Assessing aphantasia prevalence and the relation of self-reported imagery abilities and memory task performance

Assessing visual mental imagery abilities in cerebral visual impairment

Visual imagery refers to the ability to create voluntary mental representations in the absence of corresponding visual stimuli, and current evidence suggests that it shares common neural mechanisms with visual perception. Cerebral visual impairment (CVI) is a brain-based visual disorder caused by early neurological injury and maldevelopment of central visual processing pathways and areas. Individuals with CVI often present with a complex visual profile, including deficits related to higher-order visual processing. However, the impact of visual maldevelopment on imagery abilities in this population has not been extensively characterized. We used the Vividness of Visual Imagery Questionnaire (VVIQ) to investigate visual imagery abilities in a cohort of CVI participants (n = 25, mean age = 22.48 years ± 12.31 SD) compared to controls with neurotypical vision and development (n = 25, mean age = 22.88 years ± 4.94 SD). We found that individuals with CVI had significantly lower VVIQ scores (mean = 41.84 ± 18.61 SD) than controls (mean = 62.48 ± 13.07 SD), after controlling for age and verbal IQ level. Within the CVI group, visual imagery abilities were not significantly different when separated by baseline visual acuity, gestational status, or co-occurrence of autism spectrum disorder. These results suggest that impaired visual imagery may represent an important feature characterizing the complex visual profile of CVI.

"The Giant Black Elephant with white Tusks stood in a field of Green Grass": Cognitive and brain mechanisms underlying aphantasia

Aphantasia, a spectrum of inabilities creating and perceiving mental images, is becoming more of a focus in continued research to better understand functions of sensory perception and imagination. Current research on aphantasia is still in an era of exploration to find its underlying neural mechanisms, comorbidities and comparing levels of visual imagery to other cognitive functions. Through a systematic review, this article explores the most influential developments in aphantasia research. The search included 3 databases-PsycINFO, PubMed, and Web of Science. After a rigorous selection process, 52 studies are included in this review. The findings include new research themes across different studies such as relationships between aphantasia and diminished episodic and autobiographical memory, comorbidities including autism, attention, emotions, and neurobiological differences. By integrating diverse perspectives, this review aims to contribute to a deeper understanding of the cognitive processes underlying mental imagery and offers implications for further development in aphantasia research.

A Systematic Review of Aphantasia: Concept, Measurement, Neural Basis, and Theory Development

People with aphantasia exhibit the inability to voluntarily generate or form mental imagery in their minds. Since the term "aphantasia" was proposed to describe this, it has gained increasing attention from psychiatrists, neuroscientists, and clinicians. Previous studies have mainly focused on the definition, prevalence, and measurement of aphantasia, its impacts on individuals' cognitive and emotional processing, and theoretical frameworks synthesizing existing findings, which have contributed greatly to our understanding of aphantasia. However, there are still some debates regarding the conclusions derived from existing research and the theories that were constructed from various sources of evidence. Building upon existing endeavors, this systematic review emphasizes that future research is much needed to refine the definition and diagnosis of aphantasia, strengthen empirical investigations at behavioral and neural levels, and, more importantly, develop or update theories. These multiple lines of efforts could lead to a deeper understanding of aphantasia and further guide researchers in future research directions.

Phantasia, aphantasia, and hyperphantasia: Empirical data and conceptual considerations

Within the past decade, the term "phantasia" has been increasingly used to describe the human capacity, faculty, or power of visual mental imagery, with extremes of imagery vividness characterised as "aphantasia" and "hyperphantasia". A substantial volume of empirical research addressing these constructs has now been published, including attempts to find inductive correlates of behaviourally defined aphantasia, for example using research questionnaires and functional magnetic resonance imaging. Mental imagery has long been noted as a source of conceptual confusions but no specific conceptual analysis of the new formulation of phantasia, aphantasia, and hyperphantasia has been undertaken hitherto. We offer some conceptual considerations on phantasia, noting the ongoing confusion of perceptual with mental images, and the ubiquitous use of unvalidated subjective assessment instruments such as the Vividness of Visual Imagery Questionnaire (VVIQ) in diagnosis and assessment, development of which was predicated on these conceptual confusions. We offer some suggestions for a conceptual framework for future empirical studies in this field, circumventing these conceptual confusions.

Consciousness and sleep

Sleep is a universal, essential biological process. It is also an invaluable window on consciousness. It tells us that consciousness can be lost but also that it can be regained, in all its richness, when we are disconnected from the environment and unable to reflect. By considering the neurophysiological differences between dreaming and dreamless sleep, we can learn about the substrate of consciousness and understand why it vanishes. We also learn that the ongoing state of the substrate of consciousness determines the way each experience feels regardless of how it is triggered-endogenously or exogenously. Dreaming consciousness is also a window on sleep and its functions. Dreams tell us that the sleeping brain is remarkably lively, recombining intrinsic activation patterns from a vast repertoire, freed from the requirements of ongoing behavior and cognitive control.

Aphantasia and hyperphantasia: exploring imagery vividness extremes

The vividness of imagery varies between individuals. However, the existence of people in whom conscious, wakeful imagery is markedly reduced, or absent entirely, was neglected by psychology until the recent coinage of 'aphantasia' to describe this phenomenon. 'Hyperphantasia' denotes the converse - imagery whose vividness rivals perceptual experience. Around 1% and 3% of the population experience extreme aphantasia and hyperphantasia, respectively. Aphantasia runs in families, often affects imagery across several sense modalities, and is variably associated with reduced autobiographical memory, face recognition difficulty, and autism. Visual dreaming is often preserved. Subtypes of extreme imagery appear to be likely but are not yet well defined. Initial results suggest that alterations in connectivity between the frontoparietal and visual networks may provide the neural substrate for visual imagery extremes.

Properties of imagined experience across visual, auditory, and other sensory modalities

Little is known about the perceptual characteristics of mental images nor how they vary across sensory modalities. We conducted an exhaustive survey into how mental images are experienced across modalities, mainly targeting visual and auditory imagery of a single stimulus, the letter "O", to facilitate direct comparisons. We investigated temporal properties of mental images (e.g. onset latency, duration), spatial properties (e.g. apparent location), effort (e.g. ease, spontaneity, control), movement requirements (e.g. eye movements), real-imagined interactions (e.g. inner speech while reading), beliefs about imagery norms and terminologies, as well as respondent confidence. Participants also reported on the five traditional senses and their prominence during thinking, imagining, and dreaming. Overall, visual and auditory experiences dominated mental events, although auditory mental images were superior to visual mental images on almost every metric tested except regarding spatial properties. Our findings suggest that modality-specific differences in mental imagery may parallel those of other sensory neural processes.