Effects of Expectations on Negative Affect, Perceived Cognitive Effort, and Pain: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Expectations on Negative Affect, Perceived Cognitive Effort, and Pain (NCT05425563), a na na study. The primary outcome is Behavioral: Within Participant Subjective Outcome Ratings of Acute Thermal Pain Following High Compared to Low Cues.

2. Clinical Question

3. Trial Design

This completed study is registered as a single-group experiment, with allocation listed as not applicable and masking listed as none. The registry records an enrollment of 133. It does not describe a randomized, parallel-group treatment comparison. Instead, the primary outcome is constructed from ratings made by participants after exposure to high and low cues.

The experiment includes tasks concerning somatic pain, vicarious pain, and cognitive effort. For the somatic-pain task, participants receive a brief thermal stimulus on an arm and report perceived pain. For vicarious pain, they watch a short clip involving a patient with back or shoulder pain. For cognitive effort, they complete a mental-rotation task involving judgments about rotated three-dimensional objects. A functional neuroimaging task is also described, but imaging outcomes are not the primary endpoint discussed in the registry record.

Trials are described as proceeding through a fixation, a social-influence cue, an expectation rating, a task-specific stimulus, and an outcome rating. The record describes three sessions and says outcome ratings are averaged across sessions before the high-versus-low cue contrast is formed. Further details about session scheduling, cue order, counterbalancing, and the exact number of trials are not reported in the registry record.

The study is marked completed. Its recorded start date is 2020-11-23, and its primary completion date is 2022-07-08. The registry lists behavioral cue interventions for pain expectancy, vicarious-pain expectancy, and cognitive-effort expectancy. These labels describe the experimental cue tasks, not separate randomized treatment arms.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Behavioral: Within Participant Subjective Outcome Ratings of Acute Thermal Pain Following High Compared to Low Cues, measured over Within trials, outcome ratings are collected post-stimulus (4s window); Trials are collected across 3 sessions. Ratings are then averaged, and contrasted to a single outcome measure: perceived pain as a function of high low cue exposure..

The primary endpoint is a within-participant contrast in subjective outcome ratings of acute thermal pain after high versus low cues. Participants rate perceived pain on a semicircular scale from 0 to 180 degrees, with higher angles indicating greater perceived pain. Ratings are grouped by cue condition and averaged across sessions; the endpoint is the difference between the average after high cues and the average after low cues.

This contrast is intended to represent how reported pain differs according to the expectancy cue that preceded the thermal stimulus. Using each participant’s ratings under both cue conditions makes the question about a within-person difference rather than a comparison of two separate groups. It can therefore describe the cue-associated contrast in this experiment, while still requiring appropriate analysis of the paired observations.

The registry gives the endpoint’s measurement scale and calculation but does not report the observed contrast, its standard error, a confidence interval, or a test result. Consequently, the direction, magnitude, and precision of the primary endpoint cannot be established from the registry record. The endpoint is a rating of perceived pain, not a direct measurement of tissue injury or an objective measure of pain intensity.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous primary measure summarized as a mean and reports standard error as the dispersion measure. The endpoint is formed by averaging subjective pain ratings separately after high and low cues, then taking a contrast between those averages. The record does not report the statistical test or model used to analyze that contrast.

What does a within-participant contrast represent?

In general, a within-participant comparison uses observations from the same person under more than one condition. Each participant can contribute a rating after a high cue and a rating after a low cue. The contrast asks whether ratings tend to differ between those conditions across participants. This approach accounts for the fact that people may use a rating scale differently or have different baseline response levels, because the comparison is made within the same person.

Paired observations are not independent. A statistical analysis should reflect the relationship between a participant’s ratings across conditions; treating all high-cue and low-cue observations as unrelated would ignore that pairing. The registry record does not specify which paired-data method, model, or variance assumptions were used. It also does not report whether session-level observations were modeled directly or reduced to averages before analysis beyond the described endpoint calculation.

What does the standard error describe?

