LSD ReactionLUCYNCT05976698
LSD-Perceptual-Choice-Study
A study testing LSD 10 μg and LSD 20 μg in people with LSD Reaction, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.
Trial summary
The aim of the study is to characterize the effects of low doses of LSD (d-lysergic acid diethylamide) on behavioral and neural indicators of feedback and feedforward signaling in perceptual decision-making. Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- LSD Reaction
- What is being tested?
- LSD 10 μg and LSD 20 μg
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 30 participants
- Where
- 1 siteSwitzerland
- Study dates
- 26 Feb 2024to 25 Feb 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Willingness to adhere to the study protocol and sign the consent form
- ≥ 18 and ≤ 65 years of age at Screening
- Body mass index 18-29
- Fluent understanding of German
- Normal or corrected-to-normal vision
- Willingness to not operate a traffic vehicle or heavy machinery 24 hours after substance administration
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- Willingness to refrain from taking illicit psychoactive substances, including cannabis, for the duration of the study
- Willingness to not consume more than one alcoholic standard drink the night before the study sessions and not consume alcohol for 24 h after each study session
- Willingness to abstain from xanthine-based liquids from the evenings prior to the study sessions and during the sessions
- Willingness to use effective birth-control throughout the study duration
- Adequate task performance in the decision-making tasks during a practice session in the screening visit
Who cannot join
- Recent (<30 days) or current participation in another clinical trial
- Women that are pregnant, nursing, or planning to become pregnant during the study period
- Current use of contraindicated/psychoactive medications or illicit drugs
- Lifetime use of classical psychedelics more than 20 times, or any time within the previous two months
- Consumption of >5 cigarettes per day or >20 alcoholic standard drinks per week
- Severe chronic or acute medical condition
Show all 9Show fewer
- Hypertension (>140/90 mmHg) or hypotension (<85mmHg systolic)
- Current or lifetime major mental health disorder
- Personal or family (first-degree) history of a primary psychotic disorder
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Effects of LSD on Perceptual Decision-making in Healthy Subjects
The aim of the study is to characterize the effects of low doses of LSD (d-lysergic acid diethylamide) on behavioral and neural indicators of feedback and feedforward signaling in perceptual decision-making.
Read the detailed description
The study team will subject healthy participants to multiple perceptual decision-making tasks after the administration of low doses of LSD (d-lysergic acid diethylamide) as a pharmacological challenge. The investigators want to illuminate the behavioral and neural effects of psychedelics on prior beliefs and evidence processing. Each subject will participate in 3 x 5 h study sessions separated by at least 7 days. Subjects will be under continuous supervision until approximately 4.5h after substance administration. The participants are asked to perform the following cognitive tasks alongside EEG measurement after administration of either LSD or placebo: Changepoint task, history bias task, surround suppression task, auditory steady-state response paradigm, motor localizer task.
- Conditions
- LSD Reaction
- Being tested
- LSD 10 μg, LSD 20 μg, Placebo
- Keywords
- neural and behavioral indicators, serotonergic system, perceptual decision-making
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
LSD 10 μgDrug
0.5 h after the start of each study session the participants will be administered 10 μg LSD per os in the form of vials containing 1ml 20% EtOH (ethanol).
LSD 20 μgDrug
0.5 h after the start of each study session the participants will be administered 20 μg LSD per os in the form of vials containing 1ml 20% EtOH.
PlaceboDrug
0.5 h after the start of each study session the participants will be administered placebo per os in the form of vials containing 1ml 20% EtOH.
| Study group | Role | What they receive |
|---|---|---|
| Intervention order: 10 μg LSD - 20 μg LSD - Placebo | Experimental | Each subject will participate in 3 x 5 h study sessions separated by at least 7 days.
Order of drug administration will be 10 μg LSD - 20 μg LSD - Placebo. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+placebo; 2. visit: active+active, 3. visit: placebo+placebo. Receives: Drug: LSD 10 μg; Drug: LSD 20 μg; Drug: Placebo |
| Intervention order: 10 μg LSD - Placebo - 20 μg LSD | Experimental | Each subject will participate in 3 x 5 h study sessions separated by at least 7 days.
Order of drug administration will be 10 μg LSD - Placebo - 20 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+placebo; 2. visit: placebo+placebo, 3. visit: active+active. Receives: Drug: LSD 10 μg; Drug: LSD 20 μg; Drug: Placebo |
| Intervention order: 20 μg LSD - 10 μg LSD - Placebo | Experimental | Each subject will participate in 3 x 5 h study sessions separated by at least 7 days.
Order of drug administration will be 20 μg LSD - 10 μg LSD - Placebo. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+active; 2. visit: active+placebo, 3. visit: placebo+placebo. Receives: Drug: LSD 10 μg; Drug: LSD 20 μg; Drug: Placebo |
| Intervention order: 20 μg LSD - placebo - 10 μg LSD | Experimental | Each subject will participate in 3 x 5 h study sessions separated by at least 7 days.
Order of drug administration will be 20 μg LSD -placebo - 10 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+active; 2. visit: placebo+placebo, 3. visit: active+placebo. Receives: Drug: LSD 10 μg; Drug: LSD 20 μg; Drug: Placebo |
| Intervention order: placebo - 10 μg LSD - 20 μg LSD | Experimental | Each subject will participate in 3 x 5 h study sessions separated by at least 7 days.
Order of drug administration will be placebo - 10 μg LSD - 20 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: placebo+placebo; 2. visit: active+placebo, 3. visit: active+active. Receives: Drug: LSD 10 μg; Drug: LSD 20 μg; Drug: Placebo |
| Intervention order: placebo - 20 μg LSD - 10 μg LSD | Experimental | Each subject will participate in 3 x 5 h study sessions separated by at least 7 days.
Order of drug administration will be placebo - 20 μg LSD - 10 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: placebo+placebo; 2. visit: active+active, 3. visit: active+placebo. Receives: Drug: LSD 10 μg; Drug: LSD 20 μg; Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in changepoint task
Using the changepoint task, it is examined how explicit expectations about upcoming stimuli are derived from the perceptual history and how they influence the perceptual decision in a volatile environment.
The study team utilizes an established computerized task and analysis pipeline including a behavioral modeling strategy based on Bayesian inference. The task requires participants to view a train of stimuli consisting of checkerboards presented on a half-circle gradient either more on the right or more on the left side of a fixation cross. Each checkerboard represents information about whether stimuli are currently more likely to appear on the right or left side of the screen. The participants have to indicate by button press, whether they believe the right or the left side is active. Task difficulty is fixed.
Measured: three times (once on each of the three test days; interval between test days at least 7 days)
Change in history bias task
With the history bias task, the study team investigates how implicit expectations about upcoming stimuli are derived from perceptual history and how they bias perceptual discrimination.
In each trial, two circular gratings will be presented concurrently on the left and right sides of a fixation cross. After complete stimulus presentation, the participants indicate by button press which of the two gratings they believe had the stronger contrast in the trial (left vs. right). Task difficulty will be adjusted individually using an online quest staircase procedure, such that participants will always perform at their 75% accuracy level.
Measured: three times (once on each of the three test days; interval between test days at least 7 days)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Aug 2023
- Study start26 Feb 2024
- Primary completion25 Feb 2025
- Study completion25 Feb 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for LSD ReactionStudies of the same condition, open and under way.
