Visual Attention to Text and Pictorial Food Labels: An Eye Tracking Experiment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Visual Attention to Text and Pictorial Food Labels: An Eye Tracking Experiment (NCT05958888), a na na study. The primary outcome is Amount of Time Spent Looking at the Front-of-package Sodium Label (i.e., Dwell Time).

2. Clinical Question

The study is an attention experiment, not a report of clinical outcomes. Its central measurement is visual attention to food-label information during a task involving an image of a soup can. The listed secondary measures include fixation count, time to first fixation, dwell time on a “Natural” claim, self-reported attention, perceived message effectiveness and understandability. The registry record describes these outcomes but does not report their values or analyses. Consequently, the record establishes what the investigators intended to examine, but does not establish which label format attracted more attention or how precisely any differences were estimated.

3. Trial Design

This completed study is titled “Visual Attention to Text and Pictorial Food Labels: An Eye Tracking Experiment.” It is registered as NCT05958888 and lists University of North Carolina, Chapel Hill as sponsor. The recorded start date is 2023-08-02, and the primary completion date is 2023-09-29. Enrollment is 63. Phase and allocation are recorded as NA, masking as NONE, and the model as SINGLE GROUP.

The arm description says that four labels—three sodium labels and one control barcode label—are shown on an image of a soup can. The listed behavioral interventions are the text-only sodium label, icon sodium label, pictorial sodium label and barcode label. The record cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. It does not report a randomized allocation procedure, a masking procedure, or enough design detail to determine the order or exact exposure pattern for each participant. Those details are not reported in the registry record.

The primary outcome is amount of time spent looking at the front-of-package sodium label, measured in seconds using eye-tracking technology. The timeframe is described as a roughly five-minute eye-tracking task within a one-time study visit lasting roughly 30 minutes. The registry record lists six secondary outcomes related to visual attention and perceptions of the label. It also describes an aim to explore moderation by English language proficiency. The record does not report the analytic approach for that moderation question or the numerical findings for the primary or secondary outcomes.

The design information supports describing the project as a single-group experiment evaluating attention to label formats. It does not support treating the listed labels as randomized parallel arms or interpreting the barcode label as a fully comparable control condition.

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.

First Label Viewing (Self-paced)

Washout (Self-paced)

Second Label Viewing (Self-paced)

Washout (Self Paced)

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 Amount of Time Spent Looking at the Front-of-package Sodium Label (i.e., Dwell Time), measured over During ~5-minute eye tracking task, as part of a one-time study visit lasting ~30 minutes.

The primary endpoint is the amount of time spent looking at the front-of-package sodium label, measured in seconds during the eye-tracking task. The registry record specifies the mean as the summary parameter and standard deviation as the dispersion measure. It states that eye-tracking technology will be used and places the measure within a roughly five-minute task during a one-time visit lasting roughly 30 minutes.

Dwell time is used as a measure of visual attention: it records how much time a participant's gaze is directed to a defined label area. As a general statistical interpretation, this measure captures duration of attention, not necessarily comprehension, preference, or the ability to use the information. The record separately lists outcomes for fixation count, time to first fixation, self-reported attention, perceived message effectiveness and understandability, indicating that these are distinct aspects of attention or response rather than interchangeable measures.

The registry record does not report the observed mean dwell time, standard deviation, sample size contributing to the primary endpoint, or a comparison estimate. Thus the endpoint definition is available, but its observed magnitude and precision cannot be assessed from the registry record. A mean and standard deviation would describe the average duration and its variability; without those results, no label-specific conclusion about dwell time can be drawn.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods are only partly described in the registry record. The primary outcome is continuous, with the mean specified as the summary parameter and standard deviation as the measure of dispersion. The record states that dwell time is assessed using eye tracking. It does not report a statistical analysis plan, the model used for the primary outcome, adjustments for covariates, or the method used to handle repeated observations or other features of the task.

What does a mean and standard deviation describe?

General statistical explanation: the mean summarizes the average observed value in a group. The standard deviation describes how spread out individual values are around that mean. Reporting both can help readers distinguish an average level from the amount of participant-to-participant variability. Neither statistic, on its own, quantifies the uncertainty in a comparison between groups. The registry record identifies these summary measures but does not report their observed values for dwell time.

What would a comparison estimate show?

General statistical explanation: a comparison estimate describes the magnitude and direction of a contrast between conditions, while a confidence interval describes the range of estimates reasonably compatible with the data under the statistical model. A p-value addresses compatibility with a specified null hypothesis under that model; it does not measure the size or practical importance of an effect. The registry record does not report a primary comparison estimate, confidence interval or p-value. No conclusion about the direction, magnitude or precision of a label contrast can therefore be made from the record.

Why does the design description matter?

