methodological issues in the study of the depiction of cast shadows

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To appear in : Journal of Aesthetics and Art Criticism

Methodological issues in the study of the depiction of cast shadows A case study in the relationships between art and cognition

Roberto (asati

Summary . The relationshi!s between art and co)nition constitute a ver& wide set of lar)el&une$!lored and at ti es undefined or uch too s!eculative !roble s. The field is narroweddown b& i !osin) so e constraints. *t is !ro!osed that the de!iction of cast shadows' in itsearl& histor&' could !rovide an ideal case stud& which confor s to the constraints. This !a!eraddresses so e ethodolo)ical !roble s of the stud& of this case. A sa !le of relevantRenaissance i a)es is discussed. A t&!olo)& of de!icted cast shadows is !ro!osed u!onwhich further e !irical research could be built.

1. Shadows in paintings: the problem

+hadows in !aintin)s are an interestin)' al ost ideal case stud& for investi)atin) therelationshi!s between artistic !ractices and co)nition. The choice of this sub,ect atterconfor s to a ver& )eneral ethodolo)ical strate)&" loo% for ver& specific problems in art

production where theactual workings of !erce!tion' thou)ht and other co)nitive !rocessesnot onl& !la& a a,or role but are alsoapparent . The strate)& is e$!ected to allow thediscover& of !otentiall& fruitful interfaces between artistic wor% and co)nition- in turn' to !rovide a set of searchable questions for co)nitive science' and to redefine so e of the

ethodolo)ies used in stud&in) art.

As a atter of fact' the stud& of the relationshi!s between art and co)nition constitutes a ver&wide set of lar)el& une$!lored and at ti es undefined !roble s. *t would be advisable tonarrow down the field b& i !osin) so e constraints. These include' however not e$clusivel&"choosin) !roduction or the !roduction !erce!tion interface /vs. !urel& !erce!tuala!!roaches - widenin) the field of artistic !roducts to include de otic art /vs. one sided focuson beau$ arts - selectin) a lar)e sa !le of artwor%s' !ossibl& e$hibitin) trial and errorendeavours devoted to the solution of s!ecific !roble s /vs. direct anal&sis of anecdotal casesthat are li%el& to be biased b& !oor data selection - requirin) the involve ent of sufficientl&articulated co)nitive ca!abilities /vs. relativel& 1si !le co)nition' e.). colour co)nition butat the sa e ti e choosin) ca!abilities that are sufficientl& delineated /vs. lar)e or diffuseca!abilities' such as readin) words or understandin) narratives - and' finall&' choosin) a fieldthat is bac%ed b& substantial e !irical research on the co)nitive side /vs. )eneral s!eculations'e.). on the social role of so e artefact buildin) techniques .

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The de!iction of cast shadows falls !rett& well within the ethodolo)ical li itations listedabove. The de!iction of shadows constitutes a relativel& circu scribed !roble with richdevelo! ents. *t is definitel& a s aller to!ic than the 1lar)e or 1oversi4e issues in therelationshi! between art and co)nition /artistic !leasure' art and the e otions' !erce!tion ofre!resentational artefacts' the use of s& bols in art' the assess ent of artistic value' the use of

the bod& as a odel for understandin) artwor%s' to ention but a few . 5ar)e or oversi4eissues ra if& too uch and too quic%l& be&ond control to cover the whole of co)nition'includin) social !ractices. At the sa e ti e' shadow de!iction is a sufficientl& articulatedartistic !ractice. 2 *t involves co)nitive ca!abilities that are definitel& lar)er than 1s all or1 icrosco!ic issues such as colour !erce!tion or of the detection of s& etr&. 6oreover'shadow de!iction lies ri)ht halfwa& between !roduction and !erce!tion. *t is close to the !roduction !erce!tion interface insofar as !ainters learned to de!ict shadows and a!!eared to be sensitive to the as!ect shadows have and ou)ht to have. *n order to de!ict shadows the !ainter ust aster o!tical and )eo etric facts and !rinci!les' and ust !ut this aster& tothe service of a !erce!tuall& !lausible re!resentation. These efforts are docu ented in a vast/so far lar)el& une$!lored cor!us that a& !rovide sufficient statistical su!!ort to e !iricalh&!otheses' !rovided one can o!erationali4e the relevant variables. Finall&' there is a lar)e bod& of research devoted to shadow !erce!tion and co)nition where it is !ossible to ine datathat constitute a bench ar% for evaluatin) actual !ictorial !ractices. * turn now to so eas!ects of this research.

2. Fundamentals of shadow perception

7oth shadow !erce!tion' and the contribution of shadow !erce!tion to the !erce!tion of s!aceand ob,ects' are relativel& well studied !erfor ances of the visual s&ste ' althou)h the& arenot co !letel& understood. Research oved fro one si !le and ele)ant idea in co !utervision' the recover& of sha!e fro shadin) and relational structure fro shadows" in !rinci!le' it is assu ed that shadows and shadin)can resolve so e 3 d a bi)uities in a scenet&!icall& re!resented b& a 2 d line drawin). The !aradi) atic a bi)uities resolved b&shadin) are curvature !olarit& a bi)uities. +o e visual 2 d structures a!!ear to be indifferentas between a concave or a conve$ inter!retation' until shadin) is added that can overco e theindifference' if su!!le ented with suitable infor ation about the location of the li)ht source.3

The !aradi) atic a bi)uities resolved b& cast shadows are !ositional indeter inacies. +o evisual structures corres!ondin) to ob,ects or surfaces a!!ear to be located at an indeter inatedistance fro other structures' until their cast shadow is added that a& si)nal the relative !osition of the two structures. T&!icall&' if an ob,ect touches its shadow' then it touches thesurface the shadow is cast u!on.8

These studies ca!itali4ed on the athe atics i !licit in !ers!ective ethods and in ethodsfor drawin) shadows develo!ed b& artists after 800' and on the so!histicated reverse o!ticsstudied b& !ost 9alileian astrono ers in order to recover sha!e fro !atterns of shadows andshade on celestial bodies /in !articular' the 6oon observed throu)h a telesco!e in i !airedor li ited viewin) conditions.

*n recent &ears it has beco e increasin)l& clearer that the role of shadows in the recover& of3 d sha!e and structure' althou)h be&ond doubt in an& occasions' is so ewhat less For an assess ent of 1lar)e issues' see (asati 2002.

2 Artistic !ractices of co !arable 1si4e and relevance are line drawin) /(avana)h ::: or e !athic or

si ulational understandin) of bod& !ostures /;uivi)er 2002 .3 <on Fieandt :3=- Ra achandran :==.8 >ersten' 6a assian and >nill' ::?.

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uncontroversial in others. The possibility of recoverin) sha!e and !osition fro shadows isnot questioned. Rather' it turns out that sha!e fro shadow a& be do inated' in an& acircu stance' b& other factors. The ost relevant facts are the followin). . * !ossibleshadin) is tolerated' !rovided we can inde!endentl& reco)ni4e /or have so e access to thesha!e of the ob,ect /7ra,e' 5e))e' >ersten 2000 . 2. * !ossible shadows are not usuall&

noticed' even when the& are fla)rant /6a assian ::: . 3. And in !articular' there is thefunda ental shadow !arado$" in order for shadows to contribute to 3 d inter!retation andalle)edl& to ob,ect reco)nition' the& ust the selves be reco)ni4ed as shadows /(asati2000 ' a fact that a%es shadows less !alatable as earl& and andator& tools of visualreco)nition.

Related to the latter !roble ' an inde!endent line of research /ori)inated b& @erin) =?= and7 hler :22 concerns the !erce!tion of cast shadowsas shadows. *t a!!ears a priorireasonable that the !erce!tual s&ste ana)es to re)ister the !resence of shadows' toreco)nise the as shadows' and to /!ossibl& discount the . Bh&C +hadows are transitor&

ar%s on a surface' and ou)ht to be distin)uished fro !er anent ar%s /colour !atches'te$tural features . At the sa e ti e' the areas corres!ondin) to shadows are e$tre el& salientin the retinal distribution of lu inance- shaded 4ones are often the dar%est 4ones in the visualenviron ent. @ere the tas% faced b& vision is not !articularl& si !le' as the solution to the !roble of !erceivin) and discountin) shadows should be both robust and fle$ible" a !owerful 1shadow filter ris%s interce!tin) non shadows /ob,ect structures or !er anent !ro!erties ' whereas a wea% filter ris%s lettin) shadows !ass throu)h and co !ete with ob,ectsor else beco e !owerful attractors for attention.

ow' so e basic conditions ust be et for so ethin) to be !erceived as a shadow.. The lu inance of the shaded area ust be substantiall& wea%er than that of the

surroundin)s' and the lu inance distribution within the area and in the surroundin)s shouldfollow so e re)ular !attern.E A certain 1shadow constanc& should be !reserved' so that theshadow does not brea% down into !ieces. 2. A shadow ter inator /distin)uishin) the shadowfro the lit u! area ust be !erceived.? 3. The ter inator should not coincide with adiscontinuit& on the surface the shadow is cast u!on /be it a line' or a difference in surfacete$ture ' as a!!arentl& the visual s&ste bets on two reinforcin) ar%sG bein) an i !lausiblecoincidence' and discards the shadow inter!retation. /This is tanta ount to a )enericview!oint assu !tion for visual !erce!tion' where the view!oint has been conce!tuall&re!laced with the !osition of the li)ht source.

*t also a!!ears that the echanis s for shadow !erce!tion are !resent in ver& earl& !erce!tual

!rocessin).=

H$!eri ents !erfor ed within the so called 1ra!id search !aradi) have shownthat in earl& !erce!tual !rocessin) discountin) of shadows can be ver& effectivel& !erfor edand that it e$!loits the / /3 features of shadows. /This constitutes a !ossible resolution ofthe funda ental shadow !arado$.

Shadow Depiction

E *llustrated b& the Adelson chec%er shadow !heno enon. The shadow constanc& !heno enon needs investi)atin). * sur ise it is related to the conditions for the

!erce!tion of trans!arenc&.? >enned& :?8.= Ron Rensin%' co unication at the +hadow Bor%sho!' Huro!ean +ociet& for Philoso!h& and Ps&cholo)&'200 .

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Bhat we %now of both !erce!tion throu)h shadow and of shadow reco)nition is relevant fora%in) so e basic clai s about the de!iction of cast shadows. *f the de!iction of cast

shadows is to contribute to the ain visual !ur!ose of a re!resentational !aintin) I enhancin)the sha!e and location !ro!erties of the de!icted ob,ects I then shadow de!ictions shouldconfor to the visual strictures on the !erce!tion of real shadows. *f for shadows to !la& a

role the& ust be reco)nised as shadows' then their de!iction should a%e it !lain that the&fi)ure as shadows in the !aintin). Finall&' if the contribution of shadows to reco)nition is notstrai)htforward and has hidden co !le$ities' then discoverin) such a contribution would haveta%en so e effort b& !ainters and co)nitive !s&cholo)ists ali%e.

Jn the ver& last !oint co)nitive science eets art histor&. Jn the art historical side' three factsare worth entionin). . Attached shadow /chiaroscuro is not universall& used in de!iction' but even whenever it is astered s%ilfull&' it is not )enerall& acco !anied b& the use' letalone the asterin)' of cast shadowsIcast shadows are rare until the Huro!ean Renaissance.:

2. After the Renaissance' shadows in Huro!ean !aintin) were canonised and shadow !aintin)was the sub,ect atter of a nu ber of !aintin) treatises.0 3. 7ut above all' durin) acircu scribed !eriod in histor&' the de!iction of cast shadows has been the ob,ect of are!resentational stru))le. Painters of the earl& Renaissance a!!ear to have been fascinated b&shadows' and to have learnt over about one centur& how to de!ict the in a )eo etricall& and !erce!tuall& adequate or satisfactor& wa& /the i !ort of these nor ative notions needs' ofcourse' a discussion . (ast shadows a!!ear to have entered !aintin) on s!ecific occasionsrelated to the content of the !aintin). These contin)encies include the fact that the re!resentednarrative involves a shadow' or !ossibl& the curiosit& of so e !ainter who found a castshadow !articularl& attractive. (ultural factors and co on sense theories of li)ht a& have !la&ed a role in these earl& atte !ts. Accordin) to To&a a ::? earl& anecdotalre!resentations of co !lete and well defined cast shadows require that li)ht source be visiblein the !aintin). 2 Accordin) to +toichita ::?' earl& de!iction of shadows for ordinar& ob,ectswas set in e$!licit o!!osition to the absence of shadows for su!ernatural entities.3

These facts are interestin). *f shadow !aintin) were universall& wides!read' or the auto atic b& !roduct of so e universal !aintin) techniques' it would require a ver& )eneral level ofe$!lanation. *f' on the other hand' it were a co !letel& rando factor' it would not beinterestin) for the stud& of the relationshi!s between art and co)nition. ow' we do a!!ear tofind in the develo! ent of Renaissance !aintin) a certain s&ste atic !attern of t&!es ofshadow de!iction. *t also a!!ears that so e for of learnin) has ta%en !lace" the !ainterGsco unit& stru))led with cast shadows until so e satisfactor& eans of de!iction wereestablished and then !ro!a)ated.

: Ro an frescoes /such as the ones at Ro an <illa of Au)ustus' st centur& AD and osaics /such as the ones at<illa del (asale' Pia44a Ar erina' +icil&' 8th centur& A.D. have survived that show interestin)' if contrived'shadows.

0 +hadow !aintin) is the sub,ect of so e ono)ra!hs' a on) which 7a$andall ::E /still lin%ed to co !utervision studies ' +toichita ::? /!articularl& interested in the s& bolic uses of re!resented shadows ' and' briefl& but interestin)l&' 9o brich ::E.

6asaccio / 80 82= ' (a!!ella 7rancacci' Florence'St. Peter healing with his shadow ' ca. 82?. Artwor%sare entioned in this stud& to !rovide an illustration of the cate)ories discussed b& the te$t. *n no wa& the&should be considered as !aradi) atic.

2 (hief e$a !les are The flight into gypt / 83 b& 9iovanni di Paolo /c. 803 8=3 ' +iena' Pinacoteca' andThe Stigmatisation of St. !rancis /c. 83? 888 b& +assetta / 3:8 8E0 ' 5ondon ' ational 9aller&.3 (o entin) on 9iovanni di Paolo !light into gypt ' thereb& )ivin) a different inter!retation than the one b&To&a a quoted in the !revious footnote.

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*n su ' shadow re!resentation is an ideal case for the stud& of the art co)nition lin%. Therea!!ear to be echanis s dedicated to shadow !rocessin) and reco)nition. +hadows areaccessed b& consciousness and attention in interestin)l& different wa&s. +hadows cancontribute to so e as!ects of the 3 d inter!retation of a scene' and to reco)nition of theob,ects in the scene. There is a certain tolerance towards the !erce!tion of incorrect or

i !ossible shadows. *n order to fi)ure adequatel& in a !ictorial re!resentation' shadows ust be reco)nisable as such. +hadow de!iction has been an i !ortant challen)e for !ainters' andthere is a vast cor!us of !aintin)s' in a sufficientl& well circu scribed historical !eriod and)eo)ra!hic area' that testifies to this lar)e endeavour. This !oint' however' requires a closerloo%.

3. Renaissance shadow depiction

The ethodolo)& of co)nitive science is and the ethodolo)& of art histor& are noti ediatel& co !atible. *n order to !resent the historical facts of de!iction at a level of detailthat could be of an& use to co)nitive scientists' it would be necessar& to !rovide a firstqualitative and quantitative assess ent of shadow de!iction in the !eriod chosen. To thateffect' * sa !led a nu ber of i a)es that a!!ear to be relevant fro Harl& Renaissance.

Bhere are we headin) toC *n an ideall& co !leted stud&' we would loo% for answers toquestions such as the followin). (an we !rovide a control !o!ulation' e.). of !aintin)s withno shadows where shadows are e$!ectedC Bhat !ro!ortion of !aintin)s a%e use of shadowde!iction over the )eneral !o!ulation of !aintin)s in which shadows a& be e$!ectedC Bhat !ro!ortion of !aintin)s dis!la& shadows that are either )eo etricall& adequate' or that res!ectthe distribution of li)ht in the environ ent' or bothC (an we distin)uish t&!es of shadow thatconstitute statisticall& si)nificant deviations fro the nor so as to lead us to detect as&ste atic !attern of error that could be co)nitivel& relevantC (an we easure variancewithin the sa !leC @ow uch of variance is e$!lained as a b& !roduct of so e factorscorrelated with shadows' such as the fact that shadow casters tend to recurC Answerin) thesequestions would be tanta ount to !ossessin) a )ood ethodolo)& for quantitativeassess ents of the content of artwor%s I a hi)hl& debatable and non consensual issue. *n thisres!ect' * shall now discuss two of the ain ethodolo)ical !oints. First' the question of thesi4e and contents of the sa !le. +econd' !roble s about the cate)orisation of the sa !le.

Size and contents of the sample

Contents of the sample

The sa !le so far includes about one thousand !aintin)s and frescoes ins!ected at variouslocations' ostl& in Bestern art useu s and collections in Huro!e and orth A erica8. Allite s re)istered have been ins!ected de "isu E' as ost available !hoto)ra!hs do not conve&

8 Ari4ona 6useu of Art' Tucson- Hr ita)e' +t. Petersbur)- 9alleria de)li Kffi4i' Florence- 9alleriadellGAccade ia' Florence- 9alleria dellGA brosiana' 6ilan- 9alleria a4ionale dellGK bria' Peru)ia- 9alleria a4ionale delle 6arche' Krbino- 9alleria Palatina' Florence- 9alleria +abauda' Turin- 9allerie dellGAccade ia'<enice- 9e Llde)alerie' Dresten- 9ett& (ollection' 5os An)eles- 6etro!olitan 6useu ' ew Mor%- 6useo

Abatellis' Paler o- 6useo di (astelvecchio' <erona- ational 9aller&' Bashin)ton- Philadel!hia 6useu ofArt' Philadel!hia- Pinacoteca' +iena- Pinacoteca di 7rera' 6ilan- The Fric% (ollection' ew Mor%- Tin%er6useu ' +an Die)o.

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enou)h relevant detail /es!eciall& in ter s of li)htness contrast' and of si4e of the relevant !ortions of the i a)e .

Spatial and temporal boundaries of the population

Paintin)s included were !roduced in *tal& the etherlands and 9er an& over a centur& in theinterval 8 E E E. The !eriod has been circu scribed for historical and statistical reasons.. The few docu ented earlier cases of shadow de!iction /in Ro an and @ellenistic !aintin)

are either s!oradic' or the& do not !er it the establish ent of a sufficientl& lar)e sa !le. 2.There was a sustained interest in shadow de!iction in earl& Renaissance that )ave rise to alar)e nu ber of 1!ictorial e$!eri ents . *n those 1e$!eri ents shadows are de!icted tovar&in) de)rees of success. 3. After the Renaissance' shadow theories develo!ed that solved anu ber of !ractical !roble s for !ainters b& !ro!osin) al)orith s' and either renderedshadow de!iction routine /to so e e$tent ' or else ade it !lain that !ainters ac%nowled)edthe e$istence of an issue about de!ictin) shadows. That is' !ainters were aware of the fact thatthere was a s!ecific !roble of shadow re!resentation and a canon of techniques thataddressed the !roble .

+o e !aintin)s have been inserted fro !eriods other than Renaissance' for their historical orintrinsic interest' or to !rovide a contrast class.

*t is esti ated that a !o!ulation of about one hundred thousands *talian Renaissanceartwor%s have survived- !ossibl& half as an& fro the etherlands. This would !ut thesa !le at less than N of the total. The statistical si)nificance of the sa !le is at this sta)ehard to assess' )iven that the !aintin)s studied are those fro a,or collections' whose choiceof !aintin)s to dis!la& are li%el& to bias the sa !le towards i !ortant historical characters/and awa& fro Ode oticG art . @owever' the sa !leGs lar)e si4e a& allow for correction ofso e biases.

#atio of paintings with shadows . *n )eneral' all !aintin)s which have been found to re!resenta shadow have been inserted. ot all !aintin)s fro the concerned !eriod have shadows' andthe !resent research does not ta%e into account the ratio of !aintin)s with shadows to theoverall !o!ulation. Jnl& !aintin)s with shadows have been inserted in the sa !le. 6oreover'not all shadows are 1interestin) /at ti es' there is ,ust a hint of a shadow ' and thecorres!ondin) !aintin)s have been discarded.

