Spatial transformation in mental rotation tasks in aphantasia.

Aphantasia refers to the inability to summon images to one's own mind's eye, resulting in selective deficits of voluntary object imagery. In the present study, we investigated whether M. X., a case of acquired aphantasia, can still retain some form of spatial transformation processes even though he is unable to subjectively experience voluntary object imagery. M. X. and a group of control participants were asked to complete a letter mental rotation task (MRT), typically used to assess the nature of the spatial transformation, while behavioural and electrophysiological responses were recorded. M. X. was able to complete the MRTs as accurately as controls, showing the pattern of increasing RTs as a function of rotation angle typical of MRTs. However, event-related potential (ERP) results showed systematic differences between M. X. and controls. On canonical letter trials, the rotation-related negativity (RRN), an ERP component considered as the psychophysiological correlate of the spatial transformation of mental rotation (MR), was present in both M. X. and controls and similarly modulated by rotation angle. However, no such modulation was observed for M. X. on mirror-reversed letter trials. These findings suggest that, at least under specific experimental conditions, the inability to create a depictive representation of the stimuli does not prevent the engagement of spatial transformation in aphantasia. However, the ability to apply spatial transformation varies with tasks and might be accounted for by the specific type of mental representation that can be accessed.

Aphantasia, dysikonesia, anauralia: call for a single term for the lack of mental imagery-Commentary on Dance et al. (2021) and Hinwar and Lambert (2021).

Recently, the term 'aphantasia' has become current in scientific and public discourse to denote the absence of mental imagery. However, new terms for aphantasia or its subgroups have recently been proposed, e.g., 'dysikonesia' or 'anauralia', which complicates the literature, research communication and understanding for the general public. Before further terms emerge, we advocate the consistent use of the term 'aphantasia' as it can be used flexibly and precisely, and is already widely known in the scientific community and among the general public.

Behavioral and Neural Signatures of Visual Imagery Vividness Extremes: Aphantasia versus Hyperphantasia.

Although Galton recognized in the 1880s that some individuals lack visual imagery, this phenomenon was mostly neglected over the following century. We recently coined the terms "aphantasia" and "hyperphantasia" to describe visual imagery vividness extremes, unlocking a sustained surge of public interest. Aphantasia is associated with subjective impairment of face recognition and autobiographical memory. Here we report the first systematic, wide-ranging neuropsychological and brain imaging study of people with aphantasia (n = 24), hyperphantasia (n = 25), and midrange imagery vividness (n = 20). Despite equivalent performance on standard memory tests, marked group differences were measured in autobiographical memory and imagination, participants with hyperphantasia outperforming controls who outperformed participants with aphantasia. Face recognition difficulties and autistic spectrum traits were reported more commonly in aphantasia. The Revised NEO Personality Inventory highlighted reduced extraversion in the aphantasia group and increased openness in the hyperphantasia group. Resting state fMRI revealed stronger connectivity between prefrontal cortices and the visual network among hyperphantasic than aphantasic participants. In an active fMRI paradigm, there was greater anterior parietal activation among hyperphantasic and control than aphantasic participants when comparing visualization of famous faces and places with perception. These behavioral and neural signatures of visual imagery vividness extremes validate and illuminate this significant but neglected dimension of individual difference.

Aphantasia: The science of visual imagery extremes.

Visual imagery allows us to revisit the appearance of things in their absence and to test out virtual combinations of sensory experience. Visual imagery has been linked to many cognitive processes, such as autobiographical and visual working memory. Imagery also plays symptomatic and mechanistic roles in neurologic and mental disorders and is utilized in treatment. A large network of brain activity spanning frontal, parietal, temporal, and visual cortex is involved in generating and maintain images in mind. The ability to visualize has extreme variations, ranging from completely absent (aphantasia) to photo-like (hyperphantasia). The anatomy and functionality of visual cortex, including primary visual cortex, have been associated with individual differences in visual imagery ability, pointing to a potential correlate for both aphantasia and hyperphantasia. Preliminary evidence suggests that lifelong aphantasia is associated with prosopagnosia and reduction in autobiographical memory; hyperphantasia is associated with synesthesia. Aphantasic individuals can also be highly imaginative and are able to complete many tasks that were previously thought to rely on visual imagery, demonstrating that visualization is only one of many ways of representing things in their absence. The study of extreme imagination reminds us how easily invisible differences can escape detection.