General statistical explanation: random allocation can help make comparison groups similar, on average, with respect to both measured and unmeasured participant characteristics. Without a randomized comparison, differences between label conditions may be difficult to separate from differences in who was exposed to each condition or how the task was conducted. Here, the record gives allocation as NA and describes a single-group model. It explicitly cautions that the arms are not a like-for-like control comparison. The record does not report enough additional detail to identify the exact source or likely direction of possible bias.

The label list includes text-only, icon, pictorial and barcode formats, and the arm description says that four labels are shown on an image of a soup can. The registry record does not explain the exposure sequence, whether all participants saw each label in the same way, or how label-level observations were assigned to analyses. It is therefore not possible to determine from the record whether a particular statistical model should account for within-participant dependence. General statistical explanation: when the same participant contributes measurements under multiple conditions, those observations are often correlated. Analyses that ignore such dependence may misstate uncertainty.

How should the planning assumptions be read?

The sample-size assumptions describe a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not a description of the study's own design. Any resulting sample sizes are illustrations rather than observed power. The registry record does not report the observed effect used for such calculations or the specific fractions represented. The study enrollment of 63 is a recorded study characteristic, not by itself evidence that the study had adequate power for any particular contrast.

General statistical explanation: over-dispersion occurs when observed variability exceeds what a chosen statistical model assumes. If that happens, standard errors and confidence intervals from the model may be too narrow unless the analysis accounts for the extra variability. The registry record does not report whether over-dispersion was assessed or relevant for the primary endpoint. This general issue should not be taken to mean that over-dispersion occurred in this experiment.

The record lists seven outcome measures and 42 analyses. It does not explain how the analyses were allocated across outcomes, label comparisons or subgroups, and it does not report whether any multiplicity adjustment was used. General statistical explanation: conducting multiple tests can increase the chance of observing at least one apparently unusual result by chance. Prespecified primary outcomes, transparent reporting of all planned comparisons and appropriate methods can help readers understand that risk. The registry record does not provide enough information to evaluate these aspects.

Finally, the record does not report missing-data procedures, an analysis population, outcome-specific denominators, exclusions, or a sensitivity analysis. These details matter because the people contributing usable eye-tracking data may differ from the full enrolled group. Without such information and without the outcome estimates, statistical precision and robustness cannot be assessed.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists seven outcome measures and 42 analyses. The primary outcome is dwell time on the front-of-package sodium label. The listed secondary outcomes cover fixation count, time to first fixation, dwell time on a “Natural” claim, self-reported attention, perceived message effectiveness and understandability. The record does not explain how the 42 analyses relate to these outcomes, label formats, or possible subgroups. It also does not report a multiplicity strategy or state whether analyses were prespecified.

General statistical explanation: when researchers conduct many tests, the chance that at least one result appears noteworthy by chance can increase. Adjustment methods, a clearly identified primary analysis and complete reporting can help readers interpret a collection of tests. Without the analysis plan and results, it is not possible to determine how multiplicity affects interpretation of this study.

Missing-data methods and analysis populations are not reported in the registry record. It does not state how missing or unusable eye-tracking measurements were handled, how many participants contributed to each outcome, what exclusions were applied, or whether sensitivity analyses were conducted. The enrollment of 63 should not be assumed to be the denominator for every outcome analysis.

General statistical explanation: missing observations can reduce precision, and bias can arise if the likelihood of having an observed measurement is related to participant characteristics or outcomes. The direction and magnitude of any such impact depend on the reasons for missingness and the analysis approach. The record provides no information to assess whether missingness occurred or how it might affect estimates.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry record lists four label groups: Text Only Sodium Label, Icon Sodium Label, Pictorial Sodium Label and Barcode Label. For each group it records 63 participants at risk for serious adverse events and 0 serious adverse events. It also records 63 at risk for other adverse events and 0 other adverse events in each group. Deaths are recorded as 0 in each group, and no serious adverse-event terms are listed.

These figures are registry entries, not a comparative safety analysis. The same enrollment figure appears for each label group, but the record does not explain the relationship between these group entries or provide outcome-specific analysis populations. The figures should not be added across groups to infer a distinct total number of participants, since the design is recorded as SINGLE GROUP and the record does not establish that the groups represent disjoint sets of people.

Zero recorded events means that the registry lists no events in these categories for the stated at-risk counts. It does not establish that every possible event was measured or reported, nor does it provide a comparative estimate with uncertainty. Further details about safety monitoring and event ascertainment are not reported in the registry record.

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

The registry record establishes that the study was designed to examine visual attention to front-of-package food labels using eye tracking, with dwell time on a sodium label designated as the primary endpoint. It also identifies several related attention and perception measures and an exploratory question about English language proficiency. The record does not report the numerical results for these outcomes.

Accordingly, the posted record does not show whether participants spent more time looking at one label format than another, whether label formats differed in fixation count or time to first fixation, or whether perceived message effectiveness or understandability varied. It also does not provide estimates or uncertainty measures for the proposed English proficiency moderation question. No effect direction, magnitude, or statistical precision can be inferred from the study aims alone.