$omogeneity . 9iven the nature of the sa !le and of the feature under stud& /!resence of cast

shadows ' it is hard to !rovide a easure of the ho o)eneit& of the sa !le. Paintin)s are ofvarious si4es' ade with different techniques' etc. @owever' a certain a ount of ho o)eneit&E Paintin)s are re!resented in the database b& s%etches and descri!tive /lin)uistic cate)ories. The choice of

s%etches is dictated b& / the intrinsic difficult& I a near i !ossibilit& I of obtainin) )ood !hoto)ra!hicre!roduction for !ainted shadows' /2 the choice to sche ati4e the re!resented !heno ena /followin) a traditionwhose ain re!resentative is Arnhei :?8 . The ain !ur!ose of the s%etches' however' is onl& to !in!oint alocation in the !aintin) that is worth stud&in). @ence accurate descri!tions are crucial to the establish ent of thedatabase. The s%etches the selves should not be used for stud&in) the !heno ena. The& !rovide convenientanalo) cate)ories. 7ut one should be war& of the fact that the& constitute a re!resentational ediu the selves'and this could induce new cate)ories that a& turn out to be artefacts of the theor&.The e!iste olo)& of !aintin) anal&sis and descri!tion would require a stud& in itself. Bhat is the role ofobservation and attention in stud&in) !aintin)sC Jbservation is a slow !rocess. @ow uch of it builds u!on

quic% !erce!tual !rocessin)C +o e of the re ar%s in this essa& are a%in to those of a !ainter who is learnin)shadow effects b& loo%in) at other !aintersG wor%. *s there ore than an analo)& hereC Paul Ta&lor' !ersonal co unication.



the level of descri!tion that Panofs%& / :3: ter ed 1!re icono)ra!hic " the identification ofthe types of ob,ects /tables' !eo!le and events /battles' )estures de!icted' on the basis of theviewerGs ever&da& /visuall& related beliefs about ob,ects and events of the corres!ondin)t&!es. @owever' this level is not dee! enou)h' as so e visual !heno ena of interest toco)nitive scientist could si !l& not be consciousl& 1)iven to the viewer or the artist' and

could nevertheless leave a trace on the !aintin). The viewer a& si !l& be unable to noticethat two shadows !oint in inconsistent directions' whereas at the !re icono)ra!hic level a noni !aired viewer is alwa&s assu ed to be able to describe a !aintin). To coin a neolo)is ' wecould s!ea% here of a 1sub icono)ra!hic level of descri!tion of a !aintin)sG content.

Bhen dealin) with broad classificator& cate)ories' we should ta%e into account the roleob'ects !la& in classif&in) shadows. (ertain ob,ects recur in !aintin)s as !rivile)ed shadowcasters. +o e other ob,ects a& recur as !rivile)ed screens on which shadows are cast. *n thedata structure there ou)ht to be an ite for shadow of steps and one for shadow on steps .20

As it is assu ed fro the onset that reco)nitional ca!abilities are activated when observin) a !aintin)' so e )eneral conundru s enter sta)e' related to the classification of i a)e contents'which are not s!ecific of shadows. First' it a!!ears that in so e cases the icono)ra!hic leveldeter ines the !re icono)ra!hic level. Panof%s& hi self in his / :3: )ave an e$a !le of thei !ossibilit& of s!ecif&in) the !re icono)ra!hic level on the basis of the ever&da& beliefs ofthe viewer. A certain re!resentation in a !aintin) b& Ro)er van der Be&den was deter ined b& the art historian to be a )hostl& a!!earance of the (hild' but there is no wa& of )ivin) a !ro!er descri!tion of that as!ect of the !aintin)Gs content at the !re icono)ra!hic level' inever&da& e$!erience ter s /a floatin) bab&C . +econd' even in ore undane cases' the !reicono)ra!hic level a& be si !l& underdeter ined be&ond resolution. Bitt)enstein / :E3'

3: ade this !lain with the e$a !le of the i a)e of a an who is cli bin) u! a hill" itcould as well be the i a)e of a an who is )entl& slidin) bac% downhill. Hven ore)enerall&' the whole !roble of inverse o!tics is based on the assu !tion that the 2 d i a)ecannot co !letel& s!ecif& the 3 d inter!retation. Third' and ore s!ecificall&' the labellin) ofshadows in !aintin)s is sub,ect to to! down influences or )eneral %nowled)e about factorsthat do not translate into visual features' hence is not i ediatel& readable off an ins!ectionof the !aintin). For instance' !ainted shadows a& be indistin)uishable fro !ainted crac%s'and so e conte$tual ele ents a& be necessar& to disa bi)uate the corres!ondin)confi)urations. Another e$a !le of a factor which does not show u! as a feature is the defaultassu !tion about the direction of li)ht. Met another is the assu !tion of the uniqueness ofli)ht source' which could onl& be ade e$!licit after so e discursive anal&sis of the !aintin).Fourth' a !roble arises with the notion of t&!e identit& of ob,ects' as in ,ud)e ents to the

effect that 1the sa e ob,ects a!!ear in different !aintin)s2

. Be a& be interested ins!ea%in) of the sa e ob,ect t&!e /sa&' protruding foot ' of the sa e )eo etric bod& /sa&'cylinder on cube or geon of type ! 22 . These !roble s are li%el& to affect the criteria forstructurin) the data" shadow of protruding foot is included in shadow of protruding ob'ect ' but

20 The idea is to have a %e&word that is !art of the cate)ories /Oste!G that does not license an inferential relation between the two ite s.2 As we onl& tal% of here ob,ect t&!es' this is not an instance of the t&!e#to%en a bi)uit&.22 *n the !s&cholo)ical literature' the notion of a geon /)eo etric ion" 7ieder an :=E has been used forclassif&in) solid sha!es at a level co !atible with that of ob,ect reco)nition and with that of ele ental !erce!tual !rocessin). 9eon re!resentations are ore structured than the re!resentations of solid bodies indescri!tive )eo etr&' can be )enerated in a recursive fashion' and behave co !ositionall&. 9eon anal&sis could

be another !ro isin) area for interfacin) artistic !ractices and co)nition- as a atter of fact' an& drawin)te$tboo%s !resent a technique of fi)ure buildin) that has analo)ies with /and !erha!s ins!ired )eon basedtheories.

=



should it be included in shadow of protruding geon of type ! C +o ewhat' a t&!e identit&across i a)es ust be assu ed in order for co !arisons to be ade. A wa& around this !roble is related to an i !ortant distinction between !artono ies and cate)ories /Tvers%&

::0 . Parts of ob,ects tend to be classified in a cross cate)orial wa&' that de!endin) ostl&u!on sha!es and functions. Thus' ob,ects of ver& different t&!es have handles or ar s.

Finall&' a database of !ictorial contents need not be biased towards ob,ects and !ro!erties. *ta& as well contain event t&!e or fact t&!e descri!tion" an event based descri!tion a& becontrasted with a )eo etr&#)eon descri!tions' and the relation between the two a& requirean e$a ination. After all' shadows are d&na icall& cast b& an ob,ect- shadow castin) is anintrinsicall& causal notion.23

*n s!ite of all these reservations' a sufficientl& fine )rained level of ob,ect descri!tion see sto be available that a%es it !ossible for a cate)orisation of shadows to satisf& tworequire ents" !ossibilit& of co !arison across !aintin)s' and establish ent of cate)oriesco !risin) a si)nificant nu ber of individuals.

