Neural Account of Social Placebo Effect

NCT ID: NCT03891459

Last Updated: 2019-03-27

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 68 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2018-06-27
• Study Completion Date: 2018-11-05

Brief Summary

The current study aimed to reveal the neural mechanism of social placebo belief formation and belief representation, and also investigated how the brain pattern predict the social behavior performance under placebo manipulation.

Detailed Description

Participants were randomly assigned to spray+ group (sprayed with saline but told as "oxytocin") and control group (sprayed with saline but told as "saline"). After 10 min, participants were invited to the resting-state, text viewing task in fMRI scanner.

In resting state session, participants with their eyes open and were instructed to attend to a black fixation cross centrally presented on a grey projection screen for 8 min (240TR).

The Text viewing task employed a mixed block and even-related fMRI design. Participants were asked to judge whether they could understand the stimuli or not by a button press (1=understand; 2=not understand). Three kinds of stimuli were presented in separate block including "oxytocin-function", "oxytocin-knowledge", "robot" related stimuli, each category contained 20 sentences. In each block, the sentence (within one category) was presented pseudo-randomized from 5s to 9s (with mean duration of 7s), then followed by a jittered time interval (interval time = sentence duration - response time; if participants made response within 5s, the sentence would not disappear until its duration reached 5s). There were two sessions with six blocks per session, and there were 5 sentences (trials) per block. The order of blocks and sentences were designed to present in pseudo-random order and were applied to all participants.

Conditions

Spray+ Group; Control Group

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: DOUBLE

Study Groups

spray+ group

In spray+ condition, participants learned oxytocin materials on a self-paced basis and then intranasally administered with saline (but it was told as "oxytocin"). Participants were instructed to refrain from smoking or drinking (except water) for 2 h before the experiment. The spray was administered to each participant three times, and each administration consisted of one inhalation into each nostril. Participants took a rest (they were told it was a time period waiting for treatment to produce effects) for 10min and then performed the experimental tasks.

Group Type: EXPERIMENTAL

spray+ manipulation

Intervention Type: BEHAVIORAL

Participants in spray+ group received placebo manipulation and were told they sprayed was oxytocin (in fact, it was saline);

control group

In control condition, the materials and procedure were same with the spray+ condition except the nasal spray was told as "saline" instead. Oxytocin materials used in current experiments were adopted from previous study

Group Type: PLACEBO_COMPARATOR

control manipulation

Intervention Type: BEHAVIORAL

Participants in control group were told they sprayed saline (in fact, it was saline).

Interventions

spray+ manipulation

Participants in spray+ group received placebo manipulation and were told they sprayed was oxytocin (in fact, it was saline);

Intervention Type: BEHAVIORAL

control manipulation

Participants in control group were told they sprayed saline (in fact, it was saline).

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• All participants had normal or corrected-to-normal vision, and mental healthy.

Exclusion Criteria

• Participants who reported no history of neurological, endocrine or psychiatric disorders, who majored in psychology in college or recently participated in any other drug study were not recruited.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 35 Years
• Eligible Sex: MALE
• Accepts Healthy Volunteers: Yes

Sponsors

Beijing Normal University

OTHER

Sponsor Role: lead

Responsible Party

ma, yina

Principal Investigator

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Beijing Normal University

Beijing, Beijing Municipality, China

Countries

China

Other Identifiers

FSPE

Identifier Type: -

Identifier Source: org_study_id