aphantasia

Aphantasia (/ˌeɪfænˈteɪʒə/ ay-fan-TAY-zhə, /ˌæfænˈteɪʒə/ a-fan-TAY-zhə) is the inability to voluntarily create mental images in one's mind.^[1]

The phenomenon was first described by Francis Galton in 1880^[2] but has since remained relatively unstudied. Interest in the phenomenon renewed after the publication of a study in 2015 conducted by a team led by Professor Adam Zeman of the University of Exeter.^[3] Zeman's team coined the term aphantasia,^[4] derived from the ancient Greek word phantasia (φᾰντᾰσῐ́ᾱ), which means "imagination", and the prefix a- (ᾰ̓-), which means "without".^[5]

Research on the condition is still scarce.^[6][7] Hyperphantasia, the condition of having extremely vivid mental imagery, is the opposite of aphantasia.^[8]

HistoryEdit

The phenomenon was first described by Francis Galton in 1880 in a statistical study about mental imagery.^[2] Galton found it was a common phenomenon among his peers. He wrote:

To my astonishment, I found that the great majority of the men of science to whom I first applied, protested that mental imagery was unknown to them, and they looked on me as fanciful and fantastic in supposing that the words 'mental imagery' really expressed what I believed everybody supposed them to mean. They had no more notion of its true nature than a colour-blind man who has not discerned his defect has of the nature of colour.^[2]

In 1897, Théodule-Armand Ribot reported a kind of "typographic visual type" imagination, consisting in mentally seeing ideas in the form of corresponding printed words.^[9] As paraphrased by Jacques Hadamard,

The first discovery of this by Ribot was the case of a man whom he mentions as a well-known physiologist. For that man, even the words "dog, animal" (while he was living among dogs and experimenting on them daily) were not accompanied by any image, but were seen by him as being printed. Similarly, when he heard the name of an intimate friend, he saw it printed and had to make an effort to see the image of this friend... Moreover, according to Ribot, men belonging to the typographic-visual type cannot conceive how other people's thought can proceed differently.^[10]

The phenomenon remained largely unstudied until 2005, when Professor Adam Zeman of the University of Exeter was approached by a man who seemed to have lost the ability to visualize after undergoing minor surgery.^[11] Following the publication of this patient's case in 2010,^[12] a number of people approached Zeman reporting a lifelong inability to visualize. In 2015, Zeman's team published a paper on what they termed "congenital aphantasia",^[3] sparking renewed interest in the phenomenon.^[4]

ResearchEdit

Zeman's 2015 paper used the Vividness of Visual Imagery Questionnaire (VVIQ), developed by David Marks in 1973, to evaluate the quality of the mental image of 21 self-diagnosed and self-selected participants. He identified that aphantasics lack voluntary visualizations only; they are still able to have involuntary visualizations such as dreams.^[3]

In 2017, a paper published by Rebecca Keogh and Joel Pearson, researchers at University of New South Wales, measured the sensory capacity of mental imagery using binocular-rivalry (BR) and imagery-based priming and found that when asked to imagine a stimulus, the self-reported aphantasics experienced almost no perceptual priming, compared to those who reported higher imagery scores where perceptual priming had an effect.^[13] In 2020, Keogh and Pearson published another paper illustrating measurable differences correlated with visual imagery, this time by indirectly measuring cortical excitability in the primary visual cortex (V1).^[14]

A 2020 study concluded that those who experience aphantasia also experience reduced imagery in other senses, and have less vivid autobiographical memories.^[15]

In 2021, a study that measured the perspiration (via skin conductance levels) of participants in response to reading a frightening story and then viewing fear-inducing images found that participants with aphantasia, but not the general population, experienced a flat-line physiological response during the reading experiment, but found no difference in physiological responses between the groups when participants viewed fear-inducing images. The study concluded the evidence supported the emotional amplification theory of visual imagery.^[16]

The same year, a study relating aphantasia, synesthesia, and autism was published, pinpointing that aphantasics reported more autistic traits than controls, with weaknesses in imagination and social skills.^[17]

In addition to congenital aphantasia, there have been cases reported of acquired aphantasia, due either to brain injury or psychological causes.^[18][19]

A 2022 study estimated the prevalence of aphantasia among the general population by screening undergraduate students and people from an online crowdsourcing marketplace through the Vividness of Visual Imagery Questionnaire. They found that 0.8% of the population was unable to form visual mental images, and 3.9% of the population was either unable to form mental images or had dim or vague mental imagery.^[20] Sitek and Konieczna have shown that its progressive form may be a harbinger of dementia.^[21] A group of authors interviewed aphantasics about their lives and found that they generated fewer episodic details than controls for both past and future events, indicating that visual imagery is an important cognitive tool for dynamic retrieval and recombination of episodic details.^[22]

There have been various approaches to find a general theory of aphantasia or incorporate it into current philosophical, psychological and linguistic research. Blomkvist^[23] has suggested that aphantasia is best explained as a malfunction of processes in the episodic system and sees it as an episodic system condition. Aphantasia also has been studied from philosophical perspectives. Šekrst^[24] proposed that a gradual range of perceptions and mental images, from aphantasia to hyperphantasia, influences philosophical analysis of mental imagery from a fuzzy standpoint, along with influence on linguistics and semiotics. Whiteley^[25] argues that a modified theory of dreaming has to incorporate aphantasia, by involving the claim that dreams are a non-voluntary form of imagination.