articolo immagini mentali

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    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 examinati