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  • 7/28/2019 articolo immagini mentali


    Percep tual and Motor Sk i l ls , 1966 , 23 , 101 1 -1 0 3 3 . @ Southern Universi t ies Press 1966Monograph Supplement 6 -V23FUNCTIONAL SIMILARITY OF IMAGING TO PERCEIVING:INDIVIDUAL DIFFERENCES I N V IVIDNESS OF IMAGERY1

    P E T E R W I N S T O N S H E E H A NUniversity of Sydney, Ausrralia2

    CONTENTS.........................xp. I. Behav ioral Correlates of Individu al Difference s in Ima ging - 1 0 1 5

    .......xp. 11. Analysis of Instrucdons 1 0 2 5Exp. 111. Vividness of Imagery as a Function of Familiarity with the StimulusImaged 1026..eferences 1032

    Summary.-Ss vary in the deg ree of vividness of their imagery. It is hy-pothesized chat different degrees of correspondence between imaging and per-ceptual beha vior are associated with ind ividual d ifferences in reported vividnessof imagery. Results sup po rt the hypothesis of a functional similaricy becweenimaging and perceiving. Vivid imagers behave in a way similar to the way theybehave when they perceive; poor imagers behave in both a s imilar and dis-similar fashion. Vivid imagery reinstimtes the accuracy of the perceiving proc-ess . Differences in experience with the object imaged d o not account for thevariation in vividness, although familiarity with the stimulus has some effecton the qualiry of imagery expressed. Fam iliariry with the object imaged ma kesfor more vivid imagery only in those Ss who have the capaci ty to image vividly.In recent years there has been an increased study of subjective phenomena.

    The advent of brain research, sleep studies, and research in sensory deprivation- -has draw n attention to the importance of hy pnagogic imagery, dream imagery,hallucinations, and the like. It is an important fact that individuals differ intheir capacity to image, but l i tt le is known a b o ~ ~ tow this cognitive ability

    - .functions and wh at are the mechanisms of its operation.Many imagery phenomena do not lend themselves readily to systematicstudy and control. Th e exp erim enter , studying the elusive nature of hypn agogicand dream imagery, can rarely utilize knowledg e of the experiences o n whichthey are based to draw inferences about them, and imaging Ss usually have dif-- -fering experiences with the objects they image. Ap peal can often only be madeto the veracity of Ss' introspections. Bu t if kno wled ge of past experie nce is avail-able, waking imagery can be stud ied mo re closely.

    The studies reported below attempt to control past experience and investi-'This smd y was conducted at the University of Sydney as pa rt of a doctoral pr og ram of re-search on visual imagery. I t was supported by US Publ ic Heal th Service N l M H Gr an tM 3950. T he au thor wishes to thank D r . J . P. Sutcliffe, Principal Investigator for theabove grant , for his help and assis tance throughout the work, and Mart in T. Orne, EmilyOrne, Ulric Neisser, and Frederick J. Evans for their helpful comments while the paper-was in preparat ion.W o w at Pennsylvania Hospiral, Th e Inst itute, Phi ladelphia, and U niversity of P ennsyl-vania.

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    1012 P. W. SHEEHANgate individual differences in reported vividness of waking, memory imagery.They are defined as objective investigations of imagery which examine the re-lationship between imaging and perceptual behavior and the nature of this rela-tionsh ip for different ratin gs of vividness of imagery.Methods of studying imagery can be divided into objective an d subjective,althou gh there is no sure criterion for distinguish ing between them. Disti nc-tions of this kind have been made by Angel1 (1 91 0) , Fernald (1 91 2) , andWoodworth ( 19 38 ). Com plete reliance on the veracity of introspection can bedistinguished from the correlation of an introspective report with objective orpublicly observable behavior. A study is considered objectiv e if i t correlatesvariations in Ss' introspective reporting with variations in their behavior whenimaging. A subjective study discusses only Ss' introspections about im aging.The distinction between the two types of studies can be applied more clearly tosome experiments than to others.An important subjective study of imagery was the early investigation ofBetts. Betts ( 19 09 ) studied imagery in seven sensory modalities by asking Ssto image to suggested items and found that few Ss lacked the ability to evokeimages when required. H e found marked individual differences in the degree ofclarity and vividness of Ss' imagery. Som e Ss had exceptionally vivid imagerywhile other Ss hardly any imagery at all. Betts' findings indicate that individualdifferences in reported vividness of imagery should be considered in imagery re-search. statements ab out what Ss do when they image should acknowledge thequality of the imagery expressed.

    The majority of studies which have correlated subjective reports of imagerywith experimental behavior have used problem-solving tasks to evoke imagery(Barratt, 195 3; Berg & Wo rchel, 1956; Fernald, 19 12 ). Results with these taskshave been disparate. Barratt (1 95 3) found that subjective report on the use andfacility of imagery was related to success on specific spatial tasks. Be rg andWorchel ( 19 5 6) , on the other hand, found great difficulty in setting up a pe r-formance task which indicated th e presence of imagery in its solution.

    There is no evidence that problem-solving tasks validly and reliably indi-cate the type and quality of imagery used in their solution. A mo re fruitfu lmethod of studying imagery is suggested by instructing Ss to image and thenrelating individual differences in introspective reporting to objectively measur-able features of Ss' imaging responses where the imaging behavor is defined byspecifying the relationship between imagery and past perception. N o imagerycan occur which is not composed of elem ents arising out of actua l perce ptual ex-perience of some kind. Images must depend on previous perception and thenature of this dependence is open to investigation.Th e correspondence between imaging and perceiving can be conceptualizedin a variety of ways. One way is to talk of th e functional similarity of imagingto perceiving. A n assertion of fun ctiona l similarity between the tw o processes

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    IMA GING A N D PERCEIVING: INDIVIDUAL DIFFERENCES 1013states only that a correspondence between sets of behavior exists, whatever thereason fo r tha t correspondence. T he notion of function stresses how an S be-haves when he images, as distinct from why he behaves. W he n an S images hecan behave in a variety of ways; he may describ e the stim ulus features of his sub-jective presenta tion, or construc t some copy of his image. Th ese sets of behaviorare behavioral products of th e process of im aging. Likewise, there are behaviora lproducts of the process of perceiving. A n S's imag ing behavior can be similar,or dissimilar to his perceptual behavior. A similarity between perceptual andimaging behavior demonstrates a functional correspondence between the twoprocesses.Investigators in the field of imagery historically have placed emphasis onthe stimulus accuracy of m ental imagery rather th an the depe ndence of imageryon previous perceptio n. Philoso phic thin kers in early sensationaliscic psychology(Titche ner, 1 919; W un dt , 1 91 8) stressed the view of images as copies of ea rlierimpressions or percep tions. They did not mak e clear wh at kind of copies theywere, although they strongly implied they were good ones.

