the FFA didnot_{respond in}amanner_{expectedfollowing}a _{strictly modularaccount,}

namely activation onlytohuman faces but nottootherstimuli.Thestudy of Tong et

al. contrastedwiththese studies,however, infindingFFAactivationforanimalfaces. The participants had no expertisewiththese faces, and theactivationwasfound

equally in a taskofpassivewatching as inadelayed matchingtask.Therefore, the authors argued, activation in the FFA canbefound inabsence_{of within-category}

essential for FFAactivationin_{Gauthier's model. Further, Tong etal. argued}that the

FFA responds to both featuralasconfiguralaspects ofafacial pattern: the FFA respondstoschematicfaces(only configuralinformationwithoutface features) and

to onlyeyes(featurewithoutthecontext oftheface), but is muchless_{activated by} thesestimuli thantowholefaces,catfacesorfaceswithout_{eyes.Further arguments}

againstthe"stimulusproperties" model wereprovided byKanwisher and colleagues.

Kanwisher et al.₍₁₉₉₇₎argued that FFA activation isnotrelatedtofine-grain

computationsnecessaryfor within-categorydiscrimination, as FFA activation found

with faces wasnotfoundwith discrimination ofhands.Furthermore, FFA activation isnotdependent on task, as faceFFAactivationwasequally presentin discrimination

as in passiveviewingtasks_{(asimilar finding}andconclusionwasfoundwithhouse

stimuli by Tong et al.,2000).Finally, Kanwisher argues that FFA activation is not

dependent onexpertise: whereasthereisconsiderable expertisewithalphanumeric

characters FFA responseis_{extremely low.}

An important notion ofGauthier et al. (2000) isthat within-category recognition

in interaction_{with expertise}is_importantto_{stronglyengage the FFA.}Indeed, they showedincreased FFAactivation in car andbird_experts.Kanwisher(2000)however argues "whenthefusiform face area wasdefined usingthestandardcriteria adopted

in my lab,faceareascouldbefound inthe_{righthemisphere in only 5 of the 19}

participants in this study;ofthese,the magnitudes oftheexpertise and

categorization-leveleffects arequite small, andthe response tofacesremainatleast

twiceasstrong as that totheexpert category."Furthermore,shechallenges the use of

Greeblesascontrol stimuli,asthesestimuli look likefaces.Gauthier et al. (2000)

replied to this argumentbypointing outthatwhileGreebleexperts showed

Introduction

.

In conclusion, thedebate on the exactfunctionand specificity of the "face area has notbeensettled yet. Afinalremark onthe"stimulusproperties" model is that not

asingle factorissufficienttoexplainthedifferentlevelofactivationto faces as to

objects. To find thesamelevelofactivation inthe"face area"_{to objects as}tofaces, an

interactionoffactors, orasimultaneous_{optimalsetting}offactorsisneeded. This raisestheobvious questionwhichobjects

fulfill

theserequirements. So far, it has provendifficult to find controlnon-facestimuli thatshow equally strong activation of

this area as facestimuli have.Most convincingfindingswere reported with the "Greeble" stimuli,howeverGreebles_{were specificallydesigned as "}facecontrol".

Greeblesresemblefaces not onlyintermsofsubordinate level matching orexpertise,

but also in many other stimulusfactors (nameableparts,individual as wellasfamilies

of Greebles) and even in general shape (3D surfacewith protrudingfeatures). If no "real

world"

controlobjects canbefound that givesimilarFFAactivationasfaces, the

face specificity of thisareamight intheorystillbeexplained bythe specific

combination of propertiespresentwithfaces.However,thegreat numberoffaces and

littlenumberofobjectsactivating this area would then makeitlegitimate to call it a "_{face area" .}

As in behavioralresearch, a_returningissue istherelative_{dependence on}

"configural information"(though noconsensusseemstoexist on how this term is defined).Perhapsexpertise doesnotalways lead toconfigural processing. This explanationissupported bythestudy ofTanaka andGauthier(1997)showing that

expertisewithcells or dogs does not leadtobehavioraleffects expected with "holistic

processing".TheseeffectswerehoweverfoundwithGreeble experts,indicating

thateitheradditionalstimulus propertiesare necessaryand "expertise" and

airplanes,afeatural-basedapproachleads tobetter performance thataholistic

approach.Thus,_{depending on what is more}efficient_{expertise with}somestimulus classeswillleadto increasedwhole-basedor_{configuralprocessing,}while_expertise withother stimulusclassesleadstostrongdependenceon extractionofcertain

informativedetails.

