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Dissertation Defense: From Measurement to Policy: Sugar-sweetened Beverages as a Public Health Nutrition Target

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Haylee Downey

Dissertation Defense: From Measurement to Policy: Sugar-sweