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Deciphering Functional Hallucinations – Insights from Three Patients with Schizophrenia

Shruti Garg, Niharika Malhotra, Preeti Singh

Annals of Indian Psychiatry May 18, 2026 DOI: 10.4103/aip.aip_244_25 (opens in new tab)

Study at a glance

AI-extracted from the abstract
Characteristics Case study Case report Peer reviewed
Sample size 3
Population People with schizophrenia
Key findings The authors describe three cases of functional hallucinations in schizophrenia, involving auditory and visual modalities, in which hallucinations are consistently triggered by a specific real external stimulus. They argue that this phenomenology requires careful assessment to distinguish it from other perceptual abnormalities and that further research is needed on its neurobiological basis and long-term prognosis.

Abstract

Abstract Hallucinations may involve any of the sensory modalities – auditory, visual, tactile, olfactory, and gustatory and may present in mixed or complex perceptual hallucinations. Among the rarer forms of hallucinations are functional hallucinations. Functional hallucinations are a rare and understudied phenomenon in which hallucinations are consistently triggered by a specific real external stimulus, typically within the same sensory modality. We describe three cases of functional hallucinations in schizophrenia, involving auditory and visual modality. This unique phenomenology requires careful assessment to differentiate it from other types of perceptual abnormalities. Further research is needed to understand their neurobiological basis and long-term prognosis.