/ii ,ormati"ity . As * entioned above' * a a%in) a substantial use of the notion of1 ista%e . There is a nor ative )ist that )uides !art of this research. +o e !ainters are heresaid to have ade errors in de!ictin) shadows. Jf course this is in no wa& an aesthetic orstron) evaluative a!!reciation" the notion of ista%e is used here onl& ethodolo)icall&' asre!resentational ista%es are the essence of !s&cholo)ical research. 6oreover' ista%es areinterestin) insofar as the& are found to be s&ste atic. There are clear cut e$a !les of area inwhich an error is li%el& to occur' such as the )eo etr& of shadows' or the lu inance ofshadow 4ones" here !aintin)s a& si !l& not confor to nor ative shadow a!!earance ass!ecified b& o!tics and !s&cholo)& of !erce!tion. There are less clear cut cases in whichshadows a!!ear stran)e but a& ,ust be !ossible I in such cases care ust be !ut intoascertainin) whether a de!icted shadow has an ecolo)ical counter!art that a& si !l& have been overloo%ed. For instance' conver)in) shadows a& actuall& occur in nature28- !ointedshadows of colu ns of or !eo!leGs le)s do e$ist in realit& when the s%& is covered /li)htco es fro an e$tended surface - trian)le or s!i%e shadows /s all trian)ular s!i%es thate anate fro the bases of ob,ects a& a!!ear sur!risin) in a !aintin)' but the& a& be !erfectl& acce!table ecolo)icall& I onl&' the& would not' in the nor ' be noticed.Painters a& have re)istered realit& in a wa& that nor all& esca!es our attention. Thissu))ests that we should be )uarded a)ainst Oobserver ista%esG' as in classif&in) a !aintin)we a& be under the illusion of %nowin) that a certain shadow is correct or incorrect.2E

/iii -hose category Finall&' we should as% ourselveswhose conce!t' whose cate)or& is the

one used for the classification. +u!!ose we have reasons to e !lo& a conce!t of shadowclimbing steps in describin) a !aintin). *s this a conce!t !ossession of which we shouldattribute to the !ainter or is it a fi) ent of our own theor&C @istorical research a& be of hel!here' b& uncoverin) written docu ents that use or define conce!ts a%in to those listed in thedatabase. @owever' it a& also be the case that !ainters have discovered cate)ories for which

23 6asaccio' St. Peter heals with his shadow ' (a!!ella 7rancacci' Florence / 82? . +ee Tal & ::? on thed&na ic structure of shadows.28 +i)norelli /c. 8E0 E23 ' !lagellation ' 6ilan' 7rera /c. 8=0 .2E Jn a ore technolo)ical side' it a& be worthwhile investi)atin) thecorrect shadows as to have a nor ative baseline and controls for evaluatin) a shadow in a !aintin). * can thin% of two ethodolo)ies here' bot of whichuse di)ital eans. / Reconstruction. *n order to obtain the correct de!iction of a shadow in a )iven conte$t we

a& reconstruct the 3 d settin) and use a (AD s&ste to cast the e$!ected shadow. /2 (ancellin). To enhancethe understandin) of the role of a )iven shadow re!resentation' it a& be worth cancellin) the shadow b& di)italeans.

:



a na e was not available or which had a different eanin). A certain a ount of trade off ise$!ected here.

4. The database structure: Shadow categories

The followin) is a first atte !t at listin) the cate)ories that are li%el& to !la& a !ro inent rolein the database. The list is based on an infor al e$a ination of the !ilot sa !le and is' at this !oint of the research' still o!en ended and in need of various chec%s. A few acro cate)ories'subsu in) finer )rained cate)ories' are hinted at in what follows.

*f we are to establish a baseline and control )rou!s' we should start fro shadowless paintings . These i a)es are useful for showin) the sli)htl& aw%ward visual a!!earance ofob,ects and s!aces when shadows are absent. Jb,ects a& a!!ear to float above the )round.The !aintin)s are not devoid of 3 d structure' but ar)uabl& this is wea%er than the structureobtained with full blown shadows. *t is interestin) to investi)ate a nu ber of shadowless !aintin)s in order to show the non obvious !resence of shadows in !aintin)s.

Bhen we loo% at the ain features of the sa !le' we find a rou)h !ri ar& and overarchin)acro cate)orisation distin)uishin) between mainly imitation shadows vs. mainly

instrumental shadows . *nstru ental shadows are ite s used to s!ecif& the !osition and thes!atial structure of ob,ects. *n an i itation shadow we can easil& reco)nise the sha!e of theshadow caster.2 * itation shadows result fro atte !ts at drawin) anecdotal shadows't&!icall& with a narrative function. The two cate)ories are obviousl& intertwined" b& i itatin)an ob,ectGs sha!e' an i itation shadow would be instru ental in showin) that sha!e. +till' thiswould not be a strai)htforward instru ental case' as it would not rel& on sha!e fro shadin)

echanis s. 6oreover' an i itation shadow can !erfor other functions' such as si)nallin)the !ortion of an ob,ect relative to a surface.A "irtuoso shadow is t&!icall& a cast shadow that either is an i itation shadow /the sha!e ofthe ob,ect is !erfectl& reco)ni4able or follows ver& closel& the sha!e of the ob,ect it is castu!on /althou)h the ob,ect a& not be reco)nisable b& loo%in) at the shadow .2?

The de!iction of a virtuoso shadow see s to !resu!!ose that the artist has devoted so eattention to the stud& of real life shadows- however' the shadow a& also have beenco !uted' not observed' b& the artist.2= *n either case' the !resence of virtuoso shadowsindicates an interest in de!ictin) shadows for their own sa%e- shadows a!!ear to have been !ainted on purpose ' !ossibl& to attract the attention of the viewer.2: 2 <ittore (rivelli /c. 8E0 E00 - +. 9iaco o della 6arca- Krbino" the shadow of the %e& !erfectl& i itates the%e&. Daniele Ricciarelli /c. E0: E ' +an 9iovanni 7attista Decollato' Turin' 9alleria +abauda /c. EE0 ' with

an interestin)' so ewhat sur!risin) i itation shadow of hand.2? 7otte)a del 8?3' San +ernardino appare di notte ' 9alleria a4ionale dellGK bria' Peru)ia.2= *n a ver& earl& /end of 8th centur& iniature b& 7elbello da Pavia /active 830 8?3 in the <isconti @ours/Florence' 7iblioteca a4ionale as described b& >irsch :?2' 1e$tre el& bold is the elaborate shadow cast onthe wall at the left b& the fi)ures' their ro!e and !lan%' and even one of the staffs' whose shadow continues overthe blue base of the wall onto the )rass /5F 3 v. . @ere the !rofile of the shadow atches the !rofile of thefi)ures as we see the ' and not as a li)ht source could see the I hence the shadow has been co !uted' notco!ied. /* a )rateful to Fabrice Teroni for this reference.2: (arlo (rivelli /c. 830 c. 8:2 ' 6adonna della (andeletta / 8:0 8: ' 6ilan' 7rera. The candle' stran)el&sus!ended in id air' or )lued to the ste!' is a stron) e&e catchin) ele ent. There are other virtuoso shadows inthe i a)e' but this one see s to be ade for tri))erin) a narration. <irtuoso shadows can be conceived of asstron) !ro !ts for conversation. H$!licit !ro !ts for conversation are not unfa iliar in Renaissance art /onartwor%s in )eneral as conversational !ro !ts see (asati 2002 . The to!os of the tro !e lGoeil fl& falls in this

)eneral cate)or&. *t is interestin) to co !are another !aintin) b& (rivelli'*irgin with Child ' ewMor%'6etro!olitan /c. 8=0 ' where the fl&Gs sha!e and si4e are inconsistent with the fl& bein) !art of the scene'whereas the shadow is inconsistent with the fl&not bein) !art of the scene.

