Are
There People Who Do Not Experience Imagery?The material below comes from a long post that I made (on Sat, 22 Dec 2001) to the Psyche-D email (theoretical issues of consciousness research) discussion forum. I was replying to some questions asked in the forum by John Preston. There used to be a direct link from this site's home page to the relevant page in the online archives of Psyche-D, but the forum itself was recently (in October 2007) closed down, and the archives appear to have become unavailable. Luckily, though, I kept a copy of my post, and am able ressurect it here. To the best of my knowledge, with the exception of Galton's original work (1880, 1883), Sommer's brief case study (1978), and Faw's (1997) article, this is the only really substantial discussion of the phenomenon of non-brain-damaged "non-imagers" available anywhere.
The passages in dark red are Preston's questions, as I quoted them in my reply. Apart from updating the links and references, where needed, and adding one or two minor clarifications (in square brackets and in green), I have not done anything to change the substance of what I wrote in 2001. However, I have added an addendum at the bottom of the page detailing and discussing a few pieces of relevant information that have appeared (or come to my attention) since that time.
John Preston wrote:
I'm aware of the existence of a large amount of recent research, from a
cognitivist point of view, on mental images. But does anyone know:
(i) whether there are people who claim not to have mental images (not
just visual images) at all?
If complete non-imagers (who are otherwise normally conscious and mentally competent) really could be proven to exist, that would be of great theoretical importance. At least since the time of Aristotle (see De Anima 431a 15-20), it has been very widely held (by both theoreticians and "the folk") that the experience of thinking consists largely or entirely in the vicissitudes of mental imagery, although it has long been clear, from consideration of the mental abilities of the congenitally or long-time blind, that it is not essential that any of this imagery be visual (even in the sighted other imagery modes may be more important than is commonly realized (Newton, 1982), and verbal imagery, in particular, plausibly plays a very large role in most human thinking (Paivio, 1971, 1986)). Of course, Cognitive Science has by now provided us with a rich set of alternative accounts of the underlying mechanisms of thought - of what might be going on under the surface, as it were - but it is not clear that even now we have any developed alternative account of the conscious experience of thinking available to us. When contemporary cognitive scientists come to consider conscious thought rather than underlying mechanisms, they return to the idea that it is embodied in imagery (e.g. Damasio, 1994). The utopian fantasies of the Churchlands notwithstanding, I do not believe that there is anyone who seriously claims to be directly conscious of their thinking as being embodied in mentalese, or weight space vectors, or patterns of neuronal excitation, or any of the other sorts of cognitive mechanisms that are discussed. (Theorists like Mangan (2001), James (1890), and the Wurzburg school psychologists (Thomas, 2001) may or may not be right to hold that not all aspects of the conscious experience of thinking can be characterized in terms of imagery, but I do not think they are arguing that it imagery is not an essential component of conscious thought.) If true and total (and mentally competent) non-imagers really exist, then the imagery theory of conscious thought would be refuted. I suspect something like this consideration is what motivates John Preston's question.
Certainly it is largely for this reason that I have taken a considerable interest in the issue of "non-imagers" over many years now. Unfortunately, so far as I have been able to discover (and I have looked, and have asked those who might be expected to know), although the existence of people who deny having visual imagery has been known to science for well over 100 years (Galton, 1880, 1883), no systematic research whatsoever has been done on the phenomenon. I have not even been able to find any reliable figures for the incidence in the general population of visual "non-imagers" (Abelson (1979) quotes a figure of 10-12% , but gives no hint of where this figure comes from - if anyone knows of a better source on this point, please let me know!). Furthermore, even the rare anecdotal accounts of "non-imagers" that I have found in the scientific literature seem to focus almost entirely on visual imagery. This may be largely because "imagery" is often understood as meaning visual imagery, both by scientists and by ordinary folk. Although psychologists will sometimes talk about auditory imagery, haptic imagery, "motor imagery" and the like, it is not obvious that this accords with ordinary usage very well. (Scientific studies of any sort concerning non-visual imagery, although they do exist, are quite thin on the ground.)
There are accounts in the neurology literature of people who have apparently retained their vision but lost their ability to experience visual mental imagery after brain damage, but of course, these people are mentally impaired in other, usually more obvious, ways. (I could dig out some references for you if you want, but I am not aware of any neurological case studies of people who have lost imagery in another sense mode. See Richardson (1999 ch.2) for a brief and selective literature review.) Inevitably, however, introspective phenomenological reports from brain damaged subjects need to be treated with great caution. For reasons to be explained below, introspective reports on these sorts of matters are very problematic to evaluate even for neurologically healthy subjects. Clearly things are much worse when dealing with the brain damaged, who may often suffer subtle and not-so-subtle language deficits, and who, in some cases, will insist they can see perfectly when they are clearly blind (Anton's syndrome - Young & de Haan, 1990), will insist they are blind when they can clearly see (Hartmann et al., 1991 [This is not the now well-known blindsight syndrome. This is a man who, although certainly visually impaired, rides a bicycle in the streets and writes and uses shopping lists, but still insists he can see nothing.]) or will deny the fact that they are paralyzed (anosognosia - Ramachandran, 1995).)
Apart from such neurological cases, however, anecdotal accounts of non-imagers in the psychology literature not only seem to confine themselves to the visual mode, they also raise doubts about the reality (or stability) of the phenomenon. It appears that on more probing questioning such people will generally admit to experiencing at least some visual imagery, particularly in dreams (Galton, 1880, pp. 305-306; Galton, 1883, pp. 91-92; Marks, 1972, p. 107; Sommer, 1978, chap. 7). David Marks, who is very arguably the leading contemporary researcher into individual differences in the conscious experience of visual imagery has even suggested to me (personal communication) that non-(visual)-imagers may be suffering from some sort of sub-clinical neurological disconnection syndrome, whereby they do have visual imagery, but are unable to report it.
I can add something to this anecdotal evidence, because I have been running a web site devoted to the cognitive science of mental imagery since 1997, and over that period I have received a number of email messages, and, latterly, message board postings, from people who say they lack imagery (by which they seem to mean visual imagery). I have attempted, sometimes with some success and sometimes not, to engage these people in a dialogue about their condition, although I have not always been able to get very clear answers, and in some cases, like Marks and Sommer, I have found that they backpedal on their claims somwhat when pressed. However, I have also noticed that some of these people seem to be quite concerned about their condition, and to be looking for a "cure" - they seem to believe that lack of imagery renders them less imaginative, or something like that. Others seem to be quite content with, or even proud of their condition. I even recently heard from someone who claims that the condition runs in their family. (For reasons that should become apparent below, I do not think this necessarily implies that it is a genetic condition; it might be something more like a family tradition.) One particularly interesting case was a psychology student, Carlos, who had just recently realized that most other people believe they experience visual imagery. He was quite excited, thinking he might have discovered in himself a phenomenon new to science, until he came across the material on my web site. I managed to get more feedback from him than from most of the other cases I have encountered, and did manage to ascertain that he does experience imagery in non-visual modes: he "hears" tunes in his head, for instance. However, on asking about how his thought processes subjectively seem to him (particularly thinking about spatial relations, or remembering the appearance of things) I was not able to get anything much more revealing from him that the claim that he "thinks in concepts" and that he knows what things look like (which is no doubt true, but did not much enlighten me). Some of my other exchanges with non-imagers can still be found online on the back pages of my web site message board at http://forum.asiaco.com/im-im/ [sorry, this board no longer exists]. One topic pursued there is how people who claim that they experience visual imagery only in dreams remember (without waking imagery) that they do have the imagery in their dreams. I cannot, however, recall ever managing to elicit a clear declaration from anyone that they lack imagery in all sensory modes.
Nevertheless, I am fairly confident that, if you searched diligently, and phrased your questions artfully, you could find people who would claim that do not experience imagery of any sort whatsoever. Some might even insist on the point quite vehemently. The trouble is, all such introspective reports about personal, idiosyncracies of subjective experience need to be treated with great caution. We should be wary of resting very much theoretical weight upon them (which is not to say that they should be disregarded altogether). Although, no doubt, there are real differences between different people's subjective lives, there is also much reason to believe that introspective reports about such matters are strongly influenced by cultural forces and by theoretical preconceptions (whether coming from formal psychological theory, "folk" psychological tradition, or even personal pet theories) about what subjective experience ought to be like. Psychodynamic or emotional factors may well also significantly affect these reports: perhaps some people "repress" their imagery experience (in a more or less Freudian sense), but does that mean that they do not have such experience, or just that they do not like to talk or even think about it?
