From: AAAI Technical Report SS-92-02. Compilation copyright © 1992, AAAI (www.aaai.org). All rights reserved.
The "Philosophical"
Case Against Visual
A "Crucial" Experiment.
Images.
Peter Slezak
Center for Cognitive Science
University of NewSouth Wales
P.O. Box 1, Kensington 2033 NSW.,Australia
cogsci@spinifex.eec s.unsw.oz.au
New Focus for Imagery Debate
In their study of reasoning with diagrammaticand nondia~,rammatic representations, Larkin and Simon(1987)
are concerned with external representations
and
explicitly avoid drawinginferences about the bearing of
their work on the issue of internal,
mental
representations. Nonetheless, we mayinfer the bearing
of their work on internal representations from the
theories of Kosslyn, Finke and other ’pictorialists’ who
take internal representations to be importantly like
external ones regarding their ’privileged’ spatial
properties of depicting and resembling their referents.
Thus, Finke (1990) suggests that "perceptual
interpretive processes are applied to mental images in
much the same way that they are applied to actual
physical objects. In this sense, imaginedobjects can be
"interpreted" muchlike physical objects" (1990, p. 18).
Elsewhere he suggests that "The image discoveries
which then ’emerge’ resemble the way perceptual
discoveries can follow the active exploration and
manipulationof physical objects" (1990, p. 171).
After twenty years of controversy, the ’imagery
debate’ concerning the ’format’ of visual mental
representations is widely regarded as having become
stalled and the impasse has even led some (Anderson
1978) to conclude that the issue between pictorialism
and the ’tacit knowledge’alternative is undecidable in
principle on the basis of behavioral evidence.
At least part of the reason for the persistence of the
imagery debate has been the fact that the dispute has
centered upon alternative explanations of the samebody
of chronometric evidence. The debate has come to
appear intractable because the two contending theories
make identical predictions for chronometric evidence
and, accordingly, adducing new evidence of timedependentmeasures, as has repeatedly been done, cannot
strengthen the case for a pictorial, spatial medium
against the rival tacit knowledge theory. Thus,
experiments are needed on which the contending
accountsdeliver different predictions.
Our ownevidence concerns perceptual organization
tasks which provide unequivocal criteria of the
successful rotation, inspection and re-interpretation of
images using "recognition processes" and "shape
classification" procedures. Despite the demonstratedease
of our task under perceptual conditions, naive subjects
have generally been unable to succeed in the tasks under
imagery conditions as would be predicted on the
pictorial theory.
Of course, as historians and philosophers of science
well know, there can be strictly no such thing as a
12
"crucial experiment", since a falsified prediction can
always be blamedon one of the auxiliary hypotheses on
which any theory depends. Nonetheless, the text-book
exampleof a "crucial experiment" is the null result of
the Michelson-Morleytest of the speed of light, and I
take the null results of our owninvestigations to show
that, like the luminiferous ether, the pictorial medium
does not exist. It is in this sense that the possibility of
reinterpreting visual patterns in mental imagery has
recently emerged as new focus for the long-standing
controversy. The question of whether, and under what
conditions, novel information maybe discovered from
images may shed new light on the debate, since it
provides a new meansfor testing the properties of the
conjectured pictorial medium.andthe claimed parallel
between imageryand perception.
"Equivalence" of Imagery & Perception
Specifically, the possibility of reinterpreting an image
follows as a direct implication of the pictorial theory
which posits an "equivalence" between imagery and
perception. On the pictorial view, a mental image is
conceivedto be a "surrogate percept, allowing people to
detect somepattern or property in a rememberedscene
that they did not encode explicitly whenthey saw the
scene initially" (Pinker and Finke 1980, p. 246). It
in this sense that the uninterpreted images in a spatial
mediumare themselves supposed to be "functionally
equivalent to physical objects or events" (Finke, 1980
p. 113), and cause the same mechanismsto be activated
as in actual visual perception itself (ibid, p. 130).
Kosslyn (1987, p. 149) explains, one purpose
imagery involves "recognition processes" to discover
information which is not stored explicitly in memory
and thus we "look" at our images in a way which is
analogous to the way we look at external objects in
order to inspect them.
Divergent Predictions
By assimilating imageryso closely with vision, indeed
by claiming their "equivalence", pictorialism is
committed to predicting closely similar "perceptual"
phenomenain imagery to those found in perception
itself. It is this deep commitmentto the perceptual
character of imagery which is the source of its
vulnerability to such asymmetriesas those of Chambers
and Reisberg (1985) and our ownresults.