    Current theorizing about imagery stresses a poor correspondence betweenimages and perceptions; images are characterized by inventiveness and originali-ty. Moore ( 19 19 ) talks of th e spontaneous and uncontro lled natu re of imagery.Hicks (1924) states that images are arbitrary and haphazard compared with theperceptions they depend on. McK ellar says that "visual images tend to be cre-ative rather than accurate in any photographic sense" (McKeUar, 1957, p. 2 3 ).Although the question of correspondence has not been studied explicitly, someinvestigations have cited relevant evidence (Bartle tt, 1932 ; Kuhlm ann, 1907;Zachariah, 1958).Imagers for Bartlett (1932) are people who confabulate; they add featuresthat are not in the original stimulus perceived or change features that are there.Bartlett used the method of Repeated Reproduction where Ss were given astory or a pic ture which they subsequently reproduced a numbe r of times. Al-though m ost confabulatio ns occurred in the late stages of reproduc tion, they wereofte n traced to the play of visual imagery. In the meth od of Desc ripti on Sswere told to examine stim ulus cards of h um an faces and were asked to describethem after a 30-min. rest interval. S with m ost importations was also the bestvisualizer; visualization was reported to favor the introduction of material fromextraneous sources.Kuhlmann's study indirectly referred a variety of recall responses to prop-erties of the perceived stimulus. Investiga ting memory consciousness, he askedSs to memorize a grou p of achromatic pictures for a fixed tim e period. Each Srecalled the piccures giv ing the orde r and nature of the imagery an d associations.Confabulation, denoted by the number of color, or motion responses in Ss'imagery, constituted 10% of the responses and were classified legitimately asoriginal responses.

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    1014 P. W. SHEEHAN

    These two investigations raise several methodological points relevant to theinvestigation of the functio nal correspondence between imagin g and perceiving.

    First, Ss' perceptions should be indicated precisely. Th e lack of d efinitio nof perception in Kuhlmann's study prevented a valid examination of originalresponses other than color and motion. Unless perceptions are defined in thefirs t instance, no legitimate statem ent of compa rison of imagery w ith perceivedstimuli can be made . Specification of perception is highly relevant to the anal-ysis of memory responses. For example, no valid inferen ce about the accuracyof imagery can be offered without knowledge of whether Ss misperceived anyparts of the stimulus on inspection.

    Second, the studies of Bartlett and Kuhlrnann employed instructions to re-call and discussed the nature of imagery fro m the results. Ye t inferences abou tthe function of imagery should consider the possible behavioral differences be-tween Ss asked to recall and Ss explicitly asked to image. Th e performance ofthose whose recall does not primarily depend on imagery may vary from theperformanc e of those Ss whose recall depend s heavily on imagery.Th ird , the quality of imagery should be indicated. Since Ss differ in theirreports of the vividness of their imagery, it is important to determine whetherdifferences in subjective experience are related to differences in behavioral cor-respondence. It is legitimate to ask wheth er the behavioral correspondence be-tween the two processes is closer, when Ss image mo re vividly. If diffe rentstatements about th e vividness of imagery are associated with differe nt behav ioralcorrespondences between imaging and perceiving, then vividness reports can beindexed objectively by reference to behavior and mad e mean ingful.Finally, a study of imagery should consider Ss' differin g expe riences with theimaged object. If varia tion in vividness of imag ery is acco unte d for entirely bydifferences in familiarity with the stimulus imaged, then any statem ent of rela-tionship of vividness to behavioral correspondence becomes indeterminant. Thereis scant evidence in the lite rature which bears directly on the issue of familiarityand vividness of imagery. In the studies carried out by K uh lm an n and BartlettSs were given practice in making a series of reproductions relating to a givenevent, but familiarity was not varied by repea ting experience with the eve nt itself.

    Th e above com men ts indicate the need for careful definition of im agingand perception behavior. Conclusions about the accuracy of imagery should bebased on close analysis of both recall and initial perceptions. Th ere should bealso some regard to variations in introspective reports and the changes in be-havior which accompany them. Th e following investigations aim to considerthese criticisms. They atte mp t to define imaging and perceptual behavior sothat the correspondence between them can be determined. A preliminary studyby the author analyzed the verbal recall of picture material following the meth-ods of reproduction reported by Bartlett (1932). Results highlighted some ofthe methodological problems raised in discussion above.

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    T he s n ~ d y imed to examine the relationship between de scriptions of stimu-li when perceived and descriptions of the same stimuli when subsequently im -aged, and the nat ure of the relationship between degrees of such correspon denceand the ratings of vividness given to images of th e stimuli. Eig ht Ss describedsix pictorial scenes varying in stimulus complexity which were presented for p er-ception by slide projection . Ss later imaged the stimuli, described the ir images,and indicated the vividness of their imagery on a 7-point rating scale. Individu aldifferences in vividness ratings bore no consistent relationship with degrees ofcorrespondence between image and perce ption descriptions. Stimulus elementscom mo n to both desc riptions were associated wit h imagery of va rying vividness,and vivid ratings accompanied both positive and negative correlations of theserial orders of occurrence of the elements common to the two descriptions.

    Results were taken neither to confirm nor refute the hypothesis of a rela-tionship between vividness of imagery and a correspondence between imagingand perceiving, since S's initial perceptions of the stim ulu s were de fined inade-quately. N o S reported the same number of s t i m u l~ ~ slements in his descriptionof any given stimulus presented for inspection. Th e method of description failedto ensure that all elements actually perceived were indicated to E, and it did notidentify misperception of elements in the complex stimuli. Am biguity in theinterpretation of the meaning of Ss' perceptual descriptions obscured the defini-tion of imaging responses and their relationship to perception.

    Th e following series of ex periments a ttemp ted more systematic control overthe processes of imaging and perceiving so that the behavioral correspondencebetw een them could be exam ined and related to vividness of imagery. They alsoexamined the behavioral differences between Ss asked to recall and Ss asked ex-plicitly to image, and Ss' readiness to vary their ratin gs of vividness of im agery.In summary, Exp. I studied the form of S's behavior when an image of a par-ticular vividness was reported and the differences in behavior under instructionsto image and recall; Exp. I1 attempted to validate results of the first study by in-vestigating some demand characteristics implicit in the instructions to Ss; andExp. I1 1 concerned the effect of stimul~~samiliarity on the vividness of imageryreported.


    Th is study related behavior in an imagery and recall situation with behaviorin a perceptual situation. T he behavior was the manipu lation of blocks.

    T he stimuli were geometrical figures reproducible by com bining blocks intopatterns. Ss construc ted the inspection stimulus by means of th e blocks provided.The same set of blocks was used when Ss were asked to perceive, image, or re-call the stimulus they had just seen.