As evidence for the influence of theoretical factors, consider the fact that J.B. Watson, before he developed his Behaviorist metatheory (until at least late 1908), was insisting that his "centrally aroused visual sensations [i.e., visual mental images] were as clear as those peripherally aroused" (Watson, 1913 n.7), but by 1913, when he published his famous Behaviorist manifesto, he was questioning, and soon after outright denying, the very existence of imagery (Watson 1913a, 1913b), eventually stigmatizing the very concept as "sheer bunk" (Watson, 1928) and "medieval" superstition (Watson, 1930). I have discussed the circumstances surrounding this rather radical change in Watson's claims about his own subjective experience, and the reasons for it (including the conceptual confusions that seem to be involved), in an article I published some years ago (Thomas, 1989). It would be implausible to ascribe it either to dishonesty on Watson's part (suppressing subjective evidence that contradicted his new theory) or to an actual change in the workings of his mind; rather what we see here is a rather stark exemplification of how theoretical ideas about psychological matters can radically shape how we conceptualize and report upon our subjective experience.
Of course, Watson's (later) views were very influential, or, at least, he was riding the crest of a wave of historical intellectual change. The abrupt change in Watson's claims about his subjectivity would soon be mirrored in the psychological profession as a whole, and subsequently in allied disciplines. It was also foreshadowed (and partly caused) by the "imageless thought controversy" which raged amongst the introspective psychologists during the first decade of the 20th century (Thomas, 2001). On one side (to simplify the story somewhat) were Oswald Külpe and his students in Würzburg, Germany, and on another we find Edward Titchener and his students at Cornell. Although the Würzburg introspectors did not deny that they experienced mental imagery, they insisted that they also experienced other types of conscious contents (designated by jargon terms such as bewusstseinslagen, but rather vaguely described as, for example "an impalpably given knowing"), the Cornell introspectors categorically denied that such "imageless" contents existed, and insisted that more careful introspection revealed fleeting (perhaps non-visual) imagery or subtle bodily sensations in their place. Needless to say, the results obtained in each laboratory fitted very nicely with the theoretical commitments of the respective presiding professors. This fact did not go unnoticed, and contributed significantly to the loss of confidence in introspective methods, the concomitant decline in scientific interest in imagery, and (in America) the rise of Behaviorism.
Between about 1920 (in the wake of the imageless thought controversy and Watson's polemics) and 1960 I think you would have been hard pressed to find an experimental psychologist in the U.S.A. who would admit to experiencing vivid and copious imagery, and probably a very high proportion would have denied experiencing any sort of imagery whatsoever (with the possible exception of "inner speech"). In the years since the 1970s, and a fortiori before about 1913, when a "non-imager" could scarcely have functioned as a psychologist, you would certainly find things quite otherwise (Holt, 1964; Kessel, 1972; Thomas, 1989, 2001, 2003).
There is evidence for a similar historical pattern, but displaced a few decades forward, amongst both 20th century philosophers and literary critics. Heil (1998 p. 213), notes that contemporary philosophers are very much "inclined to downplay the significance of imagery. . . . In discussions of mental imagery, it is common for discussants to claim that their imagery is dramatically attenuated, or even altogether absent. (In some quarters a professed lack of imagery is worn as a badge of honor.)" (This anecdotal evidence of Heil's certainly jibes with my own experience, and may be further supported by a much earlier anecdote from Price (1953 p. 234).) As Heil is well aware, contemporary philosophers, in this regard, are at odds not only with "the folk", but with nearly all philosophers of previous ages, who regarded imagery as a crucial aspect of cognition (Thomas, 1997, 1999b, 2001, 2003; see also Brann, 1991; Jay, 1993). In Heil's view, rather than reflecting a true difference in subjective experience between contemporary philosophers and earlier ones (and most of 'the folk'), these informal introspective reports are actually much more the result of "what psychologists call a criterion difference, a difference in what we take to constitute imagery". (For the literary critics, see Esrock (1994) and, as evidence of a nascent return swing of the pendulum, Scarry (1999).)
It is not, I think, plausible to believe that these historical changes (within particular intellectual milieux) in what is informally said about said about the mind's contents, reflect actual fundamental changes in everyone's cognitive mechanisms. Nor is it reasonable to think that people were being widely and systematically dishonest in describing their inner experience during one or other of these periods, hypocritically conforming to what they thought would be acceptable to their peers. It is much more plausible to believe that they reflect changes in how the people concerned were inclined to conceptualize their minds' workings, and, thus, to describe them verbally, to themselves as well as to others. I see no reason to think that lay-people cannot be similarly affected by theoretical ideas of a less formal sort (and acquired in less systematic ways).