BrainModels

Underlyingthedebate of theneurologicalbasis offace_{recognitionprocesses, of} course a_{more generalquestion on}brain_organizationisaddressed. Asdiscussed

previously inthis introduction,onetheorydescribes separate andindependent"brain

modules"_{(Fodor, 1983).}Face_{recognitionprocesses have beenexplicitly}mentioned as an example ofacomponent or "module" inthebrain.Amoduleislocalized

(neurologically separate), and its functionsareinnate,separate,independent and

mandatory. Thus, not only arefacerecognitionprocessesneurologicallyseparate

(located ata_{particular brainarea),}buttherearedifferentseparateandindependent functions involved in face_{vs. objectrecognition.}

A _verydifferentnotion of howface_recognitionisbased inabrain_organization

underliesthe"object formtopologyhypothesis"_(Ishai,Ungerleider,Martin,

Schouten,&_{Haxby, 1999; Chao,Haxby, & Martin, 1999). In this model,} theventral

temporalcortex hasa_{topological arrangement}with _{continuous representation of} informationon_{objects. Therepresentations}of different_{categories are}distributed and overlapping, astheinformation is onobjectformrather thanobject class. Thus,

characteristics ofan objectcluster together.

A thirdmodelwastermed by Tarrand Gauthier (2000) the"flexible

process-map". Rather thandividingthebrainaccordingtostimulusclassorstimulus form, in

this modelareas arebestsuited foracertaincomputation orprocess.Anassortment

Introduction

experience an objectcategory recruits (viarecognitionstrategies)certain components

ofthe process map. For example,we learnto recognize faces at theindividuallevel

(for faces itisnecessary tofindsubtle differences betweensimilarobjects)while most

objects areassociated witha_{higher "basic-level" recognition.}

Obviously it is not yetclearwhichmodeldescribes mostclosely the way thebrain works.Theoverviewprovided previouslycastssomedoubt onthestrongest version ofthe"modular"_{theory, as}itmakes_{strongpredictions on}the_{separation between}

areasinvolvedrespondingtofacesandotherareasrespondingto non-faces. For one,

although the "facearea"probably respondsmoststrongly toface_{stimuli, it does show}

activationto severalotherclasses_{of stimuli as well. Similarly,presenting a face does} not leadexclusively to "facearea" _activation,butseveralareasthroughoutthebrain show activation tofacestimuli.

Further evaluation ofthethreemodelsdescribed above ismade_{difficult by the}

fact thatno_{specification}is_{provided on}thenatureof functions andinformation

processesinvolved inprocessing a face image.What functions comprise the face

module? What isthe natureof informationstoredinobjectformtopology? Which

processesconstitute the separatecomponents ofthe process map?Furthermore, it is

possible thatadifferent_degreeof_{"specificity"} or dedication tothestimulusclass of faces_mightexistfor_{separate levels}ofvisual_processesinvolved inface_recognition. However, withthe exactnature_{of information or functions involved yet unclear it is} not possibletosolvethisissue. Inthisthesisthe natureof visualprocessesinvolved in

face recognitionisstudied. Additionallythequestionisaskedwhatfactorsinfluence theseprocesses (e.g. are the processesbound tothestimulusclassof_{face, dependent}

III.Which studiesare_{included and why}

The chapters inthethesis areallsubmittedasarticles andtherefore can also be read

independently ofthewhole.The chapters areinchronological order, that is, earliestwritingfirst and thelatest last.Thisstructurewas chosen asitallows the readertofollowthelogicalcourseofdevelopmentofideasandexperiments over the years. Inthisparagraph we

will

introducethechapters of thisthesis.Wedescribe the

questionsaskedand generalparadigmused,without giving awayallresultsobtained (these are discussedin detail inthe separate chapters).

As wesaid before, studies_{were performed to study}thevisualprocessesinvolved

inface_{recognition. Thus,}the_{experiments presented toprosopagnosic patients were}

not set upasclinicalstudiesmapping outwhatunderlies this

deficit

butrather were designedto singleoutvisualprocessesinvolved infacerecognition.The'clinical'

approachwould imply thatthelevelof performanceofprosopagnosic patients is

directlycompared with that ofnormal_{(control) participants.}Instead,we studied the

pattern ofpe«ormanceoftheprosopagnosicpatients andcompared that with the patternofperformance of normal controls.Thenormalparticipants weretested to see

whether withourchoiceofstimuli and_{test settings, the expected}"normal"_pattern wouldbeobtained.