- More trials run by University Hospital, Basel, SwitzerlandThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Randomized, double-blinded, cross-over study
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 30 participants (actual)
Sponsor and investigators
- Lead sponsor
- University Hospital, Basel, Switzerland
- Sponsor type
- University, hospital or other
- Collaborators
- University of Basel, University Psychiatric Clinics Basel
- Responsible party
- Sponsor
- Investigators
- Philipp Sterzer, Prof. Dr., Principal investigator, University Psychiatric Clinics Basel
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05976698
- Sponsor's protocol ID
- 2023-00763, pk23Sterzer
- Other IDs
- 2023
- Acronym
- LUCY
- Status last verified
- May 2026
- First submitted
- 24 Jul 2023
- Last updated
- 29 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 29 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of LSD on Perceptual Decision-making in Healthy Subjects
- ClinicalTrials.gov ID
- NCT05976698
- Acronym / sponsor ID
- LUCY / 2023-00763, pk23Sterzer
- Conditions
- LSD Reaction
- Keywords
- neural and behavioral indicators, serotonergic system, perceptual decision-making
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 30 participants (actual)
- Lead sponsor
- University Hospital, Basel, SwitzerlandUniversity, hospital or other
- Collaborators
- University of Basel, University Psychiatric Clinics Basel
- Study start
- 26 Feb 2024 (actual)
- Primary completion
- 25 Feb 2025 (actual)
- Study completion
- 25 Feb 2025 (actual)
- First posted
- 4 Aug 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The aim of the study is to characterize the effects of low doses of LSD (d-lysergic acid diethylamide) on behavioral and neural indicators of feedback and feedforward signaling in perceptual decision-making.
Detailed description
The study team will subject healthy participants to multiple perceptual decision-making tasks after the administration of low doses of LSD (d-lysergic acid diethylamide) as a pharmacological challenge. The investigators want to illuminate the behavioral and neural effects of psychedelics on prior beliefs and evidence processing. Each subject will participate in 3 x 5 h study sessions separated by at least 7 days. Subjects will be under continuous supervision until approximately 4.5h after substance administration. The participants are asked to perform the following cognitive tasks alongside EEG measurement after administration of either LSD or placebo: Changepoint task, history bias task, surround suppression task, auditory steady-state response paradigm, motor localizer task.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Double blind (participant, investigator)
- Number of arms
- 6
- Model description
- Randomized, double-blinded, cross-over study
| Arm | Type | Receives |
|---|---|---|
| Intervention order: 10 μg LSD - 20 μg LSD - Placebo | Experimental | Drug: LSD 10 μg, Drug: LSD 20 μg, Drug: PlaceboEach subject will participate in 3 x 5 h study sessions separated by at least 7 days. Order of drug administration will be 10 μg LSD - 20 μg LSD - Placebo. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+placebo; 2. visit: active+active, 3. visit: placebo+placebo. |
| Intervention order: 10 μg LSD - Placebo - 20 μg LSD | Experimental | Drug: LSD 10 μg, Drug: LSD 20 μg, Drug: PlaceboEach subject will participate in 3 x 5 h study sessions separated by at least 7 days. Order of drug administration will be 10 μg LSD - Placebo - 20 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+placebo; 2. visit: placebo+placebo, 3. visit: active+active. |
| Intervention order: 20 μg LSD - 10 μg LSD - Placebo | Experimental | Drug: LSD 10 μg, Drug: LSD 20 μg, Drug: PlaceboEach subject will participate in 3 x 5 h study sessions separated by at least 7 days. Order of drug administration will be 20 μg LSD - 10 μg LSD - Placebo. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+active; 2. visit: active+placebo, 3. visit: placebo+placebo. |
| Intervention order: 20 μg LSD - placebo - 10 μg LSD | Experimental | Drug: LSD 10 μg, Drug: LSD 20 μg, Drug: PlaceboEach subject will participate in 3 x 5 h study sessions separated by at least 7 days. Order of drug administration will be 20 μg LSD -placebo - 10 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: active+active; 2. visit: placebo+placebo, 3. visit: active+placebo. |
| Intervention order: placebo - 10 μg LSD - 20 μg LSD | Experimental | Drug: LSD 10 μg, Drug: LSD 20 μg, Drug: PlaceboEach subject will participate in 3 x 5 h study sessions separated by at least 7 days. Order of drug administration will be placebo - 10 μg LSD - 20 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: placebo+placebo; 2. visit: active+placebo, 3. visit: active+active. |