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    1016 P.W. SHEEHANThis approach minimized the occurrence of illusion since the geometrical

    elements of the percepcual stimuli were clearly definable. Ss were forced to per-ceive the elements of the design correctly in order to reproduce the design withthe blocks during perception. T he contrived absence of illusion eliminaced therecollection, forge ttin g, or reminiscence of illusory ma terial i n the recall stage.Th e possibilities of Ss recalling correctly perceived m aterial they did not r epo rt(rem inisce nce) and of recalling st imu lus elements no t actually perceived werealso eliminated, because Ss were m ade t o indicate each of the stimulus elem ents inthe experimental display. Assuming that a non-perceived element would no tbe indicated in the perceptual response, the procedure isolated three sets of ele-me nts for close study: the set of elem ents correctly perceived and indicated inboth the perceptual and memory response (recollection) ; he set of elemen ts cor-rectly perceived and indicated in the perceptual response but not indicated in thememory response (forgetting) ; and confabulation. Since perceptual elementswere fixed, confabulation was defined as the occurrence of an element, which Sdid not perceive in constructing the stimulus but which was contained in hisreproduction from memory; it was the occurrence of a new element in reproduc-tion from memory which was not contained in the perceived stimulus.

    The standardization of the stimulus situation and the way one perceives itminimizes irrelevant individual differences, but some variation in imaging be-havior is needed to study the beha vioral correlates of individ ual differen ces invividness of imagery. If such differences do occur, the following expe rime ntoffers an expe rime ntal test of the relationship of vividness ratings t o variation incorrespondence between ima ging and perceptual behavior. Particular attentionis paid to the hypothesis that imaging is characterized by confabulation, in orderto test the creativity notions of imagery (Ba rtlett, 1 932; McK ellar, 19 57 ).Materials and Affaratus

    Several displays were selected as inspection figures. Tw elve judges p re-viously rated these as show ing some pattern in their arra ngem ent of shapes andcolors. Stim uli are show n in Fig. 1.All stim uli used four distinct geometric forms: triangle, circle, square, anddiamond. A geometric form of a particular color was never duplicated i n anydesign and different sets of colors were used with each display to emphasize dif-ferences among the three experimental patterns.Color transparencies were prepared for projection of either the display as awhole or any one elemen t of it. Slides of in dividu al elemen ts of displays showedthe geomecric element in correct spatial position relative t o th e ocher elements inthe display. Th e dimensions on the slide were such that a t a distance of 10 ft .from the screen a circle, diameter 3.5 in., was flashed onto the screen.

    S could duplicate each design by selecting colored geome tric forms from fourpiles of blocks placed on a small table in fro nt of him . Four sets of eig ht Ma tteblack painted wooden cubes, 1 in. on a side, were used to represent sets of tri-

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    PRACTICE R B Y0 0O n 0 Y R G0 0 0 G R B

    I O n 0 Y G Bo n 0 G Y Ro n 0 R E G

    II 0 0 0 0 R Y G BO n n O B R Y G0 0 0 0 G B R Y

    I1 1 G Y B Rn o 0 n0 0 0 0 B G R Y0 0 0 0 R B Y G

    Y R G Bno 0 nFIG. 1. Stimulus display patterns

    angles, squares, circles, and diam onds. Each block showed a particular geometricform in four different colors: red, green, yellow, and blue. Eigh t blocks ex-hibited only triangles, e ight blocks only circles, and so on, and there was a differ-en t color o n each of four faces of each block.

    S sat in an experimental room blacked out except for lamp illumination ofthe blocks. Th e physical image on the screen fell ahead and slightly to th e rightof S s line of vision. A 35-mm. slide projector was used with an interval timerand variable transformer. Instructions were delivered by a tape recorder.

    The Koh s Block Design Test (K ohs, 1927) was used to familiarize Ss withpattern construction and to provide a control task for the interval between per-ception and imaging, or recall.

    A shortened fo rm of Betts' Questionnaire Upo n Me ntal Imagery (Betts,1909) assessed individ ual differenc es in rated vividness of im agery am ong Ss.This scale will subsequently be referred to as the Betts QMI.3 The Betts ratingT h e Betts QMI contains 35 items of the original Betts questionnaire (Bects, 1 9 0 9 ) . Fiveitems wrtain to each of seven sensorv modalities: thev are visual. auditorv. cutaneous.kinaesbetic, gustatory, olfactory, and o&anic. In ;he vkual (audit&) mo d~lity , .g., ~s

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    1018 P. W. S H E E H A Nscale (Betts, 1909) was used to record the vividness rating for imaging ofstimuli. Th e scale ranged from a score of 7 (n o image present at all) , through5 (vague and dim) to a score of 1 (perfectly clear and vivid).Sab ects

    Thirty eight male and 47 female Ss were drawn as volunteers from under-graduate classes in psychology at the University of Sydney. Six independentgrou ps of Ss were used; these groups are as set out below. Before the m ain ex-periment Ss were each given the Betts QMI and the six groups were equated withrespect to the total and the visual scores on the test. Unev en numb ers of Ss werein the groups owing to the difficulty of m atching groups on b oth imagery scores.E did not know the Betts scores until the experiment was near completion for the85 Ss; then comparable groups were drawn up.Procedure

    The experiment examined the effect of different instructions, specificallyto "image" and to "recall." A control con dition was introduced wh ere S wasgiven instructions to perceive the scimulus display for the second time. Af terthe stimulus display was perceived twice Ss in the control condition were askedto image the pattern they had just perceived. Imag ing after two perceptions,rather than one, provided a study of the effect of added exp erience on ratings ofvividness of imagery. T he contra st in thi s set of cond itions specifies instructio nsto "image" versus "recall" versus "re-image" (im ag ing after tw o perceptions ofthe stimulus ) and will be referred to as Con dition s of Reproduction .

    T w o conditions were introdu ced to study the effect of prior presentation ofelements of th e display, Prior Analysis and N o Prior Analysis. In the condicion ofN o Prior Analysis the whole display was presented, at once, for perception. Inthe condicion of Prior Analysis S was presented with each of the individual ele-ments of a display one at a time in a fixed serial order, before presentation ofthe whole pattern.

    In summary, six conditions arose from combination of Image, Recall, Re-image and Prior Analysis, N o Prior Analysis. Ss indicated perception of the dis-play by constructing it with blocks und er either Prior Analysis or N o Prior Anal-ysis instructions. They then re-constructed the pattern un der Image, Recall, orRe-image instructions.

    For all conditions of p erception the whole display remained on the screenwhile S was constructing the pattern. Th e projector was switched off wh ile Sconstructed the blocks under recall or image instructions. Individual elemen tsare asked to th ink of seeing (hea r ing ) " the sun as i t is s inki ng below th e horizon" ("thewhist le of a locomotive") and to consider carefully the image which comes to their mind'seye (e ar ). Extensive psychometric analysis of the scale (She ehan, 1965) has indicatedthat a single factor accounts for a considerable part of the variance of test scores, with alli tems loading highly on the main component . Th e scale has been cross-val idated on anindependent sample.