We studiedthepuzzling finding of "inversion superiority",where prosopagnosic patientsshowworse performancewith stimuli in upright than with stimuli in

inverted orientation_{(apattern opposite to that}of normal_{participants). This}

phenomenon is ofparticularinterestbecause of the_{apparent contradiction}it_poses.

The patients showimpaired performance infacematching tasks, butthedifferential

performance betweenuprightandinvertedstimuliindicatesatleast someintact

Introduction

common assumption that impairedface_{recognitionability}reflects_impaired

"configural" processes.

The effect_{of worse performance with upright than inverted}faceswasfirst reported byFarah,Wilson,Drain,and Tanaka (1995)withprosopagnosic patient LH. In Chapter 1, wefurtherstudy this phenomenonwithpatient LH.Weexamine the generality oftheeffectby presenting to LH morphed stimuli,createdfrom fusing animalandhumanfaces, inboth uprightand_{inverted orientation. Furthermore, we} presented a taskwithhumanfacestimuli, invertedfaces, and also scrambled faces (withthe eyes at theposition ofthemouth andvice versa). Theselatterstimuli are

particularly fittoexaminethephenomenon as onlytheintactvs.impaired face configuration differentiatesbetween thenormalandscrambled facestimuli. The relation betweenintactand_{impairedprocesses was}further_{studied by presenting a}

task specificallyrequiringmatching of a face part. Does thistask,encouraging a parts-based analysis,together withLH'sintactabilitytofocus on a part, help him to overcomehis_{difficulty with}normal,uprightfaces?

Intheinitialreport on inversion superiority,Farah et al. ₍₁₉₉₅₎account for the

effect as an_impaired"face_{module". Recognition of}facestimuli_{is severelyimpaired}

but processing ofobjectsornon-objects (suchasinvertedfaces) can rely onalternative routes.Ourstudies donotsupportthisexplanation ofFarahandcolleagues. In Chapter 1 weprovided logicalreasons why we did not find the "facemodule" explanation likely, andthestudies reported in Chapter 2 were designedtoprovide a

convincing empirical counter argument.We againstudiedthepattern of performance of prosopagnosicpatient LHascompared with thatofnormal controls, but this time we presented notonlyfaces but also objectsinuprightand inverted orientation. The questions onthe"specificity" ofconfigural andfaceprocessesindeed logicallyraise theinverse questionofwhetherthe processesinvolved infacerecognitionare shared

and objectsinuprightandinvertedorientation showedaninversioneffectwithobject

stimuli as well (as wasalsofound inthe famous study by Yin,₁₉₆₉₎although the inversioneffect wassmallerwithobjectsthanfaces. Doesthis indicate the use of configuralprocessesinobjectrecognition as well? Conversely,theexplanation of

impaired "facemodule"isdifficulttomaintain

if

inversionsuperiorityeffect is also

foundwith_objectsin_{Chapter 2.}

In Chapter 3, we add a new dimension tothediscussionbycontrasting a case of acquiredprosopagnosia with a caseofdevelopmental prosopagnosia, again with a particularfocusonconfiguralface_processing.The_{purpose of this study}istwofold.

Firsttheexperimentsprovidedaninteresting contrast in matching performance between thetwo patients.This againindicates thattherelationship between

configuralprocesses andfacerecognitionability is notanall-or-nothingsituation.

Whilethe_{acquiredpatient showed} inversion_superiority, the_{developmental case did}

not. This_findingindicates thatthe_relationshipbetween_{configuralprocesses and face}

stimuli may infact differ, depending on whetheratleast somenormaldevelopment

hastaken place. (This idea of how the use of configuralprocesses relates to

developmental patternwasfurtherstudied inChapter 5.) The second issue in

Chapter3involved extendingthe contrastbetween thetwopatientstorecognition of

the faceclass(superordinate levelrecognition of "a face"), rather thandiscrimination ofindividualfaces(subordinate level recognition of "John's face"). From literature on prosopagnosia, itisknownthatimpairedrecognition ofindividualfaces can be

accompaniedby intact recognition of theface_{class, and even some spared face} processingwithimpairedfacedetection(Schweich& Bruyer,1993).However, the previousstudies also assumed thatimpairedfacerecognitionisaccompanied by

parts-based processing,thereforethe recognition of a face as "aface"couldproceed

inslow_{parts-basedanalysis. These}studies were set up inamanner_{(e.g.providing}

Introduction

strategy. In ourfacedetectionstudieswe_{included tasks with very short presentation} time that donotallowafeat:ural analysisbutforcesarapid decisionbased on the

wholestimulusinstead.Though severelyimpaired inthematchingtasks, both

patients showed goodabilitytoperformthese tasks, and evenstillabovechance with 50 ms presentation time. Furthermore, thepatientsshowed averydifferent

performance pattern in thefacematching task, but thiscontrastbetween the two patients wasnotobserved in thefacedetection task.