Weight is added to these speculations by the work of Schwitzgebel (2002a), who has noted a rather similar phenomenon in reports of dreaming. In the 1950s it was widely reported by psychologists that a majority of people's dreams were largely or entirely without color: they were experienced in monochrome. More recent evidence, from the 1960s and later, indicates to the contrary that most people believe themselves to dream in color. It seems fairly clear that this change was not a result of changes in the way people's brains function, but rather to changing cultural influences affecting how they conceptualize and report their subjective experience (and perhapsi n how psychologists questin them and interpret their answers). The cultural change that Schwitzgebel points to is the prevalence of black and white television in the period when dreams seemed to be in black and white, and its later replacement by color television. I would suggest that other factors may have been at work as well, including the generalized iconophobia of the still deeply Behavioristic American psychology of the 1950s, which had probably seeped somewhat into the popular mind as well.
Schwitzgebel also argues explicitly (2002b) that we really do not know much about what our own mental imagery is like. I find the position as he states it rather extreme and paradoxical, but his arguments certainly lend weight to the view that I have been arguing that we are really not very good at accurately reporting what our private subjective experience is like. Just because it is private, it is hard to be sure that we are applying the words we use to describe it in the same way that the next person does. In attempting this difficult descriptive task we are inevitably affected by our formal or informal theoretical conceptions of how the mind works.
Indeed, if we did not have some such theoretical preconceptions it is questionable whether we would be able to describe the contents of our consciousness at all. The language in which we describe our subjective experience derives entirely, or almost so, from our theories; after all, one could hardly build up a vocabulary for discussing private experience via ostensive definition. Although I think it is mistaken (Thomas, 1999a), the traditional inner 'picture' theory of visual imagery that is entrenched in 'folk' psychological thinking has perhaps served a useful purpose over the centuries by giving people a certain confidence that they are talking sense when they talk about visual imagery experience. At the very least it has given them a vocabulary for talking about such experiences. It is no coincidence, I think, that the reluctance of so many mid-to-late 20th century philosophers to admit to experiencing imagery has gone along with a widespread rejection of picture theory (following the work of Ryle and Wittgenstein) coupled with the absence (at least before Pylyshyn came along) of any clear and convincing alternative explanation of quasi-perceptual experience. The absence of any traditional equivalent to picture theory for explaining quasi-perceptual experience in the other sense modes may go some way towards explaining why non-visual imagery is relatively rarely discussed.
I should probably add, at this point, that the fact that I believe that although I believe that people's attempts to describe idiosyncratic aspects of their imagery experience are thoroughly "theoretically infected", it does not follow that there is no real phenomenon behind them. The eliminativist line taken towards imagery by psychological and philosophical behaviorists has long since proved itself quite inadequate not only to accounting for people's actual subjectivity, but also to accounting for what is now a large and diverse arrary of experimental findings that demonstrate the cognitive effects of imagery: the powerful mnemonic effects of imagery (Paivio, 1971, 1991) probably remain the most important in this regard, but a wide range of other findings (see Finke, 1989; Richardson, 1999) also bear out the point. (Pylyshyn's well known arguments do not, and are not intended to, controvert this. Pylyshyn frequently makes it quite clear that he fully accepts that people have quasi-visual experiences of the sort colloquially called imagery, and he also holds that the representations that embody this imagery have an important functional role to play in cognition. What he is rejecting is merely the view that such representations are in any meaningful sense similar to pictures.)
John Preston:
(ii) whether any psychologists, save for the most radical behaviorists,
deny either that people have mental images, or that mental images can
serve to produce or guide behavior (as goals, for example)?
The only significant psychologist that I know of who explicitly took such a position was J.B. Watson (see above for references); and even he hedges in places. There probably were other Behaviorists who made similar remarks, but as Glen Sizemore quite rightly points out, even so radical a Behaviorist as B.F. Skinner acknowledged the reality of "private seeing", although, of course, he was unwilling to call it mental imagery, and I do not believe he accorded it anything like the same sort of functional importance that it had for most cognitive theorists (philosophers and psychologists, from Aristotle to Hume to Bergson, Wundt, and Titchener) before the Behaviorist revolution. The iconophobia of the Behaviorist era, which still lingers on in an attenuated form in philosophy and much of cognitive science, is not so much a matter of the explicit denial of the existence or even the importance of imagery; it is simply a matter of ignoring the phenomenon as far as is possible, and treating it as trivial when it cannot be ignored.
John Preston:
(iii) where I might find good literature on questions like this.