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    I M A G I N G A N D P E R C E I V IN G : I N D I V I D U A L D IF F E RE N C E S 1019of the display were presented for 0.5 sec. All images, both elemen ts and totaldisplay, were projected o nto the screen at a d im, si~ prathre shold evel of illumina-tion. Ss were first shown the practice display and then the three expe rime ntalst im ul i, th e ord ers of pre sentati on be in g 1-11-111, 111-1-11, and 11-111-1. A givenorder was allocated at random to a given S.

    T he sequence of ev ents for each S was: S tested on Be tts QMI; S tested onKohs block test; S constr~lcted attern on screen under perception instructions; Sagain worked at Kohs test for 40 sec. and then reconstructed patte rn u nder ap-propriate experimental instructions. W her e S had received image instructions avividness rating was obtained. S worked at the Kohs block test for 2 min. be-fore the next display was flashed onto the screen.

    Instructions to groups are reported below.General.-"Familiarize yourself with these blocks. There are four different sets-

    triangles, circles, squares, and diamonds. Th ere are four differe nt colors-red, green , yel-low, and b l u e - o n each block in each se t. "Prio r analysis.--"I am go ing to present a series of figures on th e screen in fr on t of you.Wa tch carefully what comes onto the screen."( E presented elements separately, then total pattern.) "Now I want you to indicateto me the pattern of the piccure on the screen. You are to indicate the pattern by meansof the blocks. Put the blocks together according to the pattern o n the screen. Each blockrepresents a un it of the design, and if p ut together in a certain way they w il l mak e u p thedesign on the screen. Th e separate units making u p the design have just been shown toyou one at a t ime. No w pu t the blocks together in accordance with your perception of thepatterning of the image on the screen."

    No pri or analysis.-"I am goin g to present a figure on the screen in fron t of you.Watch carefully what comes onto the screen . . . ( instructions continue as for Pr ior Anal -ysis insrructions om itti ng reference to prior presentation of uni ts) . . . of the patterningof the image on the screen."

    When Ss had constructed a pattern with the blocks to duplicate the patternon the screen, E switched off the projector and directed them to work on theKohs block tasks while he set up the apparatus for the next stage.

    Image.-"Now I w a nt you t o c al l to mind a nd r et ain a n i m a g e a me n ta l p ic tu re i ny ou r m in d's ey-f [ he d es ig n yo u sa w o n t h e sc re en a m i n u te a go . I want you to evokea mental piccure of the composite figure. When you have this mental picmre in yourmind's eye, I want you to indicate to me th e pattern of this picture by mean s of theblocks provided. Be sure to work with the mental picture in your mind's eye. Con-struct the pattern of your mental picture and nothing else. Rate the vividness of yourimage. If you have n o mental picture, then m ark 7 on the scale in f ront of you. T ryto evoke some image of the design, and try to reconstruct its pattern with the blocks."

    Recall.-"Now I wa nt you to recall the patte rn of the design you saw on th e screena minu te ago. Try to remember wha t the composite f igure was l ike and reconstruct thepattern with the blocks provided. D o not try to evoke any men tal image or picture ofthe pattern. Just indicate to m e wh at you remem ber of it."Control.-Perception instructions were given a second time after a 40-sec. rime in-terval f rom the f irst reproduction under perception instructions. After an interval of 40sec. S eceived image instructions, as above.

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    MeasuresSeveral categories were used for scoring Ss' responses.Original resp on ses.X on side ring a colored geometric form as an element of

    a display, this measure was the numb er of times S used blocks in h is image orrecall construction which he did not use in his perception construction.Erro rs of location.-These were the numb er of elem ents of a display in the

    image, or recall reproduction which were not in the same position in the stim-ulus patte rn as wh en correctly perceived. Th is measure involves forge tting andconfabulation. Forgetting refers to the elements which are contained in thestimulus and in the reproduction from memory but are mislocated in the latter.The remaining elements comprise the category of response, confabulation.

    I?zversions of order.-The stimu lus display can be considered as a pe rm uta -tion of some arbitrary ordering of elements, or may depict an order of elementswhich is determined experime ntally. Consider for exam ple the orde ring ofblocks in a matrix given by rows and columns from top left to bottom right.Other patterns made up of the same color-form elements may be considered tobe permu tations obtainable from the ordering. Th e "distance" of any permu ta-tions from this ordering can be measured by counting the number of pairwiseinversions of order needed to transform the permutation into the given order.Th is score is nor unambigu ous since the same num ber of inversions may be re-quired to transform quite different perm utations into the same order. Neverthe-less, small numbers of inversions indicate that a pattern is quite like the refer-ent while large numbers of inversions indicate that a pattern is quite different.

    Vividn ess ratings.-Ratings indic ated by S after he imaged each desig n, an dgiven to items on the Betts QMI were also analyzed.Results

    Since image ins tr~ ~c t ion so not app ly to Ss lacking imagery, results w ere ex-cluded for Ss giving vividness ratings of 7. Two Ss given image instructionsused more blocks in their memorial reconstructions than they used in their per-ceptual constructions. Their performance indicated confabulation which madecalculation of errors of location and inversions invalid. Con sequently, where thenumber of memorial elements exceeded the number of perceptual elements forthese two Ss, their results were included in analyses of original responses burexcluded fro m conside ration of errors of location and inversion^.^Analysis of original responses.Xonfabulation rarely occurred with stimu-lus 111. For stimuli I and I1 the presence-absence dichotomy yielded most in-formation. Frequencies of original responses for the separate experimental con-ditions are set O L I ~n Table 1.Two multiple contingency analyses (Sutcliffe, 1957) were carried out on'Resul ts for one S were in the Prior Analysis condit ion for s t imulus 11, and for the o therS were in the N o Prioc Analysis condit ion for s t imuli I and 11.

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    OF STIMULI AND 11Stimulus Prior Analysis Condition of ReproductionImage Recall Re-image

    E E' E E' E E'I Prior Analysis 5 10 7 6 6 7No Prior Analysis 10 3 14 2 8 5I1 Prior Analysis 6 9 8 5 5 5No Prior Analysis 10 4 14 2 9 4

    frequency data for stimuli I and 11. Th e three classifications were: condition ofreproduction (image, recall, and re-im age ), prior analysis (present, ab sen t), andconfabulation (present, absent). Parameters were estimated from the data.Th e following findin gs were evident. Th ere was a significant interaction be-tween prior analysis and confabulation indicating that additional experiencelowered the incidence of original responses (fo r stimuli I and 11, respectively,x2 = 9 . 1 7 , d f = 1 , p < . 01 ; an dx S= 6.16,df = 1 , p < .02 ). Ss in there callcondition behaved differently from Ss in the two imaging conditions. Th e in-cidence of confabulacion for the three conditions of reproduction are set out inTable 2.