Inthepreviousstudies, theinversionsuperiorityeffectshown by prosopagnosic patientsisinterpreted assome sparedprocessing of thefaceconfiguration. This

entailsaconclusion that is incontradiction withacommon assumption in face recognition literature, on therelationship betweenconfiguralprocesses and face

recognitionability. Ifface_{recognitionability}is_{impaired whilepatients}arestill able

to process thefaceconfiguration, thisgoesagainstthenotion thatfacerecognition

depends on whole-based orconfiguralinformation, whileobjectrecognition depends

on parts-based_{information. Furthermore, this is in contradiction with the most}

common explanation ofprosopagnosia,whichisimpaired configuralprocesses

forcingthepatienttocompletely depend on parts-based analysis instead.Chapter 4 is

aimed specifically at thisissue: Does face_{recognition depend on configuralprocesses}

while_{objectrecognition dependon parts-based processes?Similarly,} does_impaired

processing of thefacestimulus reflectaninabilityto process thefaceconfiguration?

Theexperimentspresented toprosopagnosic patient RPinChapter 4 were designed specifically totearaparttheinfluence of aface configuration_(thenormal face

stimulus) on the one hand, andamannerofprocessing(configuralvs. _{featural) on the} other hand.

Asmentionedbefore,Chapter5_{presentsdevelopmental}studies.Our_previous

divisionbetweenface_{recognitionabilityand configuralprocessingability is by} examining how thetwodevelop inrelation toeachother. If thetwo processes were the same, onewouldexpect thatthepatternofrelativedependenceonconfigural information inface_{processing does}not_{change. Rather,configuralprocessingability}

keeps pace withthedevelopment offacerecognitionability.This relationship between configuralprocessing andprocessing members ofthestimulusclassoffaces was studiedinchildand_{adult performance on visual matching}and_recognition tasks.Furthermore, we studied theassumption that childrendiffer fromadults in their recognition or perception offaces duetoinsufficient availability of configural

processes.Chapter5_directlytested whether_{children depend}onfeatural_or

parts-based processesrather than_{configuralprocesses.In contrast with previous}studies,

thattestedchildrenwithalready quitesomedevelopmentandvisual recognition experience (from 5- or6-years-old), we tested also withveryyoung children (3- or 4-years-old).

Anotherreason toincludethedevelopmental studies in thisthesis isthatchildren

andadultsnaturally differ intheiramountofexperience with processingafacial

image. Expertise has beenproposed to bean essentialfactor, with the use of configuralinformationdepending onexpertise withastimulusclass_{(Gauthier &} Tarr, 1997;Diamond&Carey, 1986). Ifthisindeed were the case, onewouldexpect that the useofconfiguralinformationincreases withage. Adults, with more

experience andthus moreexpertise than children, then show stronger dependence of configural information than children. This samerelationshipbetweenconfigural

processes,facerecognitionabilityand expertisewasexamined again, but with a very different_paradigm, in_{Chapter 6. Here, we presented Dutch}andTaiwanese

Introduction

Dixon, 1995;Levin, in_{press). The useof configuralprocesses in}face_{recognition is} reflected intheworse performancewithinverted thanuprightfaces_('inversion effect', Yin, 1969). Thehypothesis ofacloselinkbetweenface_{recognitionability,} configuralprocesses,andexpertisepredictsdependencebetweentheown-race

advantage andtheinversioneffect withtheinversioneffectlarger forownrather thanforother race of face.

Furthermore, in thisfinalchapter we returned tothe issue raisedin Chapter 3. In the study of prosopagnosic patients,tworoutes fortherecognition of thefaceclass

and therecognition oftheindividual facewere proposed. In particular, intact or impaired useofconfiguration inoneroute doesnot influencetheother route. The

cross-raceeffectpresents us withanopportunityto againexaminethisissue. Is the

better performance (higher recognition ability) with own race thanother race of face

inthematchingtaskmirrored inanown-race advantage when detecting or categorizing own-vs.other-racefaces?