| Intervention order: placebo - 20 μg LSD - 10 μg LSD | Experimental | Drug: LSD 10 μg, Drug: LSD 20 μg, Drug: PlaceboEach subject will participate in 3 x 5 h study sessions separated by at least 7 days. Order of drug administration will be placebo - 20 μg LSD - 10 μg LSD. Vials will contain either 10μg (Active) or 0 μg LSD (Placebo). Thus, participants will be administered two vials on each study visit. 1. visit: placebo+placebo; 2. visit: active+active, 3. visit: active+placebo. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- Willingness to adhere to the study protocol and sign the consent form
- ≥ 18 and ≤ 65 years of age at Screening
- Body mass index 18-29
- Fluent understanding of German
- Normal or corrected-to-normal vision
Key exclusion criteria (9 listed)
- Recent (<30 days) or current participation in another clinical trial
- Women that are pregnant, nursing, or planning to become pregnant during the study period
- Current use of contraindicated/psychoactive medications or illicit drugs
- Lifetime use of classical psychedelics more than 20 times, or any time within the previous two months
- Consumption of >5 cigarettes per day or >20 alcoholic standard drinks per week
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| LSD 10 μg0.5 h after the start of each study session the participants will be administered 10 μg LSD per os in the form of vials containing 1ml 20% EtOH (ethanol). | Drug | Intervention order: 10 μg LSD - 20 μg LSD - Placebo, Intervention order: 10 μg LSD - Placebo - 20 μg LSD, Intervention order: 20 μg LSD - 10 μg LSD - Placebo, Intervention order: 20 μg LSD - placebo - 10 μg LSD, Intervention order: placebo - 10 μg LSD - 20 μg LSD, Intervention order: placebo - 20 μg LSD - 10 μg LSD |
| LSD 20 μg0.5 h after the start of each study session the participants will be administered 20 μg LSD per os in the form of vials containing 1ml 20% EtOH. | Drug | Intervention order: 10 μg LSD - 20 μg LSD - Placebo, Intervention order: 10 μg LSD - Placebo - 20 μg LSD, Intervention order: 20 μg LSD - 10 μg LSD - Placebo, Intervention order: 20 μg LSD - placebo - 10 μg LSD, Intervention order: placebo - 10 μg LSD - 20 μg LSD, Intervention order: placebo - 20 μg LSD - 10 μg LSD |
| Placebo0.5 h after the start of each study session the participants will be administered placebo per os in the form of vials containing 1ml 20% EtOH. | Drug | Intervention order: 10 μg LSD - 20 μg LSD - Placebo, Intervention order: 10 μg LSD - Placebo - 20 μg LSD, Intervention order: 20 μg LSD - 10 μg LSD - Placebo, Intervention order: 20 μg LSD - placebo - 10 μg LSD, Intervention order: placebo - 10 μg LSD - 20 μg LSD, Intervention order: placebo - 20 μg LSD - 10 μg LSD |
Primary outcome
Change in changepoint task
Time frame: three times (once on each of the three test days; interval between test days at least 7 days)
Using the changepoint task, it is examined how explicit expectations about upcoming stimuli are derived from the perceptual history and how they influence the perceptual decision in a volatile environment. The study team utilizes an established computerized task and analysis pipeline including a behavioral modeling strategy based on Bayesian inference. The task requires participants to view a train of stimuli consisting of checkerboards presented on a half-circle gradient either more on the right or more on the left side of a fixation cross. Each checkerboard represents information about whether stimuli are currently more likely to appear on the right or left side of the screen. The participants have to indicate by button press, whether they believe the right or the left side is active. Task difficulty is fixed.
Change in history bias task
Time frame: three times (once on each of the three test days; interval between test days at least 7 days)
With the history bias task, the study team investigates how implicit expectations about upcoming stimuli are derived from perceptual history and how they bias perceptual discrimination. In each trial, two circular gratings will be presented concurrently on the left and right sides of a fixation cross. After complete stimulus presentation, the participants indicate by button press which of the two gratings they believe had the stronger contrast in the trial (left vs. right). Task difficulty will be adjusted individually using an online quest staircase procedure, such that participants will always perform at their 75% accuracy level.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 29 May 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Philipp Sterzer, Prof. Dr. principal investigator
University Psychiatric Clinics Basel
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing LSD 10 μg and LSD 20 μg in people with LSD Reaction, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 11 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 29 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in changepoint task (time frame: three times (once on each of the three test days; interval between test days at least 7 days)). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 29 May 2026.