Phantasia-The psychological significance of lifelong visual imagery vividness extremes.

Visual imagery typically enables us to see absent items in the mind's eye. It plays a role in memory, day-dreaming and creativity. Since coining the terms aphantasia and hyperphantasia to describe the absence and abundance of visual imagery, we have been contacted by many thousands of people with extreme imagery abilities. Questionnaire data from 2000 participants with aphantasia and 200 with hyperphantasia indicate that aphantasia is associated with scientific and mathematical occupations, whereas hyperphantasia is associated with 'creative' professions. Participants with aphantasia report an elevated rate of difficulty with face recognition and autobiographical memory, whereas participants with hyperphantasia report an elevated rate of synaesthesia. Around half those with aphantasia describe an absence of wakeful imagery in all sense modalities, while a majority dream visually. Aphantasia appears to run within families more often than would be expected by chance. Aphantasia and hyperphantasia appear to be widespread but neglected features of human experience with informative psychological associations.

The neural correlates of visual imagery vividness - An fMRI study and literature review.

Using the Vividness of Visual Imagery Questionnaire we selected 14 high-scoring and 15 low-scoring healthy participants from an initial sample of 111 undergraduates. The two groups were matched on measures of age, IQ, memory and mood but differed significantly in imagery vividness. We used fMRI to examine brain activation while participants looked at, or later imagined, famous faces and famous buildings. Group comparison revealed that the low-vividness group activated a more widespread set of brain regions while visualising than the high-vividness group. Parametric analysis of brain activation in relation to imagery vividness across the entire group of participants revealed distinct patterns of positive and negative correlation. In particular, several posterior cortical regions show a positive correlation with imagery vividness: regions of the fusiform gyrus, posterior cingulate and parahippocampal gyri (BAs 19, 29, 31 and 36) displayed exclusively positive correlations. By contrast several frontal regions including parts of anterior cingulate cortex (BA 24) and inferior frontal gyrus (BAs 44 and 47), as well as the insula (BA 13), auditory cortex (BA 41) and early visual cortices (BAs 17 and 18) displayed exclusively negative correlations. We discuss these results in relation to a previous, functional imaging study of a clinical case of 'blind imagination', and to the existing literature on the functional imaging correlates of imagery vividness and related phenomena in visual and other domains.

On Picturing a Candle: The Prehistory of Imagery Science.

The past 25 years have seen a rapid growth of knowledge about brain mechanisms involved in visual mental imagery. These advances have largely been made independently of the long history of philosophical - and even psychological - reckoning with imagery and its parent concept 'imagination'. We suggest that the view from these empirical findings can be widened by an appreciation of imagination's intellectual history, and we seek to show how that history both created the conditions for - and presents challenges to - the scientific endeavor. We focus on the neuroscientific literature's most commonly used task - imagining a concrete object - and, after sketching what is known of the neurobiological mechanisms involved, we examine the same basic act of imagining from the perspective of several key positions in the history of philosophy and psychology. We present positions that, firstly, contextualize and inform the neuroscientific account, and secondly, pose conceptual and methodological challenges to the scientific analysis of imagery. We conclude by reflecting on the intellectual history of visualization in the light of contemporary science, and the extent to which such science may resolve long-standing theoretical debates.

Accelerated long-term forgetting in transient epileptic amnesia: an acquisition or consolidation deficit?