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*n between !urel& instru ental and i itation shadows fi)ure triangle or spike shadows /0 . *t isas if once the anchorin) function was secured' the artist started e$!eri entin) with the)eo etr& of the shadow' until he found a sufficientl& convincin) sha!e. (uriousl& enou)h' anancient e$!eri ent alon) si ilar lines !roduced a less satisfactor&' but interestin) result're"erse triangle shadows ' where the shadow diver)es as it oves awa& fro the caster' and is

then abru!tl& truncated3

.Bhen we ove to instru ental /!osition deter inin) shadows' we have first and fore ost anu ber of ite s in the cate)or& ofanchoring shadows ' that si)nal the relative !osition ofob,ect and surface. The ecolo)ical contin)enc& e$!loited here is that an ob,ect touches itsshadow whenever it touches the surface the shadow is cast u!on. Absence of ob,ect shadowcontact is an inde$ that the ob,ect does not touch the surface. Anchorin) shadows areubiquitous. <er& wides!read within the cate)or& is the the e of the shadow of a sticktouchin) )round32 I and absent is the shadow of a stic%not touchin) )round- in )eneral'shadow of sus!ended ob,ects are rare.A s!urious but utterl& interestin) cate)or& is that ofmarks with no shadow feature but withan unintended shadow function . The& are not shadows but are unwillin)l& used b& the visuals&ste to locate ob,ects on the )round.33

A acro cate)or& is that of surface enhancing shadows . This t&!e of shadow infor s theviewer about the structure of the surface it is cast u!on. <er& uch re!resented within thecate)or& is the shadow of ahori1ontal ob'ect partly suspended o"er the ground and touchingit in two points - t&!icall& a bone at the basis of the (ross' or a sword l&in) on a stone' whoseshadow su))ests surface slant.38 Also !o!ular is the shadow that climbs a step /or an obstacle '

ore )enerall&- but in an& cases a ste! or series of ste!s .3E Finall&' the shadow of a protruding ob'ect /t&!icall& a foot ,uttin) out of a !edestal' or a %nife out of a table si)nallin)a ste! and the fact that the ob,ect is ,uttin) out.3 /Jther t&!ical !rotrudin) ob,ects are stic%sand antles.3? This t&!e of shadow e$e !lifies the !roble s !osed to cate)orisation b& thefact that shadows are cast b& ob,ects' and are hence conce!tuall& !arasitic u!on the . *n so ecases it would see essential to list a shadow cate)or& not onl& b& the sha!e and the functionof a shadow' but also b& its t&!ical shadow caster.

ot onl& surfaces can be enhanced b& shadows. There also areob'ect(enhancing shadows .The& usuall& are not ver& co !ellin) as shadows' but are useful to enhance the bod& a)ainstthe bac%)round.3=

30 9erola o da Treviso il <ecchio / 8E 8:? ' (risto 6orto +ostenuto da Due An)eli' 6ilan' 7rera.3 These are ainl& docu ented in Ro an osaics /+ irat' Tunisia' 3rd centur& A.D.' and Pia44a Ar erina'+icil&' 8th centur& A.D. and have an echo in the osaics of Ravenna' 6ausoleo di 9alla Placidia /82E 8E0A.D. .32 7artolo eo <ivarini / 832 8:: ' Polittico di (onversano' <enice' Accade ia / 8?E . *n two different !anelsthe stic% !ossesses and lac%s a shadow' res!ectivel&.33 Anon& ous'Triumph of 2o"e ' 6useo 7andini' Fiesole /second half of Eth centur& .38 R. van der Beiden /c. 800 8 8 'The Crucifi3ion /c. 8 0 ' Philadel!hia.3E <ittore (ar!accio / 8?3 E2 ' Presenta1ione della *ergine al Tempio ' 7rera' 6ilan.3 <ittore (rivelli' Piet4 /c. 8= ' Krbino' 9alleria a4ionale delle 6arche.3? 9iovan 7attista (a!orali' Pala di S. 5irolamo ' 9alleria a4ionale dellGK bria' Peru)ia.3= (rivelli' S. 5iacomo della )arca ' Krbino' 9alleria a4ionale delle 6arche' is the onl& case * a aware of anob,ect that hasboth a neat cast i itatin) shadowand a s all enhancin) shadow- the two shadows areinconsistent.



(o)nitivel& interestin) cate)ories co !rise a series of "ariously mistaken or inappropriate shadows . These include truncated 6incomplete7shadows 3:- shadows truncated at edges 't&!icall& shadows that do not climb a step ' sto! at a surface discontinuit&- shadows that climba step wrongly -80 film(like shadows ' where a shadow a!!ears as a su!er!osed half trans!arentfil .8 There are further ore cases in whichonly one or some of the !otential shadow casters

do in fact cast a shadow82

- cases in which there are shadows of ob'ects that ought not to cast a shadow -83 inconsistent shadows -88 shadows that bend around a corner -8E crossing shadows -8

shadows that interact poorly with the surface they are cast upon .8?

7ut not onl& nor ativel& erroneous shadows are i !ortant. There are also a nu ber of shadow e3otica ' which' li%e the virtuoso shadows' indicate the !aintersG interest I and i$edsuccesses I in de!ictin) co !le$ visual structures. Be have here shadows from multiple

sources 89 /insofar as the& do not count as inconsistent shadows - silent witness shadows 'which testif& to the !resence of an ob,ect which is not visible in the de!icted scene-8: shadowscast by an ob'ect situated on our side of the can"as - shadows castby a light situated on our

side of the can"as . /This cate)or& subsu es the !revious one for )eo etric reasons" if anob,ect situated on our side of the canvas casts a shadow inside the !ainted scene' it is becausethe source of li)ht itself is on our side of the canvas.E0 Be have' further ore' broken

shadows /shadows cast on two disconnected surfacesE -occluded shadows shadows onwater E2. A nu ber of taboos a!!ear to be widel& res!ected' as is indirectl& !roven b& the

3: Piero della Francesca / 8 8:2 ' Annonciation ' 9alleria a4ionale dellGK bria Peru)ia / 8 0 8?0 .Althou)h * listed these shadows in the 1 ista%es cate)or&' the& could !ossibl& corres!ond to an ecolo)icall&valid situation.80

