Healthy
Conditions
Brief summary
A behavioral study that will examine how pain perception is affected by different types of conditioning and by context, with a few participants and multiple sessions (N-of-few design).
Interventions
BEHAVIORALSymbolic conditioning
Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) through symbolic conditioning (no actual heat stimuli, only pictures of thermometers)
BEHAVIORALConditioning
Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) from experience (with actual heat stimuli).
BEHAVIORALInstructions
Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) from verbal instructions.
BEHAVIORALCounterfactual
Thermal stimuli will be either the better outcome or the worse outcome out of two possible outcomes.
Sponsors
National Institute of Mental Health (NIMH)
Trustees of Dartmouth College
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
Within-participant design with behavioral manipulations.
Eligibility
Sex/Gender
ALL
Age
18 Years to 55 Years
Healthy volunteers
Yes
Inclusion criteria
* Healthy participants
Exclusion criteria
* Cannot tolerate heat pain applied to the forearm/leg, based on a calibration task at the beginning of the experiment
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Within Participant Subjective Ratings of Acute Thermal Pain, When it is the Worse vs. the Better Alternative | Measured repeatedly during pain tasks, in each of the last 4 sessions of the experiment, immediately after thermal stimuli. Averaged across sessions and compared across conditions. | In the counterfactual task, participants are presented with two alternatives (either two pain levels, or one pain level and either losing or gaining a certain amount of money). In these pairs of alternatives, the medium level pain is sometimes the better option (i.e., when the alternative is losing money or a more intense pain stimulus) and sometimes the worse option (i.e., when the other alternative is gaining money or a less intense pain stimulus). One of the two options is chosen by the computer (participants have no control on this choice). The investigators will compare the pain ratings (scale 0-180) within participant for the same level pain stimulus (medium intensity) when it is the worse vs. the better option. |
| Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Symbolic Learning) | Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions. | Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the symbolic learning procedure, cues are conditioned to different temperatures based on pictures of thermometers (instead of actual thermal stimuli as in the conditioning procedure). For the cues that were learned via symbolic learning, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant. |
| Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Conditioning) | Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions. | Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the conditioning procedure, cues are conditioned to different temperatures by delivering thermal stimuli with different temperatures after cues are presented (higher temperature following high cues and lower temperature following low cues). For the cues that were learned via conditioning, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant. |
| Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Instructions Only) | Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions. | Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the instructions only condition, cues are learned via verbal suggestion. For the cues that were learned via instructions only, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant. |
Other
| Measure | Time frame | Description |
|---|---|---|
| Within Participant Facial Expressions | Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions. | The investigators will obtain continuous facial video recordings of participants during the pain tasks with a video camera. The investigators will analyze these data according to Facial Action Units (facial expressions) that are known to be related to pain, and compare them across conditions. |
| Within Participant Thermal Imaging of the Face | Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions. | The investigators will obtain thermal recordings of participant's face with an infrared camera, and compare the heat signature of the face (the temperature in different parts of the face) across conditions. |
| Within Participant Changes in Skin Conductance Response Measured With a Biopac MP160 Device | Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions. | Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Skin conductance will be measured continuously. The investigators will compare the skin conductance response to pain stimuli within participant across conditions. |
| Within Participant Changes in Subjective Ratings of Pain Expectations | Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately before thermal stimuli. Averaged and compared across conditions. | Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Before some of the thermal stimuli, participants are asked to rate how painful they expect the next stimulus to be, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher expectations ratings. The investigators will compare the expectation ratings within participant across conditions. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Main Arm Symbolic conditioning: Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) through symbolic conditioning (no actual heat stimuli, only pictures of thermometers)
Conditioning: Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) from experience (with actual heat stimuli).
Instructions: Participants will learn associations between cues and thermal stimuli with varying temperatures (low vs. high) from verbal instructions.
Counterfactual: Thermal stimuli will be either the better outcome or the worse outcome out of two possible outcomes. | 8 |
| Total | 8 |
Withdrawals & dropouts
| Period | Reason | FG000 |
|---|---|---|
| Overall Study | Withdrawal by Subject | 2 |
Baseline characteristics
| Characteristic | Main Arm |
|---|---|
| Age, Continuous | 20.875 years STANDARD_DEVIATION 1.126 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 2 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 6 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 2 Participants |
| Race (NIH/OMB) Black or African American | 0 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 1 Participants |
| Race (NIH/OMB) White | 5 Participants |
| Region of Enrollment United States | 8 participants |
| Sex: Female, Male Female | 6 Participants |
| Sex: Female, Male Male | 2 Participants |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 0 / 8 |
| other Total, other adverse events | 0 / 8 |
| serious Total, serious adverse events | 0 / 8 |
Outcome results
Primary
Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Conditioning)
Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the conditioning procedure, cues are conditioned to different temperatures by delivering thermal stimuli with different temperatures after cues are presented (higher temperature following high cues and lower temperature following low cues). For the cues that were learned via conditioning, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant.