The design cautions are important to the meaning of any contrast. Allocation is NA, the model is single group, and the record says that the arms are not a like-for-like control comparison. The barcode label is named as a control, but the registry record does not describe a randomized contrast that would justify interpreting it as an equivalent control group. Further details about exposure assignment and analysis are not reported in the registry record.

The record also does not establish that dwell time is equivalent to understanding or use of label information. As a general point, gaze duration is a measure of visual behavior; interpretation as comprehension or decision-making requires evidence from measures designed for those constructs. This study separately lists understandability and perceived message effectiveness outcomes, but their results are not reported.

The reported zero event counts describe the listed adverse-event entries only. They do not answer the attention questions, and they do not resolve the missing outcome information. The most defensible reading is therefore that the registry record documents the research questions, planned measures and limitations of the comparison, but does not provide the results needed to judge observed differences in attention.

13. Why This Trial Matters Statistically

This experiment is statistically interesting because it distinguishes several dimensions of attention rather than treating attention as a single outcome. Dwell time measures duration of looking, while fixation count and time to first fixation describe other aspects of gaze behavior. Self-reported attention, perceived message effectiveness and understandability address participant-reported responses. These measures can answer different questions, and their values should not be treated as interchangeable.

The study also raises a design question that matters for interpretation: how label formats are compared. The registry record describes a single-group model and explicitly cautions that the arms are not a like-for-like control comparison. That distinction is consequential. A label being called a control does not, by itself, establish that comparisons with it are protected from bias. Clear reporting of exposure patterns and analysis methods would help readers understand what a contrast represents.

The stated interest in English language proficiency is another potentially important analytic question. The study aims to explore moderation of the icon-versus-text-only effect on attention. General statistical explanation: moderation asks whether an association or contrast differs across levels of another characteristic. To interpret such an analysis, readers need the estimated interaction or subgroup contrasts, their uncertainty, and an understanding of whether the analysis was prespecified. Those results and details are not reported in the registry record.

The registry record identifies a broad analysis set—seven outcomes and 42 analyses—without explaining the multiplicity strategy. Transparent reporting of which analyses were primary and how uncertainty was handled would be important when interpreting multiple outcomes and contrasts. Since the registry record does not report numerical findings, it cannot establish whether any observed pattern was large, precise or consistent across measures.

The statistical value of the record is thus primarily descriptive: it documents the question, measurement approach, and design cautions. The outcome data and analytic details needed to evaluate the evidence are not reported in the registry record.

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.

The main limitation for statistical interpretation is that numerical results for the primary endpoint are not reported in the registry record. No observed dwell-time mean or standard deviation, label contrast, confidence interval or p-value is available. Results for the listed secondary outcomes are also not reported. The research aims can therefore be described, but the observed attention patterns and their precision cannot be evaluated.

The study's comparison structure is another limitation. Allocation is recorded as NA, the model is SINGLE GROUP, and the record states that this is not a randomized comparison and that arms are not a like-for-like control comparison. Although the barcode label is described as a control, the available design information does not establish a randomized control contrast. The registry record does not report the exposure sequence or enough detail to determine how participant-level observations relate to the listed labels.

The record reports enrollment of 63, but does not identify the analysis population or give outcome-specific denominators. Missing-data handling, exclusions, and sensitivity analyses are not reported in the registry record. As a result, it is not possible to assess whether all enrolled participants contributed to each endpoint or whether missing measurements could affect interpretation.

The registry record lists seven outcomes and 42 analyses but does not describe the analysis plan, the role of each analysis, or any multiplicity adjustment. It also does not provide the model, covariate adjustments, or methods for the English language proficiency moderation question. These omissions limit assessment of analytic choices and the potential for selective emphasis.

Finally, the primary outcome is a gaze-duration measure. It represents visual attention as defined by the study, but the record does not establish that it measures comprehension, later food choices, or other outcomes. Results for the separate understandability and perceived effectiveness measures are not reported.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Visual Attention to Text and Pictorial Food Labels: An Eye Tracking Experiment — NCT05958888.
• Registry record last updated 2024-08-13; status last verified 2023-10.
• Results first posted 2024-08-13.
• 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

NCT05958888 is a completed, single-group eye-tracking experiment sponsored by University of North Carolina, Chapel Hill, with enrollment of 63. The registry record lists text-only, icon, pictorial and barcode food labels, and describes an image of a soup can with four labels. The primary outcome is dwell time on the front-of-package sodium label, measured in seconds; listed secondary outcomes include gaze measures and self-reported attention and perceptions.

The study aims include examining attention across label formats and exploring moderation by English language proficiency. The record cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. Numerical primary and secondary outcome results, analysis populations, missing-data methods, and the statistical analysis plan are not reported in the registry record. The adverse-event entries list zero serious and zero other events for each of the four groups.