Thus, Kosslynsuggests that "imageinterpretation is
at the heart of the role of imageryin cognition (if one
cannot inspect imaged patterns, they are useless)"
(1988, p. 249). Hesays "The recognition mechanisms
[of vision] can be usedin imageryas a wayof accessing
stored information"(1988,p. 264)andhis modelentails
that "imagesdepict visual information, and that this
informationis interpreted by someof the samesorts of
classificatory proceduresused in classifying sensory
input during vision" (1980, p. 32). Kosslynexplains
further that "the purposesof imagery,in large part,
parallel those of vision" and"onemay’recognize’parts
and properties of imagedobjects that had not been
previouslyconsidexed"throughthe "use of recognition
processes" (1987, p. 149). The significance
reinterpretingimagesas a crucial test of the pictorial
theoryis evidentin Kosslyn’sexplicit predictions:
Theimageis formedby forcing a changeof state in
the visual buffer in the attended region, whichcan
thenbe reprocessed
as if it wereperceptualinput (e.g.,
the shape could be recategorized), thereby
accomplishingthe purposesof imagerythat parallel
those of perception.(1987,p. 155; emphasisadded)
Bycontrast with these implications of the quasiperceptual, pictorial mediumtheory, the ’tacit
knowledge’ account would predict that the reinterpretation of imagesis difficult becauseit assumes
that the mentalrepresentationsare very abstract output
of ’higher’ cognitive processes, - encodings of
conceptualizations
or beliefs and, in this sense, already
meaningfuland not requiring interpretation, - nor
susceptible of easy re-interpretation (Pylyshyn1973,
1978).
Chambers& Reisberg Negative Results
This questionof reinterpreting visual imageshad been
brought into sharp relief with the workof Chambers
and Reisberg (1985) whofound that subjects were
uniformlyunableto reverse their mentalimagesof the
familiar ambiguous
figures such as the duck/rabbitand
Neckercube. Chambers
and Reisbergsee their results as
supporting the "philosophical" argumentsfor taking
imageryto be moreconceptual and cognitive, in the
sense that they are intrinsically interpreted symbols
whichdo not ne, ed, and do not easily permit, further
interpretation. Since the close parallel, indeed
"equivalence" of imagery with the mechanismsof
perception has beenone of the central tenets of the
pictorialist theory (Podgornyand Shepard1978, Finke
1980, Farah 1988), the results of Chambersand
Reisbergare surprising and maybe seen as posing a
fundamentalchallenge for the pictorial theory. Of
course, these negative results provide experimental
supportfor the specific claims madeover a decadeago
by Pylyshyn(1973, 1978)in his critiques of pictorial
theories. Despite these earlier skeptical claims,
however, in the intervening period there has been
experimental
evidenceof just suchabilities of peopleto
detect novel properties in imaginedscenes. Pinkerand
Finke (1980) report subjects’ ability to "see" novel
properties which"can be ’read off’ the display" and
whichshould emergefromimagesafter mentalrotation.
13
Finke and Slayton (1988) have extended this work,
providingfurther evidence"that people are capableof
makingunexpecteddiscoveries in imagery" and that
novel patterns can "emerge" from within imaged
patterns.
Response by Finke, Pinker and Farah.
Most recently, Finke, Pinker and Farah (1989) have
soughtto reinforce these claimswith newexperiments
whichalso purport to showthat subjects can inspect
and reinterpret their images by "applying shape
classification proceduresto the informationin imagery"
(1989,p. 51). This latter workis of particular interest
becauseit has beenspecifically designedto counterthe
skeptical conclusionswarrantedby the negativeresults
of Chambersand Reisberg and sets the scene for our
owninvestigation. Thus,it is in the light of this clash
of experimentalresults and theoretical claimsthat our
own experiments are to be understood: Our new
experimentsavoid the specific objections by Finke et
al. andby falsifying entailmentsof the pictorial theory
in a different manner,our results can be seen as further
illuminating the precise conditions under whichsuch
seeminglycontradictoryresults can be obtained.
"Philosophical" &"Strictly Empirical"
However,
it is ultimately fruitless for the protagonists
in the imagery debate to continue counterposing
empiricalresults as if these speakfor themselves.The
cloudinessof the presentsituation andthe intractability
of the debateis symptomatic
of fundamentalconceptual
problemsrather than straightforwardempirical issues.