As Preston is probably well aware, the literature of the well known "analog/propositional" debate, as discussed in the collections edited by Block (1981a, 1981b), by Tye (1991), and in many publications by Pylyshyn, Kosslyn, Anderson, and others (for further citations see Thomas, 1999a, 2001), is almost totally irrelevant to the questions he asked (and to the issues that I suspect motivate them). Despite its fame and its complexities, this debate was, to all intents and purposes, focused on an extremely narrow issue. It was about what sort of computational (or, latterly, neurological) mechanisms would best reconcile the phenomenological and experimental data about imagery with the computational-functionalist view of the nature of the mind. Kosslyn, Pylyshyn, Anderson, Shepard, Block, Tye etc. are concerned with the nature of the cognitive mechanisms that give rise to mental imagery, and only very indirectly, if at all, with the issues that Preston's questions raise, about individual differences in the conscious experience of imagery, and the functional role of imagery (as consciously experienced) in our thought processes. (In my view the phenomenological and experimental data about imagery cannot be reconciled with a computational-functionalist view of the mind, and thus both the "quasi-pictorial" and the "propositional/descriptional" theories of imagery are false and need to be replaced by a "perceptual activity" account which is not dependent upon functionalist token-token identity theory, but that is another story (Thomas, 1999a).)
In fact, I do not think there is any literature that is entirely on point for Preston's first question. Indeed, there is not much literature on (non-brain damaged) "non-imagers" at all. However, Thomas (1989) does provide a historical case study and theoretical discussion of the matter, and Galton (1880, 1883), Marks (1972), and Sommer (1978, chap. 7) provide anecdotal accounts of non-(visual)-imagers. If anyone is sufficiently intersted, I can supply a copy of the online exchange I had with Carlos the non-imaging psychology student (it was conducted publicly, on a now defunct web message board). See Richardson (1999 ch.2) for the brain damaged cases.
I think that is pretty much it for "non-imagers". However, there is extensive work on less radical individual differences in imagery, particularly on reported vividness differences (see Marks (1999) and Richardson (1999) for recent reviews). Also, I believe that research on different peoples' preferred imagery mode (visual, auditory, motor, etc. - what was known as "imagery type") was quite extensively pursed in the early years of the 20th century. I do not have the references for that at my fingertips, but Schlaegel (1953) might provide a place to start looking. [A better place would be: Fernald, M.R. (1912), The Diagnosis of Mental Imagery, Psychological Monographs v.14 #1 (Whole #58).]
For the essentially negative answer to the second question, see Thomas (1989, 2001, 2003, 1999b 1997), McMahon (1973) and perhaps Brann (1991).
I'm sorry for having gone on so long, especially as I am probably not giving Preston the answer he was hoping to hear, but it is so rare to come across someone who realizes the theoretical significance of this topic. I only wish that there were some substantial empirical work on non-imagers available. Does anyone have a grad student in search of a research project?
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Abelson, R. P. (1979). Imagining the purpose of imagery. Behavioral and Brain Sciences, 2, 548-549.
Block, N. (Ed.) (1981a). Imagery. Cambridge, MA: MIT Press.
Block, N. (Ed.) (1981b). Readings in Philosophy of Psychology, Vol. 2.London: Methuen.
Brann, E.T.H. (1991). The World of the Imagination: Sum and Substance.Savage, MD: Rowman & Littlefield.
Damasio, A.R. (1994). Descartes' Error: Emotion, Reason, and the Human Brain. New York: Putnam.
Esrock, E.J. (1994). The Reader's Eye: Visual Imaging as Reader Response. Baltimore, MD. Johns Hopkins University Press.
Galton, F. (1880). Statistics of mental imagery. Mind, 5, 301-318.
Galton, F. (1883). Inquiries into Human Faculty and its Development.London: Macmillan.
Hartmann, J.A., Wolz, W.A., Roeltgen, D.P., & Loverso F.L. (1991). Denial of Visual Perception. Brain and Cognition, 16, 29-40.
Heil, J. (1998). Philosophy of Mind. London: Routledge.
Holt, R. R. (1964). Imagery: The return of the ostracized. American Psychologist, 19, 254-266.
James, W. (1890). The Principles of Psychology. New York: Holt.
Jay, M. (1993). Downcast Eyes: The Denigration of Vision in Twentieth-Century French Thought. Berkeley, CA: University of California Press.
Kessel, F.S. (1972). Imagery: A Dimension of Mind Rediscovered. British Journal of Psychology, 63, 149-62.
Mangan, B. (2001). Sensation's Ghost: The Non-sensory 'Fringe' of Consciousness. Psyche , 7. URL: http://psyche.cs.monash.edu.au/v7/psyche-7-18-mangan.html
Marks, D.F. (1972). Individual differences in the vividness of visual imagery and their effects. In P. W. Sheehan (Ed.), The Function and Nature of Imagery (pp. 83-108). New York: Academic Press.
Marks, D.F. (1999). Consciousness, Mental Imagery and Action. British Journal of Psychology, 90, 567-585.
