Visual Information Processing in Schizophrenia Patients With Visual Hallucinations

Not Applicable

• Conditions: Auditory Hallucination; Schizophrenia; Visual Hallucination; False Perception

• Registration Number: NCT03188133
• Lead Sponsor: Central Hospital, Nancy, France

Brief Summary

Occurrence of visual hallucinations (VHs) in schizophrenia depend in part on disorders in the processing of late visual information (Top-Down). The broader question of how these top-down mechanisms (cognitive and / or emotional mechanisms) are involved in the occurrence of VHs remains to be specified and very few behavioral studies have so far been interested. The investigators propose to study the implication of Top-Down mechanisms in the visual hallucinatory manifestations, more specifically in the processing of ambiguous stimuli during an emotional priming task. Schizophrenia patients with VHs would have more false visual perceptions in the treatment of ambiguous stimuli than schizophrenia patients with auditory hallucinations or no hallucinations (AH/NH) and healthy controls.

Detailed Description

In schizophrenia patients with auditory hallucinations, top-down mechanism on perceptual processing could be illustrated by tasks of listening to white noise. These studies show that psychotic subjects detect more words and phrases when exposed to these stimuli. In schizophrenia patients with VHs, to our knowledge no study have explored the mechanism of false perception. Thus, we propose to experimentally manipulate the implication of Top-Down mechanisms on visual perception using an emotional priming task. This paradigm has already been used in this population to explain the mechanisms underlying productive symptoms. For example, in an emotional priming task authors have shown that a negative valence primer contributes to the implementation of an interpretive bias in a confidence judgment task.

The aim of the present study is to explore the implication of these Top-Down mechanisms in hallucinatory manifestations, more specifically on the treatment of ambiguous visual stimuli during an emotional priming task by manipulating the emotional valence of the primer. The goal is to determine how emotional environmental elements contribute to the formation of erroneous perceptions in patients with schizophrenia with VHs.

Study Timeline

• Study First Submitted: 2017-06-09
• Study First Submitted QC: 2017-06-14
• Study First Posted: 2017-06-15
• Status Verified: 2017-10
• Last Update Submitted: 2017-10-06
• Last Update Posted: 2017-10-09
• Study Start: 2017-10-17
• Primary Completion: 2018-05-01
• Study Completion: 2020-10-31

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 90

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Number of false visual perception on the emotional priming task	through study completion an average of 6 months	Number of false perception made by participants on an ambiguous visual stimulus i.e when a participant identifies incorrectly an ambiguous stimulus as a genuine percept (for example a participant sees a face in a noisy grey pattern)

Secondary Outcome Measures

Name	Time	Method
Cognitive performances at the neuropsychological assessment	through study completion an average of 6 months	Cognitive performances at the neuropsychological assessment conducted for both groups of schizophrenia patients. Neuropsychological assessment will provide performance scores on different cognitive functions : episodic memory (California Verbal Learning Test), visual memory (delayed match to sample task), working memory (forward and backward digit span, n-back task), sustained attention (test of attentional performance battery), divided attention (test of attentional performance battery), inhibition (test of attentional performance battery), processing speed (coding) and visual perception and processing (visual object space perception task).
Psychosensory hallucinations scale scores	through study completion an average of 6 months	scores on the Psychosensory hallucinations scale conducted for both schizophrenia patients groups. This scale provides a complete evaluation of hallucinations in all modalities as well as the impact of these symptoms on daily life.
number of false visual perception on the emotional priming task depending of the emotional valence manipulated	through study completion an average of 6 months	The investigators will investigate if the manipulated valence of the emotional priming task influences the number of false visual perceptions of ambiguous stimuli