Aphantasia November 2, 2015

We’re all familiar with the phenomenon of seeming to experience sensations of different sorts in the absence of the events being “sensed.” We respond as if we are seeing something – our dog, for example – even though it is clearly not present. B. F. Skinner (1953) discussed this topic from both respondent and operant perspectives in the context of seeing in the absence of the thing seen. Chapter 4 in Radical behaviorism for ABA practitioners addresses the topic in some detail, and I focused on the same issue in a post titled, “The mind’s eye and the voice in our head”(December 18, 2014).

Stripped of the usual mentalism, understanding what is going on when we do this requires distinguishing between the physiological aspects of sensing and the associated behavioral features of our sensory capabilities. External stimuli influence our behavior from birth, but we also learn to respond to such stimuli in particular ways. We don’t usually notice, but our repertoire of sensory behaviors gradually improves to the point that we are able to engage in the behavior of seeing, hearing, etc. with diminishing assistance from external stimulation. Most eventually master the skill of seeming to experience sensations with varying degrees of clarity in the complete absence of what is being sensed. We seem to do best at seeing visual “images” that are not present. The role of the verbal community in encouraging this skill is unclear.

It’s reasonable to assume that anyone with normally functioning sensory systems would learn to respond to varying degrees of external sensory stimulation, including engaging in such sensory behavior when the stimulation is faint or even not present at all. On the other hand, it also follows that someone who has always lacked a particular sensory capability would not learn to engage in its associated behavioral aspects.

Of course, most people would find it difficult to conceive of seeing, hearing, and so forth as forms of responding without assuming that there are always concurrent neurological events that are part of learning contingencies. When the external basis for such events is obviously absent, it’s tempting to assume that comparable stimuli are somehow still present neurologically. If so, their role as antecedents or consequences of sensory responding isn’t clear. On the other hand, it’s also not clear whether such neurological activity is required just because we can sense events that are not present.

What is aphantasia?

In any event, matters may be more complicated than this because some people with apparently normal sensory capabilities do not appear to emit the behavioral components of sensing in the absence of actual sensory stimuli. Some seem to fail to acquire this ability at all. This phenomenon was noted by Sir Francis Galton in 1880 but has generated little attention over the years. However, a recent study by Zeman, Dewar and Della Sala (2015) reported a survey of 21 self-selected individuals who contacted the researchers following an article by Carl Zimmer in Discover magazine (Zimmer, 2010), which was based on an article by Zeman and others (2010) about a man who lost this “imaging capability” following cardiac surgery. This topic has more recently generated attention from websites such as IFLScience and ScienceDaily.

Zeman and his colleagues administered a simple questionnaire to these 21 individuals. Most did not realize their limitations until they were in their teens or twenties. All but two were male and a quarter reported affected relatives. About half reported that all sensory modalities were affected, but all indicated substantial or complete inability to experience visual imagery. A majority of the participants reported involuntary visual imagery in flashes or in dreams. Zeman et al. labeled the deficit “aphantasia,” based on the Greek term “phantasia,” meaning imagination. A survey of 2,500 people by Faw (2009) suggests that this phenomenon might be found in up to 2.1% to 2.7% of the population.

What needs to be explained?

Zeman is described as a cognitive neurologist whose ongoing research focuses on the neural basis for visual imagery. Although this may be an appropriate research direction, it is also interesting to wonder about the behavioral basis for this phenomenon, which can apparently occur to varying degrees. Aside from the possibility that neurological anomalies are at work, what might be going on in terms of learning contingencies that could help explain why some people have difficulty engaging in this form of sensory behavior?

It will be easier to address this question if we are clear about the nature of the phenomenon. The traditional neurological perspective seems to start with the assumption that an impaired ability to form a mental image is the only problem to be explained. That is, what could be viewed as a behavioral deficit may instead be taken as no more than a neurological deficit. Giving the image problem strategic scientific priority leads to two tactical challenges, however. First, there is as yet no evidence that aphantasia should be defined by an inability to “form” mental images, or whatever is going on in the brain when we respond as if a physical stimulus is present when it is not. Anecdotal reports and survey findings tend to assume that when people say they cannot “see” an image of some sort there is no mental image to be “seen.” This assumption is guided by a culture that teaches us that the causes of behavior are primarily mental. From this perspective, it is the mental images that come first and then cause the behavioral reaction to them. However, the only direct evidence that there is such a phenomena as aphantasia is behavioral in nature. Some people say that they are not able to do something that most others say they can do. When this deficit is described in vernacular terms, it suggests a neurological shortcoming, but stripped of this everyday implication, all that is left is a verbal “report.”