Time frame: Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| N-of-few Study of Pain | Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Conditioning) | 13.21 score on a scale | Standard Deviation 17.72 |
p-value: 0.036t-test, 1 sided
Primary
Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Instructions Only)
Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the instructions only condition, cues are learned via verbal suggestion. For the cues that were learned via instructions only, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant.
Time frame: Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| N-of-few Study of Pain | Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Instructions Only) | 13.76 score on a scale | Standard Deviation 13.51 |
p-value: 0.012t-test, 1 sided
Primary
Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Symbolic Learning)
Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Following each thermal stimulus, participants are asked to rate how painful it was, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher pain ratings. In the symbolic learning procedure, cues are conditioned to different temperatures based on pictures of thermometers (instead of actual thermal stimuli as in the conditioning procedure). For the cues that were learned via symbolic learning, the investigators will compare the average rating of pain for stimuli that are preceded by high cues minus the average rating of pain for stimuli that are preceded by low cues (each averaged across sessions), within participant.
Time frame: Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately after thermal stimuli. Averaged across sessions and compared across conditions.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| N-of-few Study of Pain | Within Participant Subjective Ratings of Acute Thermal Pain Following High Compared to Low Cues (Learned Via Symbolic Learning) | 7.32 score on a scale | Standard Deviation 10.41 |
p-value: 0.043t-test, 1 sided
Primary
Within Participant Subjective Ratings of Acute Thermal Pain, When it is the Worse vs. the Better Alternative
In the counterfactual task, participants are presented with two alternatives (either two pain levels, or one pain level and either losing or gaining a certain amount of money). In these pairs of alternatives, the medium level pain is sometimes the better option (i.e., when the alternative is losing money or a more intense pain stimulus) and sometimes the worse option (i.e., when the other alternative is gaining money or a less intense pain stimulus). One of the two options is chosen by the computer (participants have no control on this choice). The investigators will compare the pain ratings (scale 0-180) within participant for the same level pain stimulus (medium intensity) when it is the worse vs. the better option.
Time frame: Measured repeatedly during pain tasks, in each of the last 4 sessions of the experiment, immediately after thermal stimuli. Averaged across sessions and compared across conditions.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| N-of-few Study of Pain | Within Participant Subjective Ratings of Acute Thermal Pain, When it is the Worse vs. the Better Alternative | -2.06 score on a scale | Standard Deviation 5.57 |
p-value: 0.835t-test, 1 sided
Other Pre-specified
Within Participant Changes in Skin Conductance Response Measured With a Biopac MP160 Device
Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Skin conductance will be measured continuously. The investigators will compare the skin conductance response to pain stimuli within participant across conditions.
Time frame: Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions.
Other Pre-specified
Within Participant Changes in Subjective Ratings of Pain Expectations
Each session of the experiment includes pain tasks, in which multiple thermal stimuli are delivered. Before some of the thermal stimuli, participants are asked to rate how painful they expect the next stimulus to be, on a semi-circular computerized scale. Ratings are based on the angle (0-180), with higher angle representing higher expectations ratings. The investigators will compare the expectation ratings within participant across conditions.
Time frame: Measured repeatedly during pain tasks, in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability), immediately before thermal stimuli. Averaged and compared across conditions.
Other Pre-specified
Within Participant Facial Expressions
The investigators will obtain continuous facial video recordings of participants during the pain tasks with a video camera. The investigators will analyze these data according to Facial Action Units (facial expressions) that are known to be related to pain, and compare them across conditions.
Time frame: Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions.
Other Pre-specified
Within Participant Thermal Imaging of the Face
The investigators will obtain thermal recordings of participant's face with an infrared camera, and compare the heat signature of the face (the temperature in different parts of the face) across conditions.
Time frame: Measured continuously during pain stimuli in each of the 10 sessions of the experiment (up to 3 sessions per week, depending on the participants' availability). Averaged and compared across conditions.