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Introduction: Pareidolia, a form of visual illusions phenomenologically similar to complex visual hallucinations, is a phenomenon that is associated with visual hallucinations in dementia with Lewy bodies (DLB). This study aimed to identify commonalities and differences in behavioral and neural correlates between pareidolic illusions and visual hallucinations in DLB.
Methods: Forty-three patients with DLB underwent the scene pareidolia test, which evokes and measures pareidolic illusions, and standardized neuropsychological and behavioral assessments. Regional cerebral blood flow (rCBF) was measured by single-photon emission computed tomography. Factor analysis was performed to assess the relationships among pareidolic illusions, cognitive functions, and behavioral symptoms. Partial least squares correlation analysis was used to investigate the relationship between these symptoms and rCBF.
Results: Factor analysis yielded three behavior factors: the first factor (hallucinations/fluctuations) consisted of pareidolic illusions, visual hallucinations, and fluctuating cognition; the second factor (general cognitive function) consisted of general cognitive function and working memory; and the third factor (visual processing) consisted of visual processing and pareidolic illusions. Partial least squares correlation analysis identified two brain-behavior correlation patterns: (1) rCBF reduction in the frontal and perisylvian/periventricular regions was associated with lower general cognitive function and lower visual processing; and (2) rCBF reduction in the bilateral occipitotemporal cortex was associated with more severe hallucinations/fluctuations and lower visual processing.
Conclusions: At the behavioral level, pareidolic illusions are associated with visual hallucinations, fluctuating cognition, and visual processing in DLB. At the neural level, pareidolic illusions may arise from the synergistic effects of global neuropathological changes and occipitotemporal cortical dysfunctions.
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http://dx.doi.org/10.1016/j.parkreldis.2023.105513 | DOI Listing |
Int J Geriatr Psychiatry
September 2025
Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan.
Objectives: Pareidolic illusions involve perceiving meaningful objects in ambiguous or visually complex stimuli. Although seen in dementia, their presence and associated neuroanatomical basis in older adults without dementia remain unclear. Investigating these illusions in this population may reveal early neurodegenerative changes preceding overt dementia.
View Article and Find Full Text PDFBiomedicines
May 2025
Functional and Molecular Neuroimaging Unit, IRCCS Istituto delle Scienze Neurologiche di Bologna, 40139 Bologna, Italy.
Minor visual phenomena (MVP), such as visual illusions, pareidolias, feeling of presence, and passage hallucinations, are often experienced by patients with Lewy Body Disease (LBD), in addition to complex visual hallucinations (VH), even in the early stages of the disease. This systematic review aimed to provide an up-to-date literature review of the occurrence and prevalence of MVP in LBD and to assess their potential associations both with VH and visuoperceptual and visuospatial deficits. A systematic literature search was carried out in PubMed, Web of Science, APA PsycInfo, Scopus, and Cochrane Library, and a total of 44 articles were included.
View Article and Find Full Text PDFHeliyon
March 2024
Perception and Eye Movement Laboratory, Departments of Neurology and BioMedical Research, Inselspital, Bern University Hospital and University of Bern, Switzerland.
Pareidolia are perceptions of recognizable images or meaningful patterns where none exist. In recent years, this phenomenon has been increasingly studied in healthy subjects and patients with neurological or psychiatric diseases. The current study examined pareidolia production in a group of 53 stroke patients and 82 neurologically healthy controls who performed a natural images task.
View Article and Find Full Text PDFPLoS One
November 2023
Queensland Brain Institute, The University of Queensland, St Lucia, Queensland, Australia.
Pareidolias, or the misperception of ambiguous stimuli as meaningful objects, are complex visual illusions thought to be phenomenologically similar to Visual Hallucination (VH). VH are a major predictor of dementia in Parkinson's Disease (PD) and are included as a core clinical feature in Dementia with Lewy Bodies (DLB). A newly developed Noise Pareidolia Test (NPT) was proposed as a possible surrogate marker for VH in DLB patients as increased pareidolic responses correlated with informant-corroborated accounts of VH.
View Article and Find Full Text PDFParkinsonism Relat Disord
August 2023
Department of Behavioral Neurology and Cognitive Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Japan; Department of Behavioral Neurology and Neuropsychiatry, Osaka UniversityUnited Graduate School of Child Development, Suita, Japan; Department of Psychiatry, Osaka University
Introduction: Pareidolia, a form of visual illusions phenomenologically similar to complex visual hallucinations, is a phenomenon that is associated with visual hallucinations in dementia with Lewy bodies (DLB). This study aimed to identify commonalities and differences in behavioral and neural correlates between pareidolic illusions and visual hallucinations in DLB.
Methods: Forty-three patients with DLB underwent the scene pareidolia test, which evokes and measures pareidolic illusions, and standardized neuropsychological and behavioral assessments.