A second challenge is that even though the possibility of a neurological malfunction is a reasonable hypothesis, the available understanding of how the brain “creates” sensory images in the absence of external stimulation is apparently pretty general, so identifying the specific way in which this process breaks down in aphantasia is going to be difficult. This is not a reason to avoid the neurological thesis, but trying to explain the phenomenon in a behavioral frame of reference may be a more parsimonious and approachable alternative. This contrasting strategy does not deny that there are neurological processes associated with “imagining” a sensation, merely that it may make scientific sense to use a solid understanding of the behavioral features of aphantasia to guide a search for possible neurological characteristics.

In sum, there are two general questions to be answered. One concerns the sources of control over the behavior of sensing stimuli that are not present. Learning how this behavior is acquired will presumably help explain variability in this skill, including factors that might interfere with its acquisition. The second question depends on what we learn in answering the first and pursues the neurological processes that may contribute to the phenomenon or even explain it entirely. Again, both research directions are reasonable, and a complete explanation will presumably require answers in both behavioral and neurological domains.

What might be going on behaviorally?

Before wondering about the behavioral aspects of aphantasia, we need to learn more about the behavior we are trying to explain. There are only two formal studies (Faw, 2009; Zeman et al, 2015), as well as one case report (Zeman et al, 2010). Most of what we know is in the form of responses to survey questions framed in colloquial terms, supplemented by personal descriptions from affected participants. The resulting evidence suggests that affected individuals share an apparent inability to engage in the behavior of sensing stimulation that is not otherwise immediately and directly present. However, this deficit is not uniform. These individuals collectively describe this limitation as varying in degree across sensory modalities, although vision is by far the most commonly affected modality. It is important to emphasize that participants have indicated that they do experience images in dreaming, however, and some experience involuntary “flashes” of imagery. Whatever may be going on with these individuals neurologically, it seems that it is possible for imaging in the absence of external stimuli to occur.

Aside from the matter in which sensory modalities are involved from one person to another, there is much to be learned about their sensory responding when direct stimulation is weak or absent. The reported evidence suggests that there is considerable variability in this kind of sensory responding in this population. What we learn about the details of this variability may influence our judgment about whether the “condition” is a narrow deficit or only one point on a continuum of competence in sensory responding. This information may also improve our ability to learn about its distribution in the general population. The survey by Faw (2009) of 2,500 participants suggests a prevalence of more than 2%. If this is true, then we all know people who live with this “problem” – if we wish to characterize it as such.

With a better understanding about the features of this form of sensory behavior, we will be in an improved position to study why might some individuals apparently fail to learn a skill most of us take for granted – the ability to seemingly “see” or “hear” events that are obviously not occurring. One possibility is that these individuals share a generalized learning disability that prevents them from learning this skill along with many others in the typical human repertoire. However, published reports don’t suggest that affected individuals are intellectually disabled by customary criteria, so we might put this possibility aside.

Of course, our definition of an ordinary repertoire allows for considerable variation from one person to another. Is what is being labeled as a relatively specific deficit not only more general than we now know, but also merely the result of normal variation in individual learning histories? What learning experiences are required to learn to respond as if sensory stimuli are present when they are not? Is this learning history deficient for some individuals? What deficiencies in contingencies might lead to this kind of behavioral deficit?

One of the most interesting behavioral questions is practical in nature. Can individuals who experience the deficits described here be taught to overcome them? The ability to design effective therapeutic teaching protocols might highlight the behavioral aspects of the phenomenon. Of course, an effective treatment would not eliminate the possibility that neurological anomalies also play a role in this condition. ABA interventions often overcome behavioral challenges that have clear biological underpinnings.

Finally, is it possible that other behavioral or neurological issues are associated with this deficit? For instance, an individual quoted in an article published on the website Science Daily (2015) said, “I have never been ambitious, and wondered if an inability to ‘imagine myself in a place ten years from now’ as a concrete image has affected this. I also find it difficult to jump from abstract thought to concrete examples, although I think a positive consequence is that I am perhaps better at thinking abstractly than many other people.” Does this statement suggest more going on than the side effects of a specific imaging deficit?

How we talk about behavior matters

This discussion of the phenomenon now labeled aphantasia should make clear the importance of the conceptual framework we bring to understanding human nature. The default approach to this phenomenon in both everyday and mainstream scientific culture is fundamentally mentalistic. Even the potentially viable neurological dimensions of the problem are filtered through a mentalistic perspective and dialect.