Finke (1989) passes over such "philosophical"
problemsand the principal alternative theory (Fodor
1975) implyingtheir relative unimportanceand saying
that "this is strictly an empiricalquestion"whichhas
beendecidedby the evidencethat "mentalimagescan be
reinterpreted" (1989, p.129). Thecited data of Finke,
Pinker and Farah undoubtedlyshowthat "imagescan be
reinterpreted", but this cannot "refute" Chambers
and
Reisbergsince it only begs the central question: What
is the reasonfor the discrepancy?
TheChambers
and Reisberginvestigation derives its
significance from showing the inability of image
reconstrual precisely under conditions in which we
wouldhaveexpectedit accordingto the quasi-perceptual
account. By demonstrating the possibility of
reinterpretationunderentirely different conditions,Finke
et al. havemerelyavoidedthe crucial issues, whichare,
moreover,the "philosophical",that is, theoretical, ones
Finkeet al., havewishedto dismiss(See Slezak 1990,
1991).
Thecommon
designation of "philosophical" for the
tacit knowledge
position by its critics is a peculiar,
thoughtelling, symptom
of the difficulties whichhave
plaguedthe debate. Thenotion of Finkeet al. (1989,
p.54) that argumentsin the philosophicalliterature on
imagery"haveno relevance"to the empirical questions
reflects someinvidious, if obscure, comparison
between
rival theorieswhichare, in fact, identical in status as
competingexplanations of the evidence.This attitude
betrays a certain vestige of positivist or behaviorist
faith in the unambiguous
deliverancesof observational
evidence. Misunderstandingon this point has led to
peremptory
dismissalof the tacit knowledge
accountand
to a systematicneglectof its explanatoryforce.
Thus, for example, Kosslyn (1980, p.30) has
described the tacit knowledgeopposition as a "no
imagery"accountas if it purportedto denythe existence
or reality of visual imagery. It is evidently this
misunderstanding
whichunderlies his tactic of adducing
further chronometric
data as if theycouldaddsupportto
his theorywhereas,in fact, they can only reinforcethe
reality of imageryphenomena
whichare not in dispute.
This approachamountsto legislating pictorialism true
by taking the evidenceto somehow
uniquelyfavour the
pictorial theory. This misunderstandingof the tacit
knowledge account is manifest in the design of
experiments which have been taken to bear on the
dispute. Thus,Kosslyn(1983)has tried to deflect tacit
knowledgeexplanations of the phenomenaby noting
that "virtually nobodyoutsidethe field knowsaboutthe
McCullough
effect" and therefore "subjects could not
have intentionally or unconsciouslyproducedthese
results withoutusing imagery"(1983, p.81).
First, however,the issue cannot be whether the
subjects used imageryas Kosslynsuggests here, since
this is not in dispute (see also Finke1990,p.19).
alreadynoted, the tacit knowledge
theory does not deny
that imageryis used by subjects, but only offers a
different explanation of it. In particular, it is no
argument against the tacit knowledge theory to
demonstrate howcontrol subjects not using imagery
give different results fromthose whodo (Kosslyn1981,
p. 238, 142). Althoughthis experimental design is
conceivedas havingempirical bearingon the debate, it
is in principle incapableof doingso. Thecontrol group
in all these cases is presumednot to be using imagery
andthereforebecomesutterly irrelevant to the disputed
question of howthe results are to be explainedin the
case whensubjects are using imagery. Patently,
controllingfor the use of imagerycan onlyestablish the
empirical importanceof imageryas a variable and does
not favourthe pictorial medium
theory - unless the two
are implicitly and illegitimately taken to be the same
question.
Furthermore, the undoubted ignorance of the
subjectsconcerningsuchexperimental
results is entirely
irrelevant to the possibility of explainingthemthrough
tacit knowledge,since there is nothing in the claim
whichrequires that the relevant beliefs be this kind of
belief. Onthe contrary, the idea of tacit knowledge
is
precisely the idea of beliefs whichare unavailableto
consciousawareness.Pylyshynhas been quite explicit
on this question, noting that "muchof it is not
introspectableor verballyarticulable"(1981,p. 161).
Theappealto tacit knowledge
is to invokewhatthe
subject knowsimplicitly about the phenomenaor
events in the world being imagined,and emphatically
not about the psychological experiment as Kosslyn
seemsto think. Nor, can the knowledgein question be
14
construedas knowledge
"of their visual systems"or of
neurophysiology
as Farahhas takenit (1988, p.314).