In general, a standard error describes the estimated sampling variability of a statistic, such as a mean or contrast. It is not the same as the spread of individual participants’ ratings. A small standard error indicates that an estimate would tend to vary less across repeated samples under the model’s assumptions; it does not, by itself, show that the estimate is large, important, or unbiased. No primary standard error value is reported in the registry record, so the precision of the pain contrast cannot be quantified from it.

Why are repeated observations relevant?

The record describes trials collected across three sessions and ratings averaged across sessions. Repeated observations from the same participant can be correlated. In general, a model for repeated data may need to represent that dependence, or a participant-level summary may be used if that matches the analysis plan. Averaging can yield a concise endpoint, but it can also obscure variation across sessions or trials. The registry does not report whether session-specific patterns, trial-level variation, or within-person correlation were examined.

What does the scale allow?

The pain rating uses a semicircular scale from 0 to 180 degrees, and higher angles indicate greater reported pain. The endpoint treats the resulting ratings as a continuous measure and summarizes them with a mean. In general, a mean is useful for describing average responses, but it can be influenced by extreme observations and does not describe the full distribution. A standard error around a mean addresses uncertainty in that mean, not the range of individual experiences. Distributional summaries and diagnostic checks are not reported in the registry record.

What can be said about planning calculations?

The registry describes planning illustrations based on the observed effect, a stated fraction of that effect, two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. These are planning assumptions, not evidence that the study actually used a two-arm design; the registered study is single group, and the primary comparison is within participant. The illustrations are not observed power. Sample-size calculations based on an observed effect can be sensitive to the uncertainty in that effect, so they should not be read as independent confirmation of the result. The exact planning values and the trial’s own sample-size justification are not reported in the registry record.

General statistical interpretation also depends on the prespecified analysis, assumptions, and handling of incomplete data. The registry does not report the primary model, a hypothesis-testing procedure, the treatment of outliers, or diagnostic checks. Without these details and the numerical result, readers cannot verify the analysis or judge whether its assumptions are reasonable.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Pain Task; Cue-modulated Stimulus Intensity")
n   <- c(116)
m   <- c(8.2)
sp  <- c(0.89)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Pain Task; Cue-modulated Stimulus Intensity  116  8.200  9.586  6.437  9.963

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 22 outcome measures and six analyses. The listed outcomes include expectation ratings following high or low cues across acute thermal pain, vicarious pain, and cognitive effort, as well as the primary subjective thermal-pain outcome. The record does not report a multiplicity-control procedure, a hierarchy of confirmatory and exploratory outcomes, or which analyses were considered primary beyond the endpoint designation.

When many outcomes or analyses are examined, the chance of obtaining at least one apparently notable result can increase. In general, multiplicity procedures can control that risk, while a prespecified hierarchy can distinguish the main confirmatory question from secondary questions. The registry does not state whether such procedures were used. No adjustment should therefore be assumed, and no claim about statistical significance across outcomes can be made from the listed information.

Missing-data methods and the number of participants contributing to each outcome are not reported in the registry record. The enrollment of 133 does not establish how many participants completed each task or contributed to the primary contrast. The record does not describe exclusions, incomplete ratings, participant withdrawal, or the assumptions used for any missing observations.

Analysis populations are also not described. The registry does not specify whether the primary result was based on all enrolled participants, participants who completed particular tasks, or another defined group. It does not report whether deviations from the task procedures were handled in a particular way. These omissions limit assessment of attrition, selection, and the relationship between enrollment and the analyzed sample.

12. What the Result Does, and Does Not, Mean

The primary endpoint is designed to describe whether average self-reported thermal-pain ratings differ after high versus low expectancy cues in this experimental setting. It concerns a contrast within participants, not a comparison of separate treatment groups. The registry record does not report the numerical contrast or its uncertainty, so it does not establish the observed direction or magnitude of that difference.

Even if a numerical contrast were available, its interpretation would remain specific to the tested tasks, cue presentation, and rating procedure. The outcome is subjective pain perception reported on a scale, and the study includes a constructed social-influence cue. A difference in ratings would describe an association between cue condition and reported outcome under the experiment’s procedures; it would not by itself establish how the result generalizes to other settings or populations.