    TABLE 2

    Stimulus Confabulation C o n d l u o n of ReproductionImage Recall Re-imageI Error 15 2 1 14No Error 13 8 12I1 Error 16 2 2 14No Error 13 7 9

    The high incidence of confabulation for the recall Ss indicated that a poorcorrespondence between perceptual and memorial behavior is more characteristicof recall than it is of imaging.Analysis of errors of location.-Error scores were correlated with vividnessratings given by Ss to images of th e display pattern s. Ove r all imag e cond itionsfor stimuli I , 11, and I11 the product-m om ent correlations of error-of-locationscores with vividness ratings were 0.61, 0.60, and 0.51, respectively. Th e re-gression, however, was non-linear. Ss who said they imaged vividly tended t omake few er errors than Ss who said they imaged poorly. But scores of Ss imag-ing poorly ranged from few to many errors.

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    MEANERROR F LOCATION IN ~ M O R I A L EPRODUCTION OF STIMULUSPAITERNS , 11, AND 111Stimulus Prior Analysis Condition of ReproductionImage Recall Re-image

    I Prior Analysis 2.00 3.08 3.15No Prior Analysis 5.33 4.37 3.92I1 Prior Analysis 4.36 5.67 6.50No Prior Analysis 7 .OO 6.50 5.15111 Prior Analysis 11.27 9.54 9.27No Prior Analysis 12.77 10.50 8.75

    The mean error-of-location scores for the conditions of reproduction andprior analysis are reported for the three stimulus display patterns in Table 3.Mu ltiple contingency analyses were carried out o n frequencies of Ss scar-ing above or below the median error score calculated over all experimental con-ditions. T he three classifications for the analyses were: con diti on of reproduc-tion (image, recall, and re-image), prior analysis (present, absent), and error(present, abs en t). Parameters were estimated from the data and analyses 'werecarried out separately for each of the three display patterns . For stimu lus I therewas a significant interaction between prior analysis conditions and error ( x 2=7.14, df = 1 , p < O l) , which indicated that added experience w ith elem ents ofthe display pattern mad e for less error in memorial reproduction. Th er e wassome tendency for recall behavior to be differentiated from imaging behavior.Error scores above the median occurred in 62% of Ss in the recall conditio n com-pared with 48% and 42%, respectively, for Ss in the image and re-image groups.Analysis of inversion scores.Scores were calculated by counting the num-ber of pairwise inversions of orde r needed t o transform S s ordering of eleme ntsin his pattern construction to the ordering of elements which S gave in per-ception. Th e order chosen for each S was determined experimentally and wasthe ordering of blocks S gave in his perceptual conscruction. W he re om issionsoccurred, and there were em pty cells in the pa ttern constructions, inversion scoreswere calculated by randomly allocating num bers to the empty cells. For thecontrol conditions scores were based on the two perceptual constructions only,-so data provided examination of behavioral differences involved in imaging, re-calling, and re-perceiving.

    There was marked heterogeneity of variance of inversion scores in the ex-perimental subgroups; the variance of scores in the control groups was verymuch smaller than in the image and recall groups. Six analyses were carried outby the Kruskal-Wallis rank method (Siegel, 19 56 ). Differences am ong thethree reproduction groups were investigated separately for each of the prioranalysis and stimulus conditions. Table 4 contains the mean rank scores for

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    Prior Stimulus I Stimulus I1 Stimulus 111Analysis Image Re- Con- Image Re- Con- Image Re- Con-call trol call trol call trolPresent 22.93 29.62 10.15 22.86 22.77 8.70 22.67 23.00 12.82

    ( P< 001 ) ( P< 0 1 ) ( P < 05)Absent 25.04 24. 69 12.73 17.65 30.22 14.62 23.93 20.97 19.38

    (P < 02) (P < 01) (P > 05 )the experimental groups and lists the probabilities associated with the tests ofsignificance.

    Results indicated that imaging and recall behavior were distinct from per-ceptions. W he re there were appreciable differences between image and recallgroups, imaging was closer to re-perceiving than recall.Analysis of vivtdness ratings.-Table 5 sets ou t the mean vividness rati ngsfor the prior analysis conditions and two conditions of reproduction (ima ge, re-ima ge). Ss giving a rating of 7 to any of the three stimulus patterns were ex-cluded from the results.


    I Prior Analysis 3.33 3.33No Prior Analysis 4.69 3.58I1 Prior Analysis 4.00 3.78No Prior Analysis 4.77 3.50I11 Prior Analysis 4.67 4.00No Prior Analysis 4.15 3.83

    Tests of significance of the differences between means set out in Table 5were made by Lindquist's Type I11 model (Lindquist, 1953) of analysis of vari-ance, and yielded the following findings. Th e re-image grou p gave more vividimages than the image group ( F = 6.09, df = 1 / 3 2 , $ < .02), and images tomore complex stimuli were rated as less vivid (F= 3.34, df = 2/64, $ < .05).T he effect of pri or analysis on vividness of imagery was depen den t o n the com -plexity of the stimulus presented; imagery was more vivid for Prior Analysisthan for N o Prior Analysis when images were given to the less complex stimu li( F = 5.60, df = 2/64, $ < .01).

    Product-moment correlations were calculated to examine the relationship

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    P. W. S H E E H A NTABLE G


    Betts Score Prio r Analysis Co nd ~r lon of ReproductionI m a g e Re-image

    Visual Prio r Analysis .3 1 .43N o Prior Analysis .45 .57

    All Items Prior Analysis .14 .45N o Prior Analysis .52 . 3 7

    between visual and total Betts QMI scores and the vividness ratings given toimages of experim ental stimuli. Experimental ratings were summ ed over allthree display patterns. Correlation s are listed in Tab le 6. Some tendency maybe seen for the correlation between Betts QMI scores and ex perim ental ratings toincrease as experience is increased by repeated presentation of the stimulus, be-fore imaging.Discussion

    Results show many soiuces of discrepancy between perceptual and mem-orial accounts: individual differences in imag ing capacity, stimulu s complexity,familiarity with th e stimulus, and the n anir e of the task itself.

    Vivid im agers accurately reprodu ced the stimulus as they perceived it. T heclose correspondence between imaging and perceptual behavior for these Ss doesnot support the notion that vivid imagers are characteristic confabulators andinventors. Previous studies generally have failed to specify individual differencesin vividness ratings, but rep orts of inventivene ss in imagery a re usually m ea nt todenote good imagers rather than poor ones. Th e present finding s indicate that,when individual differences in vividness are considered, errors of reproductionactually accompany poor imagery and not vivid imagery.There were more original responses and more inversions for recall than forimag ing instructions. Confabulation accompanied recall rather than image in-structions; and when confabulation did occur in imagery, it tended to accompanypoor rathe r than vivid imagery. Since Ss in the image and recall group s wereequated with respect to their capacity to image, it appears that confabulation ismore characteristic of recall than it is of imaging regardless of Ss' capacities toimage.Original responses were given more often to stimuli I and I1 than to stimu-lus 111. This evidence suggests that confabulation should be considered both asa stimulus and a subject variable, since some stimuli favor original response morethan others.There were fewer inversion scores for the control condition than for thememorial conditions; this indicated some reliability for the inversion measure

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    IMAG ING A N D PERCEIVING: IND IVID UAL DIFFERENCES 1025since one would expect behavior while perceiving for the second time to becloser to the original perceptual behavior than behavior while imaging or recall-ing. W he re there were appreciable differences in inversion scores for recall andimage groups, imagery behavior was closer to behavior d uri ng re-perce ption thanbehavior dur ing recall. Th is findin g also conflicts with theorizing about imagerybeing divorced from the constraints of the perceived stimulus. Ima ging Sstended to behave more as they did when they were perceiving than did Ss whowere asked to recall.