McMahon, C.E. (1973). Images as Motives and Motivators: A Historical Perspective. American Journal of Psychology, 86, 465-490.
Newton, N. (1982). Experience and Imagery. The Southern Journal of Philosophy, 21, 475-487.
Paivio, A. (1971). Imagery and Verbal Processes. New York: Holt, Rinehart and Winston. [Reprinted in 1979 -- Hillsdale, NJ: Erlbaum]
Paivio, A. (1986). Mental Representations: A Dual Coding Approach. New York: Oxford University Press.
Paivio, A. (1991). Dual Coding Theory: Retrospect and Current Status. Canadian Journal of Psychology, 45, 255-287.
Price, H.H. (1953). Thinking and Experience. London: Hutchinson.
Ramachandran, V.S. (1995) Anosognosia in Parietal Lobe Syndrome, Consciousness and Cognition, 4, 22-51.
Richardson, J.T.E. (1999). Mental Imagery. Psychology Press: Hove, U.K.
Scarry, E. (1999). Dreaming by the Book. Princeton NJ; Princeton University Press.
Schwitzgebel E. (2002a). Why Did We Think We Dreamed in Black and White? Studies in History and Philosophy of Science, 33, 649-660. Online at http://www.faculty.ucr.edu/~eschwitz/SchwitzAbs/DreamB&W.htm
Schwitzgebel E. (2002b). How Well Do We Know Our Own Conscious Experience? The Case of Imagery. Journal of Consciousness Studies, 9, 35-53 Online at http://www.faculty.ucr.edu/%7Eeschwitz/SchwitzAbs/Imagery.htm
Schlaegel, T.F. (1953). The Dominant Method of Imagery in Blind as Compared to Sighted Adolescents. Journal of Genetic Psychology, 83, 265-277.
Sommer, R. (1978). The Mind's Eye. New York: Delacorte Press.
Thomas, N.J.T. (1989). Experience and Theory as Determinants of Attitudes toward Mental Representation: The Case of Knight Dunlap and the Vanishing Images of J.B. Watson. American Journal of Psychology, 102, 395-412. [Available online at http://www.imagery-imagination.com/dun-wat.htm ]
Thomas, N.J.T. (1997). A Stimulus to the Imagination. Psyche , 3. On-line serial, URL: http://psyche.cs.monash.edu.au/v3/psyche-3-04-thomas.html
Thomas, N.J.T. (1999a). Are Theories of Imagery Theories of Imagination? An Active Perception Approach to Conscious Mental Content. Cognitive Science, 23, 207-245. [Available online at http://www.imagery-imagination.com/im-abs.htm ]
Thomas, N.J.T. (1999b). Imagination. In C. Eliasmith (Ed.) Dictionary of Philosophy of Mind. Online publication. URL: http://philosophy.uwaterloo.ca/MindDict/imagination.html
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Thomas, N.J.T. (2003). Imagery, Philosophical Issues about. In L. Nadel (Ed.) Encyclopedia of Cognitive Science. London: Macmillan/Nature Publishing. [Penultimate draft online at http://www.imagery-imagination.com/mipia.htm ]
Tye, M. (1991). The Imagery Debate. Cambridge, MA: MIT Press.
Watson, J.B. (1913a). Psychology as the Behaviorist Views It. Psychological Review, 20, 158-177. [Available online at http://psychclassics.yorku.ca/Watson/views.htm ]
Watson, J.B. (1913b). Image and Affection in Behavior. Journal of Philosophy, Psychology and Scientific Methods, 10, 421-8.
Watson, J.B. (1928). The Ways of Behaviorism. New York: Harper.
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Young, A.W. & de Haan, E.F. (1990). Impairments of Visual Awareness. Mind and Language, 5, 29-48.
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Nigel J.T. Thomas Ph.D.
The paragraphs below discuss further information on the topic of non-imagers that has appeared, or has come to my attention, since the above post was written in 2001. Unfortunately, it only serves to make it even more clear how little is understood about the matter.
(i) Burbridge (1994) has examined Galton's private papers, and from them is able to fill in many details of Galton's researches on mental imagery, and to give a much more complete account of them than is available from Galton's own publications (1880, 1883). (Amongst other things, Burbridge is able to identify most of the individual "distinguished scientists" and other intellectuals who responded to Galton's questionnaire on imagery, and to tell, at least in general terms, and sometimes more specifically, how each of them actually responded.) This is important because not only was it Galton's work that first brought the possibility that some people might lack imagery to scientific and scholarly attention, but it is still by far the best known account of the phenomenon. Much weight has been put upon Galton's brilliant and pioneering research, but it is not without its flaws. Galton's own claims are often stronger than the data seem to warrant, and sometimes secondary accounts based on his work exaggerate them further.