The record also describes vicarious-pain and cognitive-effort tasks, but the primary endpoint is acute thermal pain. Findings from one outcome should not automatically be extended to the other tasks. The registry does not report results for those secondary outcomes in the information available for this analysis.

This study does not provide a randomized comparison between treatment arms, and its primary endpoint is not a clinical treatment outcome. It cannot, on the basis of the registry entries alone, answer whether an intervention improves health or should be used in practice. It is an experiment about expectancy cues and participants’ ratings across affective and cognitive tasks.

The registry’s completed status indicates that the study is recorded as completed, but completion does not mean that all results or analysis details are present. The primary effect estimate, uncertainty, missing-data handling, and detailed statistical plan are not reported in the registry record. Those absences prevent a quantitative assessment of the strength and precision of the primary finding.

13. Why This Trial Matters Statistically

This experiment raises a statistical question about how a within-participant cue contrast should be defined and interpreted. The same participants contribute ratings following high and low cues, so the relevant information lies in the paired differences rather than in two unrelated group averages. Recognizing the dependence between conditions is essential to estimating uncertainty appropriately.

The outcome is also built from several levels of repeated measurement: ratings follow stimuli within trials, and trials are collected across sessions. The registry describes averaging across sessions but does not report the complete analysis model. This makes clear why endpoint construction and analysis details matter: summaries can simplify repeated data, but can also hide variation that may affect interpretation.

The study’s several tasks and listed outcomes create a further statistical issue. A primary contrast can provide a focused question, while additional outcomes may be useful for exploring related responses. Without a reported multiplicity strategy and outcome hierarchy, readers cannot determine how the full set of analyses was interpreted.

Finally, the record distinguishes the experimental question from a conventional treatment trial. It describes a single-group study with cue conditions rather than randomized arms, and the primary outcome is subjective experience. Careful wording prevents the cue contrast from being mistaken for a treatment effect or for an objective measure of pain. The absence of the primary estimate and its uncertainty also underscores that design descriptions alone cannot establish what the observed data show.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several design and reporting limitations restrict interpretation. The registry records a single-group model, allocation as not applicable, and no masking. The primary high-versus-low comparison is within participant, but the record does not report cue-order procedures, counterbalancing, or other details that would clarify whether order or carryover could influence the contrast.

The primary outcome is self-reported pain on a semicircular 0-180 degree scale. It is appropriate to the stated question about perceived pain, but it is not an objective measure of pain and may reflect the reporting context as well as the stimulus experience. The cue ratings were fabricated while participants were told they were real, according to the experiment description. The registry does not report how participants’ awareness of this feature was assessed.

The analysis details needed to evaluate the primary estimate are incomplete. The numerical contrast and its uncertainty are not reported, and the statistical test or model is not specified. The registry also does not report missing-data handling, analysis populations, distributional checks, or the approach to multiple outcomes and analyses.

Enrollment is recorded as 133, but the number contributing data to each task or to the primary endpoint is not reported in the registry record. Details about participant characteristics and eligibility are also not reported. The study includes several experimental tasks, but the primary endpoint concerns thermal pain; the extent to which findings would apply to other tasks or settings cannot be assessed from this record alone.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effects of Expectations on Negative Affect, Perceived Cognitive Effort, and Pain — NCT05425563.
• Registry record last updated 2023-11-30; status last verified 2023-11.
• Results first posted 2023-11-30.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT05425563 is a completed, single-group experiment titled “Effects of Expectations on Negative Affect, Perceived Cognitive Effort, and Pain.” The sponsor is Trustees of Dartmouth College. The registry records enrollment of 133, a start date of 2020-11-23, and a primary completion date of 2022-07-08.

The experiment uses expectancy cues in tasks involving somatic pain, vicarious pain, and cognitive effort. Its primary outcome is the within-participant contrast in average subjective acute thermal-pain ratings following high versus low cues, on a 0-180 degree scale. The registry record does not report the primary contrast estimate, its standard error, confidence interval, or p-value. The statistical analysis plan, missing-data approach, and analysis populations are not reported in the registry record.