    Since the products of imaging differ from the products of recall, it is im-portant to ask whether the increased accuracy for imaging relates to a differentdefin iton of the reproductive task employed. Image instructions referred to thephras e "menta l picture " which im plies the notion of "clarity of detail" an d per-haps accuracy. Th is implication would not be present in the recall instructionswhe re Ss were asked not to image. Furth erm ore, if im aging is not subject tovoluntary control, the instructions for recall would cause some difficulty for Sswho were vivid imagers.

    The following experiment provides a check needed for the instructions torecall and image. It examines some of the demand characteristics (O rn e, 195 9)implicit in the experim ental instructions to Ss, and the issue of restraint o n imag-ing. Tw o variations in recall instructions were used. Th e first variation em-phasized accuracy in reproduction. Th e second variation deleted th e reference toSs "trying not to image" and emphasized recall alone.5

    EXP. 11: ANALYSISOF INSTRUCTIONSThis study is reported in summary form below, but in detail e1sewhere.O

    Tw enty-tw o male and 18 female volunteers from undergraduate classes in psy-chology at the University of Sydney served as Ss. Th ree inde pend ent gro ups of10 Ss were equated with respect to Betts QMI mean scores, visual and total. On egroup was given standard image inscructions; the second group was given recallinstructions with stress on accuracy; and the third group was given recall in-structions with no constraint on imaging. Stimuli I and I1 (Fig. 1) were pre-sented to Ss for inspection, and Ss constructed blocks to indicate perception andrecall, as in the previous study. T he order of presentation of the stimu li wasalternated f or successive Ss. Analysis of errors of lo cation, orig ina l responses,and inversion scores showed significant differences among instructional groups.The trend for all measures was toward accurate performance for the imaginggrou p. Reproductions u nder recall instructions were less accurate than those un-der image instructions despite the emphasis on accuracy and lack of constraint onVarying instructions ha been shown previously to be an effective method for examiningthe expectations Ss have about what E wants (Singer & Sheehan, 1965) ."Full description of this ex perimen t and discussion of its results are reported with theAmerican Documentation Institute, Auxiliary Publications Project, Photoduplication Serv-ice, Library of Congress, Wash ington , D . C. 20 540 . Order Document N o . 9111, remitting$1. 25 for 35-mm. microfilm or 6- by 8- in. photocopies.

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    1026 P. W. SHEEHAN

    imaging. Results replicated th e findings of the previous study and allow one toset aside the possibility tha t they were artifacts of the instructio ns used.

    Exp. I indicated the importance of familiarity as a factor affecting imagery.Results indicated that prior analysis of the st i m ~ ~ l u sade for a decrease in vivid-ness ratings (im ply ing mo re vivid imagery) for the less complex stimuli. W he reSs had two perceptual experiences with the display pattern before imaging it,images were rated as more vivid than otherw ise. Also, the relationship betw eenBetts QM I scores and experimental ratings was more obvious as experience in-creased through repeated presentation of the perceived stimulus before imaging.(One can reasonably assume that Ss imaging items in the Betts test are familiarwi th wha t they image, since items relate to aspects of everyday expe rience.) Ifthe experimental task is considered a learning task, more accurate reproductionswould accompany increased familiarity with the stimulus. It remains to be seen,however, whether ratings of vividness of imagery are subject to change throughexperience with the stimulus imaged. It may be that individu al differences invividness of imagery are entirely accounted for by differences in familiarity withthe stimulus.

    The following experiment permitted study of the range of alteration ofvividness ratings and the association of this change with variations in a mounts ofexperience with the object imaged.

    Exp. I reporte d inter-ind ividu al variatio n; the present study considered in-tra-individual variation in vividness ratings. It was an investigation of the rela-tionsh ip of familiarity, throu gh repeated exp erience with a stimulus, to ratings ofvividness of imagery of the familiar object.Method

    The materials and apparatus were those described in Exp. I.Two senior psychology students and 14 graduates at the University ofSydney served as volun teer Ss. Th er e were 9 females and 7 males. N o S hadany previous experience with experiments of this kind.

    Each S was given the Betts QMI at the start of the experiment. S was askedto reconstruct a practice stimulus (Fig. 1) under N o Prior Analysis instructions.Ss then reconstructed this pattern under image instructions following Kohsblock construction. Th is phase was taken as sufficient to familiarize Ss with theexperimental procedure.

    Stim uli I, 11, and I11 were pres ented , one s tim ulu s on each of three successivedays according to varied orders set out in the procedure for Exp. I. In each ex-perim ental session Ss were given 10 trials with a particular stimu lus. A trial con-sisted of th e following sequenc e: stimulus reproduction under N o Prior Analysisinstructions for perception, Kohs block construction for 40 sec., pattern con-

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    struction under image instructions and vividness report; Kohs block constructionfor 60 sec. Between trials S was denied the op po rn ~n ity or inspection of thepattern which he had just constructed. A limit of 10 trials was set in anticipa-tion that after such experience the stimulus would be thoroughly learned andfamiliar.Resuks

    Errors of location, original responses, and vividness ratings were recorded.Grap hical represe ntation best illustrated the pat tern of results. Plots of

    errors of location and imagery ratings against trials showed marked individualdifferences. Ratings for some Ss rose from low to high over trials, while f orother Ss ratings rose little, if at all. An in depe nde nt metho d of classification foraveraging curves over Ss was provided by the Betts QMI visual score. Ratin gsof "3" (moderately clear and vivid) and "4" (not clear and vivid, but recogniz-able) were used to differentiate good imagers from poor imagers on any givenitem. Mean ratings partitioned Ss into two groups: 10Ss showing vivid imageryan d 6 Ss showing poor imagery. W ith in each group Ss exhibited th e patternshown by the means described below. On e exception was foun d amo ng the vividimagers and his results are described separately.

    Mean curves are given respectively in Fig. 2 for those groups with vividimagery and with poor imagery for each of the stimulus patterns. M ean errorsof reproduction are plotted against trial number. O n the same gra ph are plottedthe mean vividness ratings from trial to trial.

    Table 7 shows the frequency of occurrence of errors accompanying vividand non-vivid ratings for the three experim ental stimuli for the 15 Ss whoseresults are graph ed above. Results of Ss giv ing a rati ng of 7 on one or moreof the trials for a particular stimulus were excluded from consideration of theresults for that stimulus. Ss giv ing ratings of 7 were included in the graphsabove, since it was possible for Ss givin g a rating of 7 on o ne trial to change thatrating on another trial.