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Chapter 1

Structural Encoding

Precludes

_Recognition

of

Face

Parts

in

Prosopagnosial

The extent andtheimpact_ofsparedprocessing_offacialstimuli intheprosopagnosicpatient LH is

examinedusing_{the inversion e#ect and thefacecontext e#ect. Our study}asked howthe_{deficit in}

individualface recognition isrelated to two perceptual abilities thatarespared in thispatient but

between whichthereis_{interference when both}are_{applied to thefacestimulus,}i.e.structuralencoding

Of the.filceand parts-basedmatchingprocedures. Threeexperimentsstudiedthis relationship with task

demands and stimulus properties designed to trigger the parts-based processes. In the first experiment,

human and animalfacesare presenteduprightorinverted with good performance onlyfortheinverted condition. In Experiment 2 normal participants show a clear face context effect (matching of upright

faces easier than scrambledor inverted ones) in thefullface matching task whereas in the parts matching task the face superiority effect disappears. In contrast, LH shows a face inferiority effect when

matchingfullfaces but alsowhen matchingan isolated.face part to a.face part in_afullfacecontext. The results show thatstructuralencoding_{Oftheface overrules parts-based procedures}thatcould otherwise be helpful to_{tell individualfaces}apart.

1

Introduction

Prosopagnosia isadeficit infacerecognition(Bodamer, 194D,whereby the face no

longerelicits anysense_{of familiarityalthough}the_{patient continues}to_recognize

familiarvoices or gait.Howspecifictofacesthis disorder is, isstillcontroversial,

partlybecause veryfewcasesof_{prosopagnosia have}been_{studied in such a way that}

the possibility ofat least somemild deficit inother areas like word orobject

recognition canbeentirely excluded(Bruce&Humphreys,1994;Farah, 1990;

Gauthier,Behrmann, & Tarr, 1999).Thedebate isnow broadenedbycontributions fromelectrophysiologicalstudies _(seeJeffreys, 1996) andfrombrain imaging methods (Gauthier, Tarr, Anderson, Skudlarski, & Gore, 1999;Kanwisher, McDermoth, & Chun, 1997).Recentreportshaveprovidedevidence that lossof normal face

recognitioncanmanifest itself not just as a loss ofthenormal patternofperformance

- for_{example,better performancewith upright than with}inverted faces - but as its opposite,superior performancewithinverted in contrasttouprightfaces_{(De Gelder,} 1999;De Gelder,Bachoud-Levi, & Degos,1998;Farah,Wilson,Drain, &Tanaka, 1995).In other words, thesepatientspresent us withareversal ofthe_{normal pattern.}

This datasuggests that loss offaceprocessingability isnotsimplyamatteroflosing the abilityto processacertaincategory ofstimuli_{(faces) nor}of losingacertain

processingstyle(onewhichtargetsthestimulus configuration), but thatthere is an

interaction between_damagedandintactskills.Inorder tofocus onthis interaction we refer totheintactaspects offaceprocessingas"structuralencoding" of the face. It is

important to note that in this paper theterm"structuralencoding" doesnotrefer specifically to one or another theory offacerecognition.Thepresent paper

Structuralencoding precludes recognition_{offace parts}inprosopagnosia

toapplypartsandfeaturebasedmatchingstrategies tofaces. The robustness and

generality of thiseffect isshownin three experiments.

A perspectivecommon tomany studiesofprosopagnosia is thatthedeficit is situated atthewithin-category level and thatfacecategorization itself ortheability to

make afacedecisionisintact.Interms ofthe_popularmodelofBruceand_Young (1986), loss offace recognitionabilitycorrespondsto damage to the "facerecognition

units",leaving intacttheearlierstages offaceprocessing. The factthat recognition at

the individualor exemplar leveliscritical forfacerecognition led to the

"individuation" _theoryof_{prosopagnosia (Moscovitch, Winocur,}&_{Behrmann, 1997)}

or the view that prosopagnosia isadeficitofwithin-category discriminations, defended by Damasio(Damasio,Damasio, & VanHoesen, 1982;Damasio,Tranel, &

Damasio, 1990). Like themodelofBruceand Young, thisviewassumesthatprior to individual identityrecognition, visualface processingisintactin_{prosopagnosics. The}

conceptofstructural encoding will beusedthroughoutthis papertorefer to this

initialface_{categorizationstage because it ismore general than some of}the_specific

notions advanced to explainfaceprocessing_(seefollowing)

