Food Choice
Conditions
Brief summary
The pervasiveness of high-calorie, nutrient-poor snacks in the environment is believed to have contributed to the epidemic levels of obesity and cardiometabolic disease in the U.S. This project tests whether a novel snack vending machine system that uses brief time delays to reduce the immediacy of reward from unhealthy snacks will improve the healthfulness of snack choices. If successful, this project will identify a new environmental intervention that could contribute substantially to obesity and cardiometabolic disease prevention efforts in schools, worksites, and other settings.
Detailed description
Environmental interventions that address the high availability of unhealthy snacks in the environment are needed to prevent a large projected increase in the incidence of obesity and cardiometabolic disease in the U.S. Prior studies from the investigators group and others suggests that the human preference for immediate gratification from food drives dietary overconsumption, but this knowledge has not yet translated to more effective dietary intervention strategies. This project tests whether a novel snack vending machine system that uses brief time delays to reduce the immediacy of reward from unhealthy snacks will improve the healthfulness of snack choices. This study uses an experimental design to compare brief time delays, two forms of 25% differential pricing, and time delays combined with both forms of 25% differential pricing on their ability to increase purchasing of healthy snacks. Test machines will be placed in existing, high-volume vending locations, and each of these five experimental conditions will run for roughly four weeks. Additionally, baseline purchasing under no intervention will be monitored for four weeks before and four weeks after the five experimental conditions. Specific Aim 2 compares the effects of these five interventions against baseline on the proportion of total vending sales from healthy snacks. Specific Aim 3 tests whether time delays or differential pricing harm overall vending machine sales in the test machines. This study not only tests a compelling theory about the effects of time delays and immediate reward on food choice, but evaluates the efficacy and feasibility of a novel intervention to improve the healthfulness of snack choices in worksites, schools, and other settings.
Interventions
OTHERTime delays on delivery of less healthy snacks
OTHER25%/$0.25 discount on healthy snacks
OTHER25%/$0.25 tax on less healthy snacks
Sponsors
Rush University Medical Center
Study design
Observational model
ECOLOGIC_OR_COMMUNITY
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Healthy volunteers
Yes
Inclusion criteria
* Not applicable
Exclusion criteria
* Not applicable
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Proportion of Healthy Snacks Purchased | 28 weeks per vending location | For each experimental condition, we will calculate the proportion of healthy vs unhealthy snacks sold over 4 weeks. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Total Daily Vending Revenue in US$/Day | Number of days per condition were as follows - Baseline: 119 days, Discount only: 59 days, Delay only: 68 days, Delay + Discount: 49 days, Tax only: 73 days, Delay + Tax: 60 days | Total vending machine revenue under each condition |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Baseline 1 Snacks sold under equal pricing, no delays. Baseline 1 was always the first condition at all vending sites. | 0 |
| Discount Only Healthier snacks sold at 25% or $0.25 discount, no delays
25%/$0.25 discount on healthy snacks | 0 |
| Delay Only Less healthy snacks sold at equal pricing with delays
25-second time delays on delivery of less healthy snacks | 0 |
| Delay + Discount Healthy snacks sold at 25% or $0.25 discount, plus delays on less healthy snacks
25-second time delays on delivery of less healthy snacks
25%/$0.25 discount on healthy snacks | 0 |
| Tax Only Less healthy snacks sold at 25% or $0.25 higher price, no delays
25%/$0.25 tax on less healthy snacks | 0 |
| Delay + Tax Less healthy snacks sold at 25% or $0.25 higher price, plus delays
Time delays on delivery of less healthy snacks
25%/$0.25 tax on less healthy snacks | 0 |
| Baseline 2 Snacks sold under equal pricing, no delays. Baseline 2 was always the last condition at all vending sites. | 0 |
| Total | 0 |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk | EG004 affected / at risk | EG005 affected / at risk |
|---|---|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 |
| other Total, other adverse events | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 |
| serious Total, serious adverse events | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 | 0 / 0 |
Outcome results
Primary
Proportion of Healthy Snacks Purchased
For each experimental condition, we will calculate the proportion of healthy vs unhealthy snacks sold over 4 weeks.
Time frame: 28 weeks per vending location
Population: In this table, each vend is treated as an analyzed participant. No data were collected from individual human subjects. Analyses included all available data on healthy and regular snack vends. Data from Baseline 1 and Baseline 2 were combined into a single arm/group (Baseline) in statistical analyses.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Baseline | Proportion of Healthy Snacks Purchased | .403 proportion of vends from healthy snacks |
| Discount Only | Proportion of Healthy Snacks Purchased | .431 proportion of vends from healthy snacks |
| Delay Only | Proportion of Healthy Snacks Purchased | .429 proportion of vends from healthy snacks |
| Delay + Discount | Proportion of Healthy Snacks Purchased | .465 proportion of vends from healthy snacks |
| Tax Only | Proportion of Healthy Snacks Purchased | .542 proportion of vends from healthy snacks |
| Delay + Tax | Proportion of Healthy Snacks Purchased | .501 proportion of vends from healthy snacks |
Secondary
Total Daily Vending Revenue in US$/Day
Total vending machine revenue under each condition
Time frame: Number of days per condition were as follows - Baseline: 119 days, Discount only: 59 days, Delay only: 68 days, Delay + Discount: 49 days, Tax only: 73 days, Delay + Tax: 60 days
Population: The unit of analysis is vending revenue per day ($/day). Data from Baseline 1 and Baseline 2 were combined into a single arm/group (Baseline) in this analysis.
| Arm | Measure | Value (MEAN) | Dispersion |
|---|---|---|---|
| Baseline | Total Daily Vending Revenue in US$/Day | 45.4 $/day | Standard Deviation 31.6 |
| Discount Only | Total Daily Vending Revenue in US$/Day | 42.1 $/day | Standard Deviation 33.3 |
| Delay Only | Total Daily Vending Revenue in US$/Day | 44.6 $/day | Standard Deviation 27.7 |
| Delay + Discount | Total Daily Vending Revenue in US$/Day | 35.9 $/day | Standard Deviation 21 |
| Tax Only | Total Daily Vending Revenue in US$/Day | 46.4 $/day | Standard Deviation 35.6 |
| Delay + Tax | Total Daily Vending Revenue in US$/Day | 51.9 $/day | Standard Deviation 66.5 |