Radical behaviorism, together with our understanding of how behavior really works, allows a refreshing if not more more satisfying alternative. By avoiding the conceptual distractions and blind alleys encouraged by a mentalistic perspective and instead focusing on behavior as a strictly physical phenomenon, a scientific agenda emerges that takes advantage of the mature science of behavior analysis.


Faw, B. (2009). Conflicting intuitions may be based on differing abilities – evidence from mental imaging research. Journal of Consciousness Studies, 16, 45-68.

Skinner, B. F. (1953). Science and human behavior. New York: Free Press.

Zeman, A., Dewar, M., Dela Sala, S. Lives without imagery – Congenital aphantasia. Cortex, 2015; DOI: 10.1016/j.cortex.2015.05.019

Zeman, A. Z., Della Sala, S., Torrens, L. A., Gountouna, V. E., McGonigle, D. J., & Logie, R. H. (2010). Loss of imagery phenomenology with intact visuo-spatial task performance: a case of ‘blind imagination’. Neuropsychologia, 48, 145-155.

Zimmer, C. (2010). The Brain: Look deep into the mind’s eye. Discover, March Issue, 28-29.

University of Exeter. “Can’t count sheep? You could have aphantasia: Some people are born without the ability to visualize images.” ScienceDaily, 26 August 2015. .




  1. Eli Rector

    Wonderful read, Jim. Thank you.

    I had just written a much longer comment but something happened and it was erased!

    Oh well, I basically expressed amazement that so many people – scholars/thinkers – on this subject are so unaware of the basic principles and laws of behaviorism which explain so much of what they discuss. I’ve been interested my whole life in these subjects, but only after discovering ABA and radical behaviorism a few years ago did I feel like all the lights went on!

    A recent thought of mine is this: where is the line between a tact (or intraverbal), and the basic sensory experience all organisms have (pain, pleasure, smell, etc.). If I notice a blue ink stain on my finger, it only becomes a tact when I use verbal behavior in my head, no? I say to myself “my finger has a blue stain”. The intraverbal would be, “It must have been from a pen”. But could I not have these perceptions without the accompanied verbal behavior? Surely I could notice the stain as being something different. Stimulus equivalence would then associate it with pens, which I have learned are filled with ink and sometimes leak. Someone raised apart from a verbal community could have such thoughts.

    I wonder how complex the thoughts/stimulus equivalences could get before they are limited by a lack of verbal behavior? My guess is not far. I sometimes try to “notice” thoughts that I have that are not accompanied by verbal behavior. But it feels nearly impossible to tell. If only I could somehow record them!


    • Jim Johnston

      Thanks for your thoughtful question. I think the key to answering it lies in realizing that we tend to think about tacts a bit too narrowly. Much of our discussion of tacts seems to focus on the basics of their definition, especially in relation to other verbal response classes. In treatment scenarios, we are usually interested in teaching tacting skills – an interest that also focuses on their most basic features. We usually understand tacts as requiring a form of verbal behavior such as speaking or writing.

      When we perceive something – when we are aware of it – we are recognizing it in some way, even though we may not explicitly describe it to ourselves. If you see a blue ink stain on your finger, you won’t necessarily say to yourself, “That is an ink stain.” However, I would argue that the fact that you respond to the stimuli by seeing it as an ink stain is a form of tacting. The tact need not be verbal in the form of covert speech (thinking to yourself), but the fact that you see the ink stained finger as an ink stained finger is a form of description. Merely identifying it as such is tacting, even if you do not put even covert words to it. If you lacked a verbal repertoire, you would not recognize the ink stain or perceive it as such. You might respond to it in some way, but not with what we usually call perception or awareness. After all, we respond to stimuli all day long without being aware of them.

      Does this help?


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Jim Johnston

Dr. Johnston received his doctorate from the University of Florida in 1970 and held faculty positions at Georgia State University, the University of Florida, and Auburn University. He has published both laboratory and field research with both human and non-human species on a variety of topics. He has longstanding interests in the area of developmental disabilities and founded the Master’s Program in Applied Behavior Analysis in Developmental Disabilities at Auburn University. He has served as editor of The Behavior Analyst and on the editorial boards of the Journal of the Experimental Analysis of Behavior and the Journal of Applied Behavior Analysis, among others. He has served as president of the Association for Behavior Analysis International, as well as for the Florida, Alabama, and Southeastern behavior analysis organizations, and was the first president of the Behavior Analysis Certification Board and the Association of Professional Behavior Analysts.

Aphantasia November 2, 2015