Running Head: APHANTASIA 1 Investigation into Aphantasia: Neurological, Functional, and Behavioral Correlates Olivia F. Tween Beloit College APHANTASIA 2 Investigation into Aphantasia: The Neurological, Functional, and Behavioral Correlates Introduction: Seeing With Your Mind’s Eye? For many people, imagining calm waves rolling onto a white, sandy beach on a clear and sunny day is an easy way to relax or meditate. They may take solace in picturing the faces of their loved ones when they feel homesick, or pass the time daydreaming elaborate fantasy scenes of dogs on motorcycles. While some may take this ability for granted, there are many people in the world who cannot picture themselves relaxing on a beach, or the faces of the closest friends, or a fantastic and impossible daydream; they see only darkness when they close their eyes. These people have aphantasia, a term coined by Zeman, Dewar, and Della Sala (2015) to describe “a condition of reduced or absent voluntary imagery.” Historical Overview: 1880 to 2018 This phenomenon has been present throughout historical research on mental imagery. Francis Galton is widely credited with having first documented the inability to produce and experience visual mental imagery. As an early eugenicist, many of his claims are problematic, although the first-hand statements published by Galton (1880) provide valuable accounts on variations in mental imagery. Galton published qualitative reports of the vividness of participants’ mental imagery, regarding the illumination, definition, and coloring of a mental image of their breakfast table. Participants described their subjective perception of the vividness and detail of their mental images, with reports ranging from perfectly clear and vivid to extremely reduced or nonexistent. Some participants reported seeing mental pictures that were as bright, colorful, and clear as the real table. Others could easily recall and describe the table and specific details of the scene, but had little or no ability to imagine it visually. One APHANTASIA 3 participant reported that his image was, “dim and indistinct, yet I can give an account of this morning’s breakfast table… but my imagination is seldom pictorial except between sleeping and waking,” (Galton, 1880, p. 4). Since being given a name in 2015, aphantasia has become more well-known and has been popularized online and in the media. This phenomenon has also caught the attention of visual imagery researchers. As information on aphantasia becomes more widely available, more people are discovering that they also are unable to conjure mental images, while other people can genuinely visualize objects, places, faces, and memories within their mind’s eye. This discovery has led many people to study and share their experiences with aphantasia by creating groups on social media platforms and publishing articles on their personal experiences. There is even a book titled, Aphantasia: Experiences, Perceptions, and Insights, which features first-hand ​ ​ accounts from aphants on their perspectives of living with aphantasia (Kendle, 2017). The Eye’s Mind research project, led by Adam Zeman, was established shortly after Zeman et al. (2015) coined the term aphantasia. Since first defining the term, the Eye’s Mind has gathered survey data from roughly 11,000 participants with a variety of mental imaging abilities and conducted many studies on aphantasia (e.g., Zeman, MacKisack, & Onians, 2018). The Eye’s Mind project is not only focused on aphantasia, but is concerned with a variety of aspects of visualization. One of its primary goals is to determine the neurological correlates of mental imagery and visualization through a meta-analysis of functional imaging research. The Eye’s Mind project also examines individual variations in mental imaging ability, focusing specifically on the extreme ends of the spectrum: both aphantasia and hyperphantasia (a APHANTASIA 4 heightened ability of voluntary visual imagery), as well as related conditions such as severely deficient autobiographical memory (SDAM) and synaesthesia. In this paper I will conduct a thorough examination and organization of available research on aphantasia. The articles and books I consulted while researching this condition led me to organize the information in a way similar to the Eye’s Mind study, as outlined in Zeman et al.’s report (2018). I will examine two theories of the known types of aphantasia, as well as the neurological correlates associated with a range of mental imagery ability, and the functional and behavioral correlates of aphantasia and low imaging ability. I will then consider published accounts of the effects of hallucinogenic drugs on the visualization abilities of people with aphantasia and review popular strategies for