    The results of the previous studies again were replicated. Table 7 showsthat, by comparison with poor imagery, vivid imagery was accompanied by fewererrors of location and fewer original responses. Th ere was also an expected de-crease in the incidence of error with increase in the number of practice trials.Discussion

    I t is apparent from examination of the figure that repeated stimulus presen-tation over trials led to reduction in error. Th e effect of p ractice on erro r scoreswas mu ch the same for the two imagery groups, but the effect of familiarity withthe stimulus on the performance of the two imagery group s was markedly differ-ent. As familiaricy increased through repeated presentation of the stimulus, Sscharacterized as vivid imagers on the Betts QMl altered their ratings toward themo re vivid. Ra ting s given by Ss characterized by the Betts Q M I as poor imagers

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    1028 P.W. SHEEHANremained poor and their results appeared to be independent of familiarity withthe stimulus. Th is trend was app aren t regardless of the com plexity of the stimu-lus. Th ere was only one exception to this result. O ne S, a vivid imager, did notchang e his ratings over trials. Th e main observation was a marked interaction


    1 --RATINGS- - - - - - _ _ _ _ -0 1 2 3 4 5 6 7 8 9 1 0TRIALS


    ----..--- RRORS- -- PATINGS0 0 1 2 3 4 5 6 7 8 9 1 0TRLRLS



    0 1 2 3 4 5 6 7 8 9 1 0 0 1 2 3 4 5 6 7 0 9 1 0TRIALS TRIALS

    la) W D MRGERSE R


    I2 I- - _ _ _ _ _ _ _ _ - - - - - ------ RRORS6 5 ----RATINGS

    10 0 1 2 3 4 5 6 7 8 9 1 0TRLRLS

    FIG. . Mea n error of reproduction a nd vividness rat ing for good and poo r imagerson ind iv idual t r ia l s with s t imul i I ( t o p ) , I1 ( c e n t e r ) , a n d 111 ( b o t t o m )between the kind of S a person is with respect to his imagery and the effect offamiliarity upon vividness ratings.Table 7 highlights an im po rtan t feature of performance of Ss wh o gavelow ratings. Confabulation was associated with poor imagery. Ove r all stimulithere were 58 instances of confabulation in the 10 practice trials; and 52 of theseaccompanied poor vividness ratings. Absence of orig inal responses was associated

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    FOR STIMULI, 11, AND 111Rating Trial Stimulus I Stimulus I1 Stimulus 111Location Confab- Location Confab- Location Confab-Error ulation Error ulation Error ulation

    V i v i d * 1 1 0 0 0 3 12 0 0 2 1 2 13 0 0 1 1 2 04 1 1 0 0 3 05 0 0 0 0 1 06 0 0 0 0 0 07 1 0 0 0 0 08 0 0 0 0 0 09 1 1 0 0 0 010 0 0 0 0 1 0

    Not Vivid 1 11 8 10 9 8 42 7 5 5 5 7 33 5 3 3 3 6 14 1 0 2 2 4 05 0 0 2 2 3 06 0 0 2 2 2 17 0 0 1 1 1 08 0 0 1 1 1 09 0 0 1 1 1 1

    10 0 0 1 0 1 0"Vivid rating = 1,2, 3; not vivid, rating of 4, 5 , 6.with vivid imagery rather than poor imagery. Confabulation did not characterizethe imagery of the vivid imagers wh o showed errors in the ir imagery construc-tions.

    CONCLUSIONThe similarity between perceptual and imaging behavior indicates a func-

    tional correspondence between imagin g and perceiving. Indiv idua l differencesin imaging are related to individual differences in correspondence between thetwo sets of behavior. T he relation ship betw een vividness of imagery and cor-respondence in sets of behavior is a non-linear one; vivid imagers tend to be-have as they do when they perceive bu t poor imagers behave similarly an d dis-similarly.

    Findings run contrary to the theorizing of Bartlett ( 1932 ) , McKellar(1957), and others that imagers are Ss who confabulate or import material notin the original perception. W he n memorial responses were unamb iguously de-fined and in itial perceptions controlled, the evidence strongly sup ported t he posi-tion that the imager is not a confabulator but rather one who accurately repro-

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    1030 P.W. SHEEHAN

    duces the orig inal stimulus as perceived. All three studies demonstrated the closefunctional correspondence between vivid imagery and perception.

    Stimuli typically used in imagery experiments do not lend themselves to theperc eption of all signific ant features. Sinc e imagery studies use pictor ial ma-terial, one may argue that very meaningful and interesting stimuli were omittedin the present experiments, hence an important source of confabulation was ex-cluded. O n the other hand, if the imager is inve ntive and images in a haphazardand spontaneous fashion, he should demonstrate this with geometrical figures.Th e experim ental stimuli used in the present studies do allow for confabulationand confabulation did occur but it accompanied poor imagery rather than vividimagery.

    The question of accuracy of recall in imagery is an important one that fo-cuses on the form in which experience is retrieved. T h e issue is relevant to thedegree to which experience is registered and subsequently revived in detail.Availability of experience to recall is subject to processing of some kind by theorganism. Th e end product of such processing can be termed a "representation."Bruner ( 1964) has discussed various modes of representation which reflect dif-feren t ways in which individuals handle cognitive data. On e way of representingexperience is the "iconic representation" which "summarizes events by the or-ganization of percepts and of images, by the spatial, temporal, and qualitativestructures of the perceptual field and their transformed images" ( Bru ner, 1964,p. 2 ) . Imagery is an impo rtant vehicle of representation of past experience. I tcan stand for perceptual events in the way that a picture represents an objectpreviously perceived. Considered in this way, the problem of sto ring experi-ence becomes less important than how experience is retrieved and in what form.Results in the present set of experiments are relevant to these questions; theyshow that imaging Ss can retrieve the stimulus content offered for perception ina way which reflects the accuracy of the original material.

    Ss given imaging and recall instructions showed different memorial ac-counts of the perceptual stimulus. Ima ging behavior was more akin to perce pm -a1 behavior than recall behavior. Th is find ing draws attentio n to the need fo rcloser scrutiny of memorial accounts of introspecting Ss and the differentiationof imaging from non-im aging recall.

    Familiarity alone cannot account for individual differences in vividness rat-ings. Practic e only increased the variance of individu al differenc es already exist-ing regardless of Ss' experience with th e imaged object. W it h increasing famili-arity with the experimental stimulus, the ratings of Ss with vivid imagerychanged systematically in the direction of the mo re vivid. Ratin gs given by SSwith poor imagery were relatively independent of practice.

