Understanding Mechanisms of Health Behavior Change

Study Overview
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Brief Summary
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This research seeks to examine psychological factors that may impact relationship between incentives and health behavior engagement, specifically fruit and vegetable consumption. Additionally, it will compare the impact of two different incentive schedules on behavior engagement, one providing immediate rewards (i.e. rewards received on a daily basis) and another providing delayed rewards (i.e. rewards received at the end of the study period), with a control condition in which no rewards are offered. Study participants will provide reports of their fruit and vegetable consumption each day for three weeks, and in the two incentive conditions, they will receive small monetary rewards for their fruit and vegetable consumption. Following the three week reporting and reward period, participants will complete two additional assessments, measuring psychological constructs and behavior engagement following the cessation of rewards. The study will also examine how cognitive and anthropomorphic factors may contribute to intervention response and the effects on psychological constructs.

Official Title
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Understanding Mechanisms of Health Behavior Change

Conditions
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Overweight and Obesity, Diet Modification, Incentives

Intervention / Treatment
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* Behavioral: self-monitoring
* Behavioral: daily monetary incentives
* Behavioral: delayed lump sum monetary incentives


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Consume fewer than 3 servings/day of fruits and vegetables Daily access to internet for 3 weeks following baseline session Have or are willing to create an account on PayPal BMI greater than or equal to 25, from self-reported height and weight Exclusion Criteria: -

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Self-Monitoring Control<br>Daily tracking of fruit and vegetable consumption | Behavioral: self-monitoring<br>* recording fruit and vegetable consumption<br>|
| Experimental: Daily Incentives<br>Incentives for fruit and vegetable consumption delivered daily | Behavioral: self-monitoring<br>* recording fruit and vegetable consumption<br>Behavioral: daily monetary incentives<br>* daily payments for consuming fruits and vegetables<br>|
| Experimental: Delayed Lump Sum Incentives<br>Incentives for fruit and vegetable consumption delivered in a lump sum at the end of the intervention | Behavioral: self-monitoring<br>* recording fruit and vegetable consumption<br>Behavioral: delayed lump sum monetary incentives<br>* lump sum payments for consuming fruits and vegetables<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fruit and vegetable consumption, servings per week |  | 3 Weeks | 
| Fruit and vegetable consumption, servings per week |  | 5 Weeks | 
| Perceived behavioral control scale score |  | 3 Weeks | 
| Perceived behavioral control scale score |  | 5 Weeks | 
| Attitude scale score |  | 3 Weeks | 
| Attitude scale score |  | 5 Weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intrinsic motivation scale score |  | 3 Weeks | 
| Intrinsic motivation scale score |  | 5 Weeks |