coping with and treating aphantasia. I will end by discussing related disorders and other extreme mental imaging phenomena, providing my own opinion on existing research, and suggesting possible future research about aphantasia. Types of Aphantasia There are two main types of aphantasia: congenital and acquired. Congenital aphantasia, as the name suggests, is the lack of mental imagery from birth that persists throughout one’s lifetime. Acquired aphantasia, on the other hand, is categorized by a sudden loss of voluntary mental images in those who previously possessed the ability to produce them. Congenital Aphantasia Congenital aphantasia was first studied in Zeman et al.’s (2015) groundbreaking study. They initially tested 21 participants with congenital aphantasia, who reported a consistent lack of voluntary visual imagery throughout life. Participants took the Vividness of Visual Imagery Questionnaire (VVIQ), which measures the clarity and vividness of mental images of faces, APHANTASIA 5 objects, and locations, as well as another questionnaire about the aphant’s personal experiences with aphantasia. All participants received a VVIQ score indicating a “substantial (9/21) or complete (12/21) deficit in voluntary visual imagery,” (Zeman et al., 2015, pg. 3). Many participants reported involuntary images occurring as “flashes” (10/21) while awake or experienced while dreaming (17/21). All of the participants described their lack of voluntary imagery as a persistent, lifelong state. Acquired Aphantasia The participants of the study discussed above reached out to Zeman et al. (2015) after learning about a prior study conducted by Zeman, et al. (2010), in which participant MX was compared to a control group on a variety of visual imagery, psychometric, and neuroimaging tests. MX reported a total loss of voluntary and spontaneous visual imagery following a coronary angioplasty. Unlike the participants of Zeman et al.’s (2015) study on congenital aphantasia, MX had previously possessed the ability to voluntarily imagine visual mental images. Aside from losing his ability to visualize, MX developed no other cognitive impairments following his surgery. Despite self-reporting that he experienced no mental imagery, MX performed normally on multiple tests of visual imagery and visual memory. Potential Causes: Neurological vs. Psychological Basis of Aphantasia In their study on congenital aphantasia, Zeman et al. (2015) suggested that this type of aphantasia may have neuropsychological correlates, much like other conditions such as synaesthesia and congenital prosopagnosia. In response to Zeman et al., de Vito and Bartolomeo (2015) argued that aphantasia may have a psychological component, and could be a symptom of depressive states, anxiety, or dissociative disorders. While it is possible that some manifestations APHANTASIA 6 of aphantasia could be caused or exacerbated by certain psychological disorders, research has shown that both congenital and acquired aphantasia have neurological correlates, and the brain areas activated by aphants during visual imagery tests are different from those activated in individuals with higher levels of imaging ability. Neurological Correlates Fulford et al. (2018) conducted an fMRI study on participants with both low and high levels of visual imaging abilities to determine which brain areas are activated in aphants during tests which typically involve mental imagery. They found that participants with higher levels of visual imagery ability had activation in areas of the brain that were distinctly different, and much less widespread, than the areas activated in participants with aphantasia. Tables 1 and 2 summarize the findings of Fulford et al. and organize the information on the brain areas involved with mental imagery for individuals with aphantasia or low imaging abilities and the non-aphant control participants, and an overview of which areas have increased and decreased activation for both groups during tests of mental imagery. As noted by Fulford et al., there is still some disagreement on how to label and separate different brain areas within the field of neuroscience research. Case Studies MX Before creating the term “aphantasia,” Zeman et al. (2010) were studying neurological differences in people who claimed to lack the ability to produce mental images. The study on MX, an acquired aphant who performed similarly to controls on standard tests of visual imagery ability, cemented the existence and validity of this condition, and led to the founding of the Eye’s APHANTASIA 7 Mind study. Functional MRI and Blood Oxygenation Level-Dependent (BOLD) imaging tests showed that while the same brain areas were activated in both MX and the control participants when physically perceiving an