    Vividness of imagery bears some relationship to the degree of complexityof the stimulus. More comp lex stimuli were not imaged as vividly as less com-plex stimuli. Oth er stimulus characteristics such as stimulus mean ing need ex-

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    IMAGING AND PERCEIVING : INDIVIDUAL DIFFERENCES 1031plicit study. Since experimental stimuli were perceived by Ss as having somepatte rning , in one sense they may be called meaningful. In anothe r sense ma -terial is me anin gful if it has ego reference fo r Ss perceiving it. Th e problem ofrecall of e go refer ence mate rial is of special importa nce in the study of dre amimagery and hypnagogic imagery where primary process and drive organizedactivity is aroused. Futu re study may show thac con fabu lation accom panies vividimagery only when stimuli are particularly relevant to Ss' motivational struc-tures. Results from the present studies indicate that an investigation of thisque stion needs to consider carefully all the possibilities of perceptio n. U nde rmotivational infloence percep tion may be selective or illusory. In these in-stances inferences about the stimu lus accuracy of imagery can be m ade onlywith caution.

    The present set of investigations do not account for the correspondence be-w e e n imaging a nd perceiving; they assert only that a behavioral correspondenceexists and state something about the form it takes. Th e causative mechanismsbehind the behavioral differences between good and poor imagers are a separate,but important issue.Th e hypothesis that sim ilar mechanisms underly the processes of imagingand perceiving may explain the close correspondence between imaging and per-ceptual behavior. Since similarity betwee n imaging and perceptual behaviordoes not necessarily warrant the conclusion thac perceiving is thus like imagingin process, one must have other grounds for inferring that the functional cor-resp onde nce is due to an identity of process. Prop er study of th e hypothesisof process similarity requires that the imaging response be critically selected; itmu st be a response which is typically an effect of pe rcep tion. Silch responsesare those which indicate the aftereffeccs of prolonged perceptual stimulation:negative afterimages, illusions, and figural aftereffeccs.

    Studies supporting a similarity of mechanism underlying imaging and per-ceiving (Barber, 1959; Malhotra, 1958; Sarbin & Andersen, 1963) have beenmethodologically unsound. They have not determined w hether, or not, resultsare explicable in terms of S's knowing the expected response and giving the re-sponse which E wanted. In an attem pt to investigate explicitly the genuinenessof the imaging response a study by Singer and Sheehan (1965) failed to sup-port the process similarity hypothesis. It appears that the beha vioral similaricybetwee n imag ing and perceiving canno t be accounted for in terms of a similarityof process. Afte reffe cts of ima ging are observed only wh en S expects that theyshould occur.

    An alternative explanation of results lies in the exploration of individualdifferences in modes of representation of experience. Poor imagers may proc-ess their experience differently from vivid imagers, employing more symboliclevels of rep resentation such as coding. Symbolic devices used to code materialcould lead poor imagers into error when they attempt to reproduce complex visu-

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    1032 P. W. SHEEHANa1 arrays. Th e vivid imager builds his representation upo n perceptual organiza-tion which records initial experience step by step; he is tied to the immediacy ofhis experience while the poor imager can represent his experience symbolicallyin a way that takes him beyond what Brunet (1964) calls the "point-at-able" orimmed iate present. I n this sense confabulation, or the introdu ction of new ma-terial into the memorial response, may be expected to accompany poor ratherthan vivid imagery.

    In conclusion, individual differences in vividness of imagery are related todifferences in correspondence between imagin g and perceptual behavior. Th isdemonstrates a functional similarity between imaging and perceiving. Vividimagery is not typically characterized by confabulation but tends to reinstitutethe accuracy of th e perceiving process. Th e most plausible explanation of re-s ~ ~ l t seems to lie with the variables underlying individual differences in modesof representation rather than with the study of identity of the mechanism under-lying the two processes.

    REFERENCESA N G ELL,J. R. Methods for the determination of menral imagery. Psychological Mono-graphs, 1910, 13, 61-107.BARBER,T.X. The after images of "hallucinated" and "imagined" colors. Journal ofAbnormal and Social Psychology, 1959, 59, 136-139.BARRATT,P. E. Imagery and rhinking. Australian Journal of Psychology, 1953 , 5, 15 4-164.BARTLETT,F. C. Remembering. London: Cambridge Univer. Press, 1932.BERG, ., & W O R C H E L ,. Sensory contributions to human maze learning: a comparisonof matched blind, deaf and normals. Journal of General Psychology, 1956, 54,

    81-93.BETTS,G .H. Th e distribution and functions o f mental image ry. New York: ColumbiaUniver. Teachers' College, 1909. (Contributions to Education Series, No. 2 6 )BRUNE R,J. S. The course of cognitive growth. American Psychologist, 1964, 19, 1-15.FERNALD,. R. The diagnosis of mental imagery. Psychological Monographs, 1912, 14 ,1-169.HICKS,D. On the nature of images. British Journal of Psychology, 1924, 15, 121-148.KOHS, . C. Intelligence measurement. New York: MacMillan, 1927.KUHLMANN,. On the analysis of the memory consciousness for pictures of familiar ob-jects. American Journal o f Psychology, 1907, 18, 389-420.LINDQUIST,. F. Des ign and analysis o f experimen ts in psychology and education. Bos-ton: Houghton Mifflin, 1953.MALHOTRA,. K. Figural after-effects: an explanation of Koehler's theory. Acta Psy-chologica, 1958, 14, 161-199.MCKELLAR,. Imagination and thinking. New York: Basic Books, 1957.MOORE,T. V. Image and meaning in memory and perception. Psychological Mono-graphs, 1919, 27, 67-296.ORNE,M. T. The nature of hypnosis: artifact and essence? Journal of Abnormal and So-cial Psychology, 1959, 58, 277-299.SARBIN, T. R., & ANDERSEN,. L. Base rare expectancies and perceptual alterations inhypnosis. British J ournal o f Social and Clinical P sychology, 1963, 2, 112-121.SHEEHAN, . W . The investigation of visual imagery an d some of its correlates. Un-published doctoral dissertation, Univer. of Sydney, Australia, 1965.

  • 7/28/2019 articolo immagini mentali


    I M A G I N G A N D P E R C E I V I N G : INDIVIDUAL DIFFERENCES 1033SIEGEL,S. Non-parametric sratirticr for the behavioral sciences. New York: McGraw-Hil l , 1956.SINGER, . , & SHEEHAN, . W . Th e effect of deman d characteristics on the figural after-effect with real and imaged inducing figures. American Jousnal of Psychology,

    1965, 78, 96-101.SUTCLIFFE, . P. A general merhod of analysis of frequency data for m ultip le classifi-cation designs. Psychological Balletin, 1957, 54, 134 -137.TITCH EN ER, . B. A textbook of psychology. New York : MacMillan, 1919.WO O D WO RTH , . R . Expwimental psychology. New York: Hol t , 1938.W U N D T ,W. M . Grundriss de r Psychologie. Leipzig: Kroener, 1918.ZACHARIAH, . A study of accuracy of reprodu ction of visual images a t various age levels.Journal of Psychological Research, 1958, 2 , 42-49.Accepted September 30, 1966.