(ii) Brewer & Schommer-Aikins (2006) re-analyzed Galton's original data and also attempted to replicate his findings on the imagery of scientists with a new study closely based on his original design. They found that neither Galton's original data nor their own results supported Galton's (1880, 1883) well known claim that scientists are more likely than other people to be non- (or very poor) imagers. Galton appears to have mis-analyzed his own data, and Brewer & Schommer-Aikins, in their own study, found "no scientists totally lacking in visual imagery and very few with feeble visual imagery." Galton's sample does seem to have included a handful of individuals claiming to have no visual imagery whatsoever (see iii below), but his data certainly do not justify the oft repeated conclusion that this condition is common amongst scientists. Brewer & Schommer-Aikins (2006) provide many examples of published second-hand reports of Galton's claims about the imagery of scientists (and we can add to their list, Sommer (1978 p. 1)). Often, these do not just repeat Galton's erroneous conclusion, but state it in considerably stronger terms than he did.
(iii) Kosslyn
(1980 p. 399) says that, according to Galton, non-imagers form "slightly
over 10 percent" of the general population, and in a later work (Kosslyn,
1983 p. 195) this figure has risen to "about twelve percent." It seems
likely that Abelson (1979) got his figure of 10-12% from the same source. However,
it looks to me as though these numbers are based of a flawed reading of
Galton's findings (no doubt having been misled by Galton's own inacurate acount
of his results, as detailed by Brewer & Schommer-Aikins (2006)). In fact
Galton initially seems to have categorized some 13 of his sample of 100 "distinguished
men" (scientists
and others) as having "very dim" imagery (Burbridge, 1994 p. 455).
There was no "no imagery" category in his data analysis, and although
the "very dim" group did include some who claimed to be total non-imagers
[certainly H. Lefoy and C.P. Smyth (Burbridge, 1994 p. 460), probably also G.W.
Romanes and John Herschel (Brewer & Schommer-Aikins, 2006), and possibly
more], it is clear from some of the actual responses quoted in Burbridge's article
that Galton also included several respondents in this group who were by no means
denying all experience of imagery. Also, of course, Galton was very far from
suggesting that this sample of 100 was typical of the general population, and
makes it quite clear that there were fewer (if any) non-imagers in the other
more representative samples he polled. To be fair to Kosslyn, his 1983 discussion
made it quite clear that he had grave doubts as to whether non-imagers were in
fact as common in the 1980s as (he thought) Galton had found them to be in the
19th century, and in a recent online interview Kosslyn (2002) has asserted that “less
than 2 percent” of
the modern population are non-imagers. However, he gives no indication whatsoever
of the source of this latter number, and I have not found any mention of it in
any of his more formally published writings, so it can hardly be regarded as
reliable. I suspect it is no more than an informed "guesstimate." Much
the same can be said for the figure of "probably less than 5%" given
by Faw (1997). Although he mentions not only Galton's (1880, 1883) studies, but
also Betts' (1909) more extensive early research on individual differences in
imagery, and unpublished work of his own, it is not clear that he is even claiming that
any of these provide direct support for the "less than 5%" figure (though
perhaps Galton's does, if my reading of Burbridge on Galton, above, is correct).
I have not been able to find any explicit claims about the incidence of non-imagers
in Betts' work, and for reasons that should now be clear, I do not think this
figure can be found in Galton's published work either. (Of course, I do not know
what might be in Faw's unpublished work, but if it truly supported the 5% figure,
surely he would have made the point more explicit).
In
fact, with so little real research available on non-imagers, the topic has degenerated,
even in the peer reviewed scholarly literature, into a game of Chinese Whispers.
Berman & Lyons (2007), for example, cite Brann (1991) as authority
for their claim that "contemporary psychologists" hold that about
2% of the general population are non-imagers. In fact, Brann (1991 p. 355)
gives a figure of 3%, citing Kosslyn (either 1980 or 1983 – it is not
clear which) as her source. In fact, as just discussed, Kosslyn gives figures
of 10% and 12% respectively in those works. Brann may be misunderstanding a
passage where Kosslyn (1983 p. 195) mentions (but does not properly cite!)
a study that apparently found that 97% of a sample of Mensa members claimed
to have "vivid imagery." It
does not, of course, follow (and I do not think Kosslyn means to imply) that
the other 3% had no imagery at all (and, of course, Mensa members are, ipso
facto, psychologically atypical of the general population). [I have reason
to believe that Berman & Lyons
actually got the 2% figure from me. An earlier draft of their paper, that
I critiqued for them, had 3%, as given by Brann, and in my commentary I questioned
this, and mentioned Kosslyn's (2002) figure of 2%. However, the published version
of their paper attributes the 2% figure to Brann, not Kosslyn. Wherever the
number comes from, they are certainly being misleading in implying that it
represents some sort of consensus.]