9irola o 9en)a / 8? EE ' 2a )adonna col figlio; santi e dottori della chiesa ' 6ilan' 7rera' where theshadow of a sin)in) !utto does not bend followin) the ste!s.8 Do enico di Paride Alfani' Pala della Sapien1a *ecchia ' 9alleria a4ionale dellGK bria' Peru)ia' where theshadow of the <ir)in is uch too dar%. ote that Arnhei described shadows as havin) the a!!earance oftrans!arent fil s. @owever' the ecolo)ical !heno enolo)& does not see to su!!ort this descri!tion" shadowsdo not a!!ear nor all& as bein) superposed to surfaces.82 Anon& us' Adoration of the )agi ' +an Die)o.83 9iovanni +anti- +ei A!ostoli- Krbino.88 +i)norelli' !lagellation .8E (onrad Bit4 / 800 88 c ' Adoration of the )agi / 883 888 ' 9enQve' 6us e dGart et [email protected] <ivarini / 882#E3 E03#0E ' )adonna col +ambino e Santi - Krbino.8? +o e of these shadows heavil& blac%en the area the& are cast u!on. *n 9auden4io Ferrari / 8=0 E8 '

Presenta1ione di )aria ' 6ilan' 7rera' the shadow fro a character inverts the baseline lu inosit& of ste!s.8=

Piero della Francesca / 8 8:2 ' !lagellation /c. 8EE ' Krbino.8: Tarsie' Studiolo ' Krbino' where a )lass !ane su!er!osed to a colu n is al ost invisible but for the silentwitness shadow. *n recent art' !ainters have ade a deliberate use of an even ore e$tre e device' that oforphan shadows with no ob'ect to cast them /not onl& an ob,ect in the !aintin)' but ost li%el& an ob,ect toutcourt . * can thin% here of Fili!!o de Pisis / =: :E ; ,atura morta marina con la penna / :E3 ' 6ilan'7rera' where a nu ber of shadows have no ob,ect castin) the . Jbviousl&' in order to cate)ori4e the asshadows we ta%e stoc% of the fact that so e ob,ectsdo cast a shadow in the !aintin) and that the latter are quitesi ilar to the or!hans.E0 9iovanni 7ellini / 830 E ' Piet4 /c. 8 E ' 6ilan' 7rera- the shadow of (hristGs left hand indicates a li)hton our side of the !aintin).E Do enico 9hirlandaio / 88: 8:8 ' Presentation of the *irgin at the Temple / 8= 8:0 ' Tornabuoni(ha!el' +. 6aria ovella' Florence- the shadow of a flas% is s!lit over two ste!s.E2 7ia)io DGAntonio / 88E E 0 ' The +tor& of Sose!h / 8=E ' 9ett& 6useu ' 5os An)eles' which also !rovides

an e$a !le of the two !recedin) cate)ories. <ittore (ar!accio' $unting on the 2agoon / 8:0 ' 9ett& 6useu '5os An)eles' has an& reflections on water' clearl& distinct fro shadows" even thereflection of a shadow is !resent.

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stri%in) a!!earance of the infrin)e ents" thetaboo of the shadow on the body E3' ore)enerall& of the shadow on hu an or ani al fi)ure or !art of fi)ure.E8

Finall&' * shall entionunintended shadows ' that is' !arts of the re!resentation that wereli%el& eant not to be shadows but that do a!!ear as such. A on) these' the cate)or& of socalled 1crackdows ' halfwa& between shadows and crac%s.EE

(ate)ories can o"erlap . Be can find ite s that are both a trian)le shadow and a shadow thatdoes not cli b a ste!E ' or both a trian)le shadow and a shadow that cli bs a ste!E?. H$a !lesof dis!la&s inmi3ed categories are interestin) because the& confir the conce!tual role of the !ri itive cate)ories.

5. onclusions

+hadows are an i !ortant and well studied in)redient of visual co)nition. +hadow !aintin) isnot universall& wides!read' and is not the auto atic b& !roduct of so e !aintin) technique.@ence it is interestin) for the stud& of the relationshi!s between art and co)nition. To thateffect' the ethodolo)ies of co)nitive science and that of art histor& ust eet. * !ro!osed toloo% quantitativel&' but with an e&e to quantities' at earl& shadow !aintin) in the Renaissance.A first !ilot sa !le has been e$a ined" )eneral sa !lin) and cate)orisation issues have beendiscussed' and a ter inolo)& has been !ro!osed that could brid)e the )a! between cate)oriesrelevant to the art historian and cate)ories relevant to the co)nitive scientist.Fro a cursor& anal&sis of the art historical sa !le we can draw so e !rovisionalconclusions' considerin) the relevance of these findin)s for co)nitive science.First' we do a!!ear to find in the develo! ent of Renaissance !aintin) a certain s&ste atic !attern of t&!es of shadow de!iction. The !attern has a develo! ent that a& be co !ared toa for of learnin)" the !ainter' or his co unit&' stru))led with cast shadows until so esatisfactor& eans of de!iction were established and could then !ro!a)ate' )ettin) ore and

ore differentiated and so!histicated. Fro a !eriod in which onl& so e select ob,ects couldcast a shadow' we ove to the universal and al)orith icall& constructed attribution ofshadows to all ob,ects.+econd' there is a certain conver)ence on the t&!e of ob,ects that cast shadows' their !ree inence in the scene' their location. * !ortant ob,ects cast shadows' and ar)inal ob,ectsdonGt. Possibl& this si)nals !laces where attention is !ri aril& directed' to the detri ent ofother' ore ar)inal !laces.Third' shadows are t&!icall& ob,ect and s!ace enhancers and bein) subservient fellows the&are not )iven uch detailed wor%. Bhen the& )et centre sta)e' the& are usuall& de!icted so as

to i itate /hence be a reco)nitional !ro !t for the shadow caster. @owever' in these casesthe !ainter was under two co !etin) !ressures" whenever shadows were bestowedre!resentational autono &' the& ris%ed to under!erfor as instru ents to enhance other' orerelevant features of the scene.

E3 <iolated / uch later e.). b& 7ernardo +tro44i / E= 88 'Con"ito in Casa di Simeone ' <ene4ia'Accade ia.E8 <iolated e.). b& Hustachio di Saco!o di (ristoforo' Adoration of the )agi ' 9alleria a4ionale dellGK briaPeru)ia' where the shadow of ri)ht foot cli bs ri)ht foot. This is also an e$a !le of a shadow that climbs a step .EE Piero della Francecsa' Annunciation ' 9alleria a4ionale dellGK bria' Peru)ia. This is a crac%dow with no eas&disa bi)uation. (f. also 7eno44o 9o44oli / 820 8:? ' Adora1ione dei )agi / 8E: ' Florence' Pala44o 6edici

Riccardi.E 9irola o di 7envenuto / 8?0 E28 ' Piet4 ' Krbino' 9alleria a4ionale delle 6arche.E? <ittore (ar!accio / 8?2 E2 ' Disputa di S. Stefano / E 8 ' 6ilan' 7rera.

3



Fourth' There is a conver)ence of t&!es of cast shadows and t&!es of shadow casters. This'to)ether with the recurrence of the t&!es of shadows' is sus!icious enou)h' and is anindication that the !ro!a)ation of shadow re!resentations followed a si !le e!ide iolo)&'co!&in).