Equivalence
Thesis.
Wemaynote that a symptomof the problemsinherent
in the pictorial approachis evident in Finke’s (1980)
discussionwherehe speaksof "physicalobjects" instead
of percepts of physical objects. Hedescribes mental
imagesas "functionally equivalentto physical objects
or events, with respect to certain types of effects"
(,p.113). However,
it shouldbe evident that onecannot
makeany meaningful comparisonbetween images and
physicalobjectsper se, if the latter are takenseriously
andliterally as the relevant items of comparison.That
is, Finke is unlikely to be seriously concerned to
comparethe properties of mental representations as
psychologicalentities with those of tables and chairs
(see also Finke1990,p.171).
Byassimilating imageryso closely with vision,
indeedby claimingtheir "equivalence",the pictorialists
are inevitably committedto predicting closely similar
"perceptual" phenomena
in imageryto those found in
perceptionitself. As alreadynoted, the significanceof
our non-chronometrictasks as "crucial experiments"
derives from testing these direct implications of the
pictorial theory. Specifically, the experimentsare
concernedto test the ’quasi-perceptual’claimsaccording
to which "the purposes of imagery, in large part,
parallel those of vision" in "the use of recognition
processes" through which Kosslyn claims "one may
’recognize’parts and properties of imagedobjects that
had not beenpreviously considered"(1987, p. 149) The
abilities beingtested are exactlythose whichare claimed
to have beendemonstratedby Pinker and Finke (1980)
whoreportedsubjects’ ability to "see" novelproperties
whichcould emergefrom images only after they had
been mentally rotated wherenewproperties of images
"can be ’read off’ the display" (1980, p. 262). The
ability to "re-parse"an imageby usingperceptualshape
classification procedureshas beenclaimedby Finke et
al. (1989), just as Finkeand Slayton (1988) claim
have shown "that people are capable of making
unexpecteddiscoveriesin imagery".
By testing newand quite different "perceptual"
phenomena,our work shows yet further respects in
whichthe alleged "equivalence" betweenimageryand
perceptionbreaksdown.Ourexperimentscan be seen as
avoidingthe specific criticisms of Finkeet al. (1989),
and our data provide not merelya confirmationof the
negative Chambersand Reisberg results, but give a
further elaborationof the conditionsunderwhichimages
canor cannotbe reinterpreted.
Experiment la: Mental Rotation.
Newstimulus materials havebeendesignedto havetwo
distinct interpretations whichare highly orientation
specific. Thus,the figures are recognizableas a certain
object in one orientation, but are interpretable as an
entirely different object whenrotated by 90 degrees.
Thesestimuli are variants of the stimuli used by Rock
(1973), and are considerably improved in their
recognizability. In this respect, the shapes havethe
importantfeature that the alternative interpretationsare
readily obtainedby rotation underperceptualconditions.
shapeshavinganyalternative interpretation. This was
to set subjects’ expectationsfor the subsequentstimuli
whichwere, in fact, orientation-dependent
figures. For
eachpresentedfigure in turn, subjectswereaskedif they
couldrecognizeit, to nameit, andthen to memorize
it.
After 10 secondsthe stimulus figure wasremovedfrom
viewandthe subject wasaskedto imaginerotating it by
90 degrees in a clockwisedirection. Whenthe subject
confirmedthat the figure wasbeing imaginedin this
rotated position, he/she was asked if it could be
interpreted as anythingelse fromthis viewpoint.This
procedurewasrepeated with each of the orientationdependentshapesin turn.
An important methodologicalproblemarises from
the danger that subjects might encode both
interpretations duringthe original perceptualexposure
since in this case they wouldnot be relying on imagery
processesto discoverthe alternative interpretation. In
particular, it is evidentthat the problemmayarise when
subjects are set the imaginalrotation task morethan
once, since after the first one they are no longernaive
concerningthe possibility of a secondconstrual of the
figure. Onany subsequenttest, they mayUnavoidably
seek a secondinterpretationduringthe initial perceptual
exposure. This possibility can be minimized by
restricting exposure time as Chambersand Reisberg
have done to a duration which is long enough to
establish the imageand yet not long enoughto seek
alternative interpretations. However,this is a risky
proceduresince subjects whoare awareof a possible
reconstrual are frequently able to notice both
interpretations almostimmediatelyandsimultaneously.
