Effects of Experimentally Induced Visual and Auditory Hallucinations on Cognitive and Emotional Functioning in Schizophrenia Patients and Healthy Individuals: The Modulatory Role of Placebo Intervention

Background: Schizophrenia is a complex neuropsychiatric disorder characterized by profound deficits in cognitive and emotional functioning, including altered perceptual experiences, heightened anxiety, amnesia, and impairments in episodic memory. While extensive research has examined naturalistic hallucinations, primarily through correlational approaches, experimental induction of hallucinations remains limited. The present study aimed to investigate the effects of experimentally induced visual and auditory hallucinations on cognitive and emotional functioning and to evaluate the efficacy of a placebo intervention in mitigating their impact in schizophrenia patients and healthy individuals. Method: A placebo-controlled, double-blind, mixed within- and between-group randomized block design was employed. Sixty participants (schizophrenia patients, n = 30; healthy controls, n = 30), aged 18–65 years, were recruited from multiple centers in Islamabad, Pakistan. Participants completed 10 experimental trials involving positive and negative visual and auditory hallucination induction using advanced PsychoPy software, alongside standardized assessments of cognitive and emotional processes. Results: Results revealed that schizophrenia patients exhibited heightened susceptibility to hallucination perception and increased anxiety during exposure to combined negative visual and auditory hallucinations relative to healthy controls. Negative hallucinations exacerbated amnesia and impaired episodic memory retrieval, whereas positive hallucinations facilitated cognitive performance. Importantly, the placebo intervention significantly attenuated the cognitive and emotional consequences of hallucinations, with more pronounced effects observed in schizophrenia patients. Conclusions: These findings highlight the potential therapeutic benefits of non-pharmacological interventions in schizophrenia and provide novel insights into the interaction between multisensory hallucinations and cognitive-emotional functioning. The study underscores the importance of developing individualized therapeutic strategies to address the complex clinical manifestations of schizophrenia across diverse healthcare settings.