Accelerated Long-term Forgetting (ALF) is the rapid loss of newly acquired memories over days to weeks despite normal retention at standard (~30 min) intervals. It has recently been described in association with epilepsy, particularly the syndrome of Transient Epileptic Amnesia (TEA). The cognitive mechanisms underlying ALF remain uncertain, but disruption either of memory acquisition or consolidation processes has been postulated. To arbitrate between these accounts, we reanalysed data from an existing word-list recall data set to investigate whether ALF can be observed for words learned under precisely matched conditions in TEA patients and controls. We reanalysed the data of 24 patients with TEA and 24 matched healthy controls who learnt a 15-item word list to a learning criterion of 90% with a minimum of five learning trials. Free recall of the words was probed at delays of 30 min and 1 week and 3 weeks after learning. In addition, a 'yes-no' recognition test was conducted after the 3-week free recall. Forgetting rates across the first 30 min delay and the subsequent 1 week and 3 week delay were compared between patients and controls. To ensure that learning conditions were closely matched between patients and control participants, we excluded exceptionally fast (N(TEA)=1, N(controls)=4) and slow (N(TEA)=6, N(controls)=2) learners. Furthermore, we analysed only words that were presented five or six times during learning and retrieved successfully on four or five occasions during learning. Recall performance on the last learning trial and 30 min after acquisition were indistinguishable between TEA patients and controls. Over the delay interval of 30 min to 1 week, however, accelerated forgetting of this newly learned verbal material was observed in TEA patients. This severe forgetting is also reflected in the three-week recognition test, where TEA patients performed significantly worse than controls. Moreover, whereas recall on the last learning trial correlated significantly with the 30 min delayed recall in both groups, recall on the last learning trial correlated significantly with 1 week and 3 week delayed recall only in the controls. In both groups, the three-week free recall performance correlated with the three-week recognition test. Patients with TEA demonstrate ALF even for verbal material that is learned under precisely matched conditions. These results are consistent with the hypothesis that ALF represents a disruption of memory consolidation rather than an acquisition deficit.

Imagining the present: amnesia may impair descriptions of the present as well as of the future and the past.

Recent evidence suggests that in some patients with amnesia the capacity to imagine the future is impaired in parallel with the capacity to remember the past. This paper asks whether descriptions of the present may be similarly affected. We recruited 7 patients with amnesic syndromes of varying aetiologies who were matched for age, sex and education with 7 control participants. Patients showed no deficits on subjective measures of visual imagery. They were impaired by comparison with controls on measures of imagination and future thinking. However there was an even more marked impairment on tasks requiring them to give descriptions of their current experience. Potential explanations include effects of amnesia on narrative construction or on the texture of experience itself, and the confounding influence of cognitive impairments outside the memory domain. We conclude that tasks requiring descriptions of current experience provide a valuable control condition in studies examining the relationship between memory and imagination.

Loss of imagery phenomenology with intact visuo-spatial task performance: a case of 'blind imagination'.

The capacity for imagery, enabling us to visualise absent items and events, is a ubiquitous feature of our experience. This paper describes the case of a patient, MX, who abruptly lost the ability to generate visual images. He rated himself as experiencing almost no imagery on standard questionnaires, yet performed normally on standard tests of perception, visual imagery and visual memory. These unexpected findings were explored using functional MRI scanning (fMRI). Activation patterns while viewing famous faces were not significantly different between MX and controls, including expected activity in the fusiform gyrus. However, during attempted imagery, activation in MX's brain was significantly reduced in a network of posterior regions while activity in frontal regions was increased compared to controls. These findings are interpreted as suggesting that MX adopted a different cognitive strategy from controls when performing the imagery task. Evidence from experimental tasks thought to rely on mental imagery, such as the Brooks' matrices and mental rotation, support this interpretation. Taken together, these results indicate that successful performance in visual imagery and visual memory tasks can be dissociated from the phenomenal experience of visual imagery.