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Introduction

Francis Galton first noted the variation in voluntary visual imagery during a "breakfast table survey" accounted in his 1880 paper. A case of trauma induced complete lack of visual imagery was noted in 1883 by Charcot linked to a possible cerebral lesion, other similar cases have been noted. Little interest was shown in the subject until the publication of an article by Zeman et al in 2010 noting the loss of voluntary visual imagery, possibly following angioplasty, of MX. Following reporting of this article in the magazine Discover a number of people contacted Zeman to report they had no visual imagery, however these people claimed to have had none since birth, leading to the publication in 2015 of Zeman's paper describing "congenital aphantasia" a term coined by Zeman to describe the condition of lack of voluntary visual imagery. Faw, in a survey of 2500 individuals, reports that 2.1 - 2.7% of people report a lack of voluntary visual imagery.

History

Aristotle called mental images "phantasma" and described it as the only way the blind can perceive images, the majority of work on mental imagery has been on strong imagers or people retaining mental imagery after suffering blindness, Galton's work being an exception, his initial breakfast survey was followed by a survey of 100 learned men where he found that, although not as prevalent as first thought, a significant number, 6, described having no mental imagery. Visual imagery was claimed by behaviourists to be symbolic, John B. Watson describing it as "sheer bunk", however recent studies have shown that mental imagery can be measured and is depictive/pictorial. Instances of aphantasia due to trauma, emotional and physical, have been noted, but interest in the subject soon declined, it being considered of little or no interest until Zeman's 2010 paper.

Research

In 2010 Zeman published his paper about MX and its reporting in the magazine Discover led to the author being contacted by people with the same condition, although this time without severe brain trauma or injury, these people described how they had no mental imagery or little mental imagery from birth, these 21 people became the subject of Zeman's 2015 research. They were tested using the Vividness of Visual Imagery Questionnaire (VVIQ) and found to have either substantial (9) or complete (12) lack of voluntary visual imagery, Zeman coining the term "congenital aphantasia" for the condition. Press interest in the condition e.g. The Guardian and Discover has led to the appearance of online blogs including that of Blake Ross and community groups and forums for people with the condition to discuss their experiences e.g. http://aphant.asia/. Interestingly the majority of aphantasiacs have dream imagery, although they have difficulty in recalling their dreams, this may result from processing differences in dream imagery and voluntary mental imagery, dream imagery being produced "from below" by brainstem activity and voluntary imagery involving the fronto-parietal cortical executive system.

Whilst the majority recognise aphantasia as having an organic root, some have postulated that the condition may be psychogenic in occurence, this was refuted by Zeman and differences in processing by high and low imagers seem to agree with him. Research has also shown that self-referred aphantasiacs do have organic differences in processing, using the technique of binocular rivalry it was shown that aphantasiacs had a significant reduction in priming over the control group, the aphantasiacs scoring close to chance.

As early as 1909, visual imagery had been further subdivided into voluntary imagery; when the subject produces visual images at will and spontaneous imagery; where imagery forms part of the normal function of mental processes, questioning whether Galton had Zeman coined the term aphantasia to denote the absence of voluntary imagery only , in a further refinment, the lack of spontaneous and voluntary imagery has been referred to as total aphantasia.

Links to SDAM

Cases of debilitating deficits in autobiographical memory following injury or disease have often been reported e.g. Kapur 1999 along with episodic memory deficiencies in children resulting from damage to the hippocampus due to foetal anoxia .Recently reports of otherwise normally functioning people with severely impaired episodic memory have come to light, this syndrome has been named Severely Deficient Autobiographical Memory (SDAM), these people are able to learn semantic information about an event, can even describe them but are unable to relive past events, interestingly they present no history of brain injury or evidence of it in neuroimaging. SDAM individuals have been shown to not engage autobiographical networks when given appropriate controls, showing fewer episodic details in more remote events, this linked with other reductions in phenomenological sense of recollection point to SDAM being a result of faulty encoding ; individuals with SDAM also show reduced activation of the precuneus and medial prefrontal cortex. Links have been made between this condition and aphantasia, with Watkins proposing that SDAM occurs only in people with total aphantasia, this has yet to be proven although a search of blogs and forums has yet to find a case of SDAM not accompanied by total aphantasia, although further research is needed on this matter and aphantasia as a whole.

Aphantasia in Popular Culture

Along with Blake Ross' Facebook blog mentioned earlier aphantasia has formed the theme of a song by the Canadian band Mecca Normal, the book Lying in Bed by J.D.Landis which has a character with aphantasia and the recently published Aphantasia: Experiences, Perceptions, and Insights by Alan Kendle which has a foreword by Adam Zeman. Amongst high profile aphantasiacs are the geneticist Craig Venter and neuroscientist and author Oliver Sacks, see the book Minds Eye for a more comprehensive description of his aphantasia.

References