Update,
May 4th 2008: I have just come across a passage in A. Richardson's
(1969 p. 129) book that quotes the 10% figure and ascribes it to an article
by McKellar. I am going to do my best to obtain the McKellar article (which
may be difficult). However, I will be quite suprised if the figure does not
turn out to derive from Galton again.
(iv) Berman & Lyons (2007) have recently re-examined the historical evidence relating J.B. Watson's denial of the existence of mental imagery, which played an important role in the crystallization of his enormously influential Behaviorist approach to psychology. For the most part, their paper reiterates and reinforces the account of this affair that I published several years ago (Thomas, 1989). In particular, they agree that despite his public and sometimes vehement denial of the very existence of imagery from about 1912 onwards, Watson was not a non-imager. Rather, he was motivated to deny its existence by his strong theoretical commitments. Berman & Lyons (2007) do not think Dunlap's views on imagery had quite as much influence on the development of Watson's views as I suggested, and they give an account slightly different from mine of how and why Watson managed to persuade himself that his own imagery was unreal. However, although Watson may well have suffered from the "ideological blindness" that they ascribe to him, I am not persuaded that it would have been sufficient to lead him to deny his own direct experience in the way he seems to have done. It seems to me that something like the conceptual confusions that I ascribed to him in my article (Thomas, 1989) must almost certainly have also played a role.
(v) I have had several more email and message board communications from non-imagers since making the posting to Psyche-D. Some seemed to be offended by the Psyche-D post, taking it to be casting doubt on their veracity or mental competence, which was certainly not my intention. On the other hand, rather to my surprise, at least one of them seemed to like Marks' suggestion (mentioned below) that the non-imagers might really have imagery but, because of some sub-clinical disconnection lesion in the brain, are not able to consciously access it. She thought this did seem consistent with her introspections. Unfortunately her post to my message board at asiaco.com was lost when that board went dark, but as I far as I can remember she said something to the effect that it sometimes felt as though she was experiencing imagery, but it was somehow hidden behind a screen or veil. I am not sure what to make of this, but it is probably the most interesting introspective report on the topic that has come my way.
(vi) Since
I wrote the above, I have come across a paper, by Faw (1997), that directly and
centrally addresses the issue of non-imagers. Unfortunately it contains no new
empirical data, but Faw is apparently a non-imager himself, so he can add something
to the store of anecdotal evidence, and it certainly helps that he is able to
interpret his introspections in the light of the relevant psychological and neuroscientific
evidence and perspectives. He says he lacks waking imagery in all sensory
modes, not just the visual, but, like many other (perhaps all) unimpaired non-imagers,
he does report experiencing vivid dream imagery (including even lucid dreams*).
Faw tentatively concludes that non-brain damaged, non-impaired non-imagers like
himself do have mental images in the representational sense of the term (see
Thomas, 2007 §1.1 for
a discussion of the representational and experiential senses of "imagery"),
that is to say, they do form and make
use of the sorts of quasi-perceptual inner representations that are thought to
be necessary for certain cognitive performances, such as mental rotation, but
for some reason are unable to bring these imaginal representations to waking
consciousness. Faw also makes a number of speculative suggestions as to the possible
causes of such non-consciousness, ranging from the neurophysiological to the
psychoanalytic, but comes to no definite conclusion as to which, if any, of them
are likely to be correct. Like me, he would very much like to see some real
empirical research being done on the issue.
*Lucid dreams, are defined as dreams in which
the dreamer is aware that he or she is dreaming whilst the dream is in progress.
A lucid dreamer may also be able to exercise some conscious, voluntary control
over events in the dream.
– Nigel J.T.Thomas
Abelson, R.P. (1979). Imagining the Purpose of Imagery. Behavioral & Brain Sciences (2) 548-549.
Berman, D. & Lyons, W. (2007). The First Modern Battle for Consciousness: J.B. Watson's Rejection of Mental Images. Journal of Consciousness Studies (14 #11) 5-26.
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(2007). Mental Imagery. In E.N. Zalta (ed.), The Stanford Encyclopedia of
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URL:
http://plato.stanford.edu/archives/fall2007/entries/mental-imagery/
The most current version
of this article is at: http://plato.stanford.edu/entries/mental-imagery/