Fifth' we notice that so e t&!es of shadows are ore interestin) than others' such as i itationshadows' and s!ecificall& virtuoso shadows' and indicate the !ainterGs interest in shadows.+i$th ' the ore interestin) cases are those of variousl& ina!!ro!riate shadows. Thetolerancefor ista%en shadows is stri%in). @avin) first corrected for observerGs ista%es' andconsidered as outliers those shadows that do a!!ear odd but can be found in nature' a nu berof unaccounted t&!es of shadows re ain. Be /and the !ainter as a viewer of his own wor% before us can acce!t virtuoso shadows that a!!ear realistic as the& atch the visuall&available !rofile of the shadow caster' not the !rofile the caster offers to the li)ht source. Becan acce!t inconsistencies of various sorts /shadows fro ulti!le sources' shadows fro asin)le source !ointin) in inconsistent direction' selective !resence of onl& so e of thee$!ected shadows without havin) the i !ression of a disru!tion of the visual scene.+eventh' the t&!olo)& here adu brated su))ests that a lar)e nu ber of shadowli%e !erce!tualt&!es can be used to do the wor% usuall& done b& shadows.E=

Jn the art historical side' b& !ro!oundin) an investi)ation of a lar)e sa !le of i a)es thatar)inall& deal with a ver& narrow !roble ' this stud& contains a !otential criticis s of

traditional ethods of art stud&' on two accounts. First' how uch of the ethods used instud&in) art are rel&in) on the !ersonal a!!reciation of the student or on anecdotal evidenceCThe odern ethods of the social sciences /lar)e nu bers' control !o!ulations' narrowin)down of the co)nitive ca!abilities under stud& should allow for so e corrections towards a

ore ob,ective assess ent of the contents and relevance of artwor%s. +econd' in the absenceof such quantitative endeavours' which %ind of facts are described ' which facts aree3plainedin studies on artC *snGt there here' as in an& other fields of the social sciences' a !roble of amissing e3planandum C

<nstitut ,icod = bis; a"enue de 2owendal >?00> Paris; [email protected]

Research for this stud& has been ade !ossible b& a (o)nitique 9rant of the French 6inistr& of Hducation' A(*(o)nitique 2000 2P38?0' 5e rUle de la reconnaissance dans la re!r sentation !icturaleV. * benefited froco ents on an earlier version of this !a!er b& icolas 7ullot' Pascal 5udwi)' Pascal 6a assian' FranWois;uivi)er' Paul Ta&lor' +i on Thor!e' and the audiences at conferences in Toulouse and (olle)e Par%.

ReferencesA lar)e biblio)ra!h& on shadow co)nition' as well as i a)es of so e of the ite s in the sa !le' can be found atwww.shadow ill.co .

Arnhei ' R.' :?8' Art and *isual Perception ' 7er%ele&" Kniversit& of (alifornia Press.

E= As in an& other cases' !ainters a%e discoveries asante litteram !s&cholo)ists. *n our case' the& discovereda nu ber of visual conce!ts. *t ust be re ar%ed that !aintin)s are also !ro !ts for tellin) stories' for

develo!in) reasonin)s' for ar)uin). 6an& ,ud)e ents are related to !ro!ositional !ro!erties of !aintin)sGcontent.

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7a$andall' 6.' Shadows and nlightenment ' ew @aven and 5ondon" Male Kniversit& Press' ::E.7ieder an' *.' :=E' 1<isual * a)e Knderstandin)" Recent Research and a Theor& .Computer "ision; 5raphics;and image Processing ' 32 ' 2: ?3.7ra,e' B. 5.' 5e))e' 9. H. X >ersten' D.' 2000' 1*nvariant reco)nition of natural ob,ects in the !resence ofshadows ' Perception ' 2:' 3=3 :=.7 hler' >. :22' 1Die Hrscheinun)sweisen der Farben ' Sena" Fischer.

(asati' R.' 2000' 2a scoperta dell ombra ' 6ilan" 6ondadori. Hn)lish trans. b& Abi)ail Asher'The Shadow Club ' ew Mor%" >no!f' 2003.(asati' R.' 2002' 1The Knit& of the >ind OBor% of ArtG ' on www.interdsci!lines.or)' a discussion devoted toArt and (o)nition' ed. b&. 9. Jri))i and . Arhi%a.(avana)h' P. :::' 1Pictorial Art and <ision ' )<T ncyclopedia of the Cogniti"e Sciences ' (a brid)e' 6ass."6*T Press' 8= E0.von Fieandt' >.' :3=' 1Yber +ehen von Tiefen)ebilden bei wechslender 7eleuchtun)srichtun) ' Kniversit& of@elsin%i' De!art ent of Ps&cholo)& Re!orts.9o brich' H.@' ::E' Shadows ' 5ondon" ational 9aller& Publications' ::E@erin)' H.. =?=' Bur 2ehre "om 2ichtsinne: Sechs )ittheilungen an die aiserl. Akademie der -issenschaftenin -ien . 2d ed.' Bien" (. 9eroldZs +ohn.>enned&' S.6.' :?8' A Psychology of Picture Perception ' +an Francisco" Sosse& 7ass Publishers.>ersten' D.' 6a assian' P.' >nill' D.(.' 16ovin) cast shadows induce a!!arent otion in de!th ' Perception '

2 ' ? :2.>irsch' H.B.' ed. :?2' The *isconti $ours ' facsi ile edition' M" 9eor)e 7ra4iller.6a assian' P. :::' 1* !ossible shadows . <%*S ' 80 ' +8 8.;uivi)er' F.' 2002' 1Postural sense and hu an fi)ure in Renaissance art ' on www.interdsci!lines.or)' adiscussion devoted to Art and (o)nition' ed. b&. 9. Jri))i and . Arhi%a.Panofs%&' H. :3:' 1*cono)ra!h& and iconolo)& ' inStudies in <conology ' ew Mor%" J$ford Kniversit& Press.+toichita' <.' ::?' A Short $istory of the Shadow ' 5ondon" Rea%tion.Ra achandran' <.' :==' 1Perceived sha!e fro shadin) 'Scientific American ' 2E:' ? =3.Tal &' 5.' ::?' 1Fictive otion in lan)ua)e and Oce!tionG ' in 7loo ' P.' et al.' eds.' 2anguage and Space .(a brid)e' 6ass.' 6*T Press' 2 2? .To&a a' >. ::?' 1O5a Fu)a in H)ittoG di 9iovanni di Paolo riesa inata" luce' o bre !ortate ' +ullettino Senesedi Storia Patria ' (***' 8?? 8=2.Tvers%&' 7.' ::0' 1Bhere !artono ies and ta$ono ies eet ' in +.5. Tsoha4idis' ed.' )eanings and

Prototypes: Studies in 2inguistic Categori1ation ' 5ondon" Routled)e' 338 388.Bitt)enstein' 5.' Philosophische ntersuchungen . J$ford" J$ford Kniversit& Press.

This word docu ent was downloaded fro htt!"##www.worddoc$.co # !lease re ain this lin% infor ation when &ou re!roduce ' co!&' or use it.<a href='http://www.wordwendang.com/en'>word documents</a>

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methodological issues in the study of the depiction of cast shadows

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