Figure1
It is importantthat the task of reinterpretationcan
be readily accomplishedin this wayduring perception
becausethis makesthe conditionsfor reconstrualunder
imageryconditionsas favorable as possible. Thus,for
example, whensubjects are shownfigure 1 in one
orientation, it is immediately recognized as the
duckling; then uponrotating the figure by 90 degrees,
subjects immediatelynotice (with frequent expressions
of surpriseanddeligh0the alternativeinterpretation,the
rabbit.
Results. At first glance, the experimental results
appear somewhat equivocal on the question of
reinterpretation since subjects weregenerally able to
reconstrue in imaginationabout one third (35%)of the
figures they werepresented. Evenon these data it is
clear that reinterpretation of the rotated imagewas
difficult to perform, even if not always impossible.
However,these results across multiple presentations
take on a greater significance whenthe order of
presentationis takeninto account:It is mostsignificant
that no subject wasable to reconstruethefirst stimulus
presented, whichis, of course, the only one for which
they did not knowin advancethat there mightbe an
alternative interpretation. This striking relevanceof
stimulus order supports our conjecture concerningthe
effect of loss of naivete regardingthe task. Moreover,
stimuli werepresentedin order of decreasingsuitability
as confirmedby later experiments,andthis supportsour
explanation for the slight improvementin subjects’
successrate. Wecontrol for these confounding
factors in
the follow up experiments, but even without making
suchallowancesthe meansuccessrate overall wasstill
only 35 per cent. Typicalof the predicteddifficulty was
the reaction of subjects whenpressedto interpret their
rotated imageof the duckling: just as onewouldexpect
on a tacit knowledgeaccount according to whichthe
imageis intrinsically boundto its interpretation, many
subjects would volunteer the response that it is a
"ducklingon its back"!
Figure 2
The direct expectation of the pictorial medium
theoryis that the sameeffect shouldbe obtainableunder
imageryconditions. That is, if subjects are shownthe
figures in only one orientation, it wouldbe expected
that they could rotate their imageand discover the
alternative construal by inspection fromtheir rotated
image. Of course, the tacit knowledgealternative
account takes imagesto be abstract, intrinsically
interpreted conceptualizationsand wouldpredict that
such reinterpretation wouldbe difficult or impossible
for subjects to performin this wayon their rotated
images.
Figure 3
MethodWithout marking any distinction amongthe
stimulus figures, subjects were first shownseveral
distractors in the form of silhouettes of easily
recognizableanimalssuch as an elephant, ostrich and
marlin, none of which were orientation-dependent
15
The significance of ournegative results derives from
the fact that the mentalrotation and reinterpretation are
not only explicitly predicted by pictorial theorists, but
involve precisely the mental transformations which
have been classically taken as well established. Of
additional importanceis the fact that our task is readily
performedunder perceptual conditions, thereby entitling
us to expect it in imagery as well according to the
pictorial account. Further favouring reconstrual is the
fact that our figures are considerably simpler than the
representations of blocks stacked in three dimensions
employed by Shepard (1971) for which the mental
rotation has been claimed, and our own shapes are
geometrically no more complex that those of Cooper
(1975) for which complexity was specifically found not
to be a factor in the claimedease of rotation.
Even if the Finke et al. (1989) response
Chambersand Reisberg (1985) is not problematic in the
waysI have suggested (Slezak 1991), their "refutation"
is specific to the ambiguousstimuli and, therefore,
irrelevant to our entirely different imagery tasks. A
pattern of such failures on diverse perceptual phenomena
would leave only ad hoc ways of avoiding their
significance for the pictorial theory of imagery.
Therefore, as a follow-up, we have devised additional
experiments which attempt to reconstruct yet other
perceptual phenomenain imagery.
Expt. lb. Practice & Perception Effects
The ordering effect in the foregoing data in which
subjects showeda slight improvementfrom their initial
failure could be due to practice in the task rather than to
perceptual confounding as we had suggested. We
controlled for this possibility by giving each subject
prior practice with image rotation using Cooper’s
(1975) random polygon experiment.
At the same time, in order to preserve subjects’
naivete on all the stimulus figures, we altered the
previous instructions so that the imagery task would
not be knownuntil all the figures had been viewedand
memorizedin their initial orientation. Onceall stimuli
had been memorizedin this way subjects were prompted
by the brief flash of a figure on the screen, and askedif
they were able to recall the shape clearly. Only then
were subjects asked to rotate the shape 90 degrees
clockwise and asked whether they were able to find an
alternative interpretation.