A family of more orlessrelated theoriesofnormalfacerecognitionhasfocused

onwithin-categoryprocesses of facerecognition. A common theme is thatthewhole face is more than_{the parts,}butthere isnoconsensus as to what is_{exactlymeant by} "whole". One view is that the face

initially

consistsofclearlyseparateparts orprimary

features,whichwhen integrated give rise tothesecond-order features or to

recognition of the face asaconfiguration(thespatial relations betweentheindividual

features), as_{argued by}Rhodesand_{colleagues (Rhodes,1988;Rhodes,Brake, &}

Atkinson, 1993).Astronger claim made byFarahand collaborators, is that face recognition does not start fromtheencodingofseparatefaceparts orinitialparsing but that the faceisrepresentedholistically such thatits parts are not represented

developmentalistshaveargued that, attheentrylevel, facesareencoded thesame

way asanyotherobjectby attending totherelations betweentheparts or to the

overallconfiguration. Fromtheredevelopstheability tousesecond-order facial information, whichunderliesindividualfacediscrimination_(Carey&Diamond, 1994; Diamond &_{Carey, 1986).}As Moscovitch et al.(1997) remark,thesedifferenttheories

each address_slightlydifferent_questions.Nevertheless, fine detailsaside, each of them suggests justwhatmight be lost in prosopagnosia: loss of configuration-based

processes inthesenseofRhodes et al., loss of the facemodule or ofholistic processing

inthesenseofFarah et al., or loss of faceexpertise relatedtosecond-order representation ofindividualdifferences.

A critical questionforgrasping the differences betweenthesethreeviews concerns what is_{then spared}in_{prosopagnosia.}Ifsecond-order_or

configuration-basedprocessing is lost iswhatremainstherecognition of isolatedfaceparts? Or,

once thefacemodule is lost,arefaces processedlikeobjects, inaparts-based way? Or again, isfaceexpertise - ortheability tousesecond-order relational

information-lost butare facesstill_processedasbundlesoffirst-orderrelational_{information just}

like objects?Thislatter view isin line withthe consensus in theliterature that

prosopagnosic patients have lostthe abilitytodiscriminate betweenfaces but

continueto categorizefacesnormally. Thus,thenotionthatfirst-order information is

sparedandsecond-orderinformation is lost (in Carey'sterms) reflectsacertain

consensus_concerningthe_patternof_{spared and lost skills}in_{prosopagnosia.}

Recentstudies_{of prosopagnosic patients have looked at this}issue inmore detail, complementingtraditional clinicaltestsofintactfacedecisionwithbehavioraltasks

thathaveshown strongface-specificperceptualprocessingeffects, liketheinversion

effect innormal participants. But studieshave revealedaparadox, because some

Structuralencoding precludes recognition_offaceparts inprosopagnosia

TheParadox_OfInversion Superiority

Theinversioneffect,firstreported by Yin (1969)fornormal participants, hasoften beenreferred to as abenchmarkfor establishingnormalfaceprocessing (Yin, 1970).

Normal participantsarebetteratrecognizing, matching,and remembering a pair of faceswhentheseare_{presentedupright thanwhen upside-down (Yin, 1969).Recently} Farah et al. (1995) havestudiedtheinversioneffectin prosopagnosic patient LH.

Followingthe resultsobtainedwithright-hemisphere deficitstheprediction was that

LHwouldperform the same waywith uprightandinvertedfaces.But instead, LH showedfaceinversion superiority. Wehaveconfirmed this finding and at the same

time extended itto objectswithagnosicpatient AD_(DeGelder et al., 1998).

Subsequently thesameeffectswereobserved with LH(DeGelder, 1999). This reversedfaceinversion effectcannot bereducedtoabsence ofthenormal pattern. Thisfindingchallenges thenotion thattheability tousesecond-orderrelational information is lost andis_{subsequently compensated forbyusing intact feature-based}

routinestodiscriminatefaces.

Instead, theparadoxofinversion superiority is thatindividualfacerecognition is lost but that_{some aspects of}face_processingarestillactiveandinterferewithreliance upongeneralvisualroutinesinordertodiscriminateindividualfaces. Thus, when the

normal pattern of better performancewith uprightfacesisreversed,moreseems to be at stake than_{justspared facecategorization inthe presence of}lost second-order or within-category discrimination. Somehowthese_patientsare_{handicappedby}their

sparedfacecategorization and preventedfromusing intactparts-based processes

with faces.Thelatter_{are successfully used}withinvertedfaces but are_{clearly of no}

use to deal withanuprightface.Presumablyinverting afacemakesit object-like and no longer triggersface-specific processes,thereforegivingachancetopart-based routines.Thepresent studyreports experiments designed to testthe robustness and