Results: Significantly, prior practice with rotation of
images on the Cooper random polygons had no effect
on subjects’ performance and this possibility could,
therefore, be eliminated as a possible explanation for the
ordering effect in the preceding data. Indeed, despite
practice in rotating images,there was a dramatic drop in
the success rate as a consequenceof the newstrategy to
avoid perceptual confounding. Our data show only 8
successful reconstruals in 100 trials, and these were
almost entirely confined to two of the figures whose
shapes were said by subjects in debriefmgto be a "giveaway"due to certain telling clues.
Experiment lc.
Experiment 2. Figure-Ground
Reversal
The shapes illustrated in the left half of figure 4 are
such as to encourage perceptual organization into
several black objects which may, however, be reversed
to becomethe groundand thereby reveal the letters "EI".
Since the reversal in this form is somewhatdifficult to
achieve in perceptionitself, the effect can be elicited by
asking subjects to being the horizontal lines together to
touch the shapes as in the right hand figures, clearly
revealingthe letters.
Image quality.
It could be argued that under the new conditions for
avoidingperceptual reconstrual, the high failure rate was
now due to poor, inaccurate or otherwise degraded
images. In order to clarify the possible role of this
factor, we altered the conditions in such a way as to
maximizethe accuracy of encoded shapes in memory.
Subjects were tested on the imagery rotation task
nowonly after being permitted a very long (3 minute)
visual presentation of one of the stimuli (following the
usual distractors). During this extended viewing time,
subjects were encouraged to rememberdetails of the
single figure as accurately as possible. Whenthe
stimulus was removed, subjects were asked to draw it
from memoryin order to have some evidence of the
accuracy of the image. Subjects were then asked to
rotate and reinterpret it in imagination.In addition, D.F.
Marks (1973) VVIQ(Vividness of Visual Imagery
Questionnaire) was administered for further evidence of
image accuracy.
Figure 4
Despite the ease of the imagery task, not a single
subject in twenty trials was able to reconstrue their
imageto reveal the alternative construal as letters. This
was despite the fact that subjects’ subsequent drawings
of their memorizedimagewere highly accurate.
Results and Conclusion.: Despite high scores on
the VVIQaveraging 2.5, there were still only 2
successful reconstruals in 23 trials. Aboveall, the
accuracy of the drawings nowprovided fu’m grounds for
supposing that degraded image quality is not a likely
reason for the failure of imagereconstrual.
Expt. 3. Kanizsa Illusory
Contours
Stimuli of the sort illustrated in figure 5 were designed
to produce the familiar illusory contours, but were, of
course, not presented to subjects in this form, since the
16
effect wouldthen be created in perception.In order to
test the parallel with imagery,circumstancesmust be
contrivedwhichgeneratethe figure only in imagination
and, accordingly,the entire figure wasnot presentedat
once. Instead, the apical blackshapesweredesignedto
havegoodgestalt propertiesas figures andarc suchas to
discourageany inferences about other shapes of which
they mightbe a part. Theseshapes were presentedone
at a time for 30 secondsat their respectivepositionsand
then removedfrom view. Havingseen themonly one at
a time, subjects were instructed to imaginethemall
together and werethen askedwhetherthey wereable to
detect anyother emergent
shape,figure or object in their
reconstructed
image.
Figure 5
Results: Despite research on "creative mental
synthesis" whichsuggests that peoplecan use imagery
to mentallyassemblethe separatelypresentedparts of a
pattern (Finke 1990, p.21), only one subject out
thirty trials reported seeing a geometrical shape,
correctly identifying the emergentwhite figure. Again,
this overwhelming
difficulty with the task wasdespite
the fact that subjects’ drawingswerehighlyaccurateand
they werefrequently able to notice the emergentshape
fromtheir owndrawing.
Conclusion.
Notwithstandingthe claim by Finke et al. (1989)
have"refuted" Chambers
and Reisberg (1985), wehave
shownthat imagereconstrual is generally difficult or
impossibleto performunder conditions in whichone
wouldhaveexpectedit accordingto the pictorial theory.
Onthe other hand,however,these results are precisely
as one wouldexpect on the tacit knowledgeaccount
according to which imagery is highly abstract and
cognitive,and doesnot involveany internal, surrogate,
diagrammatic’objects’ to be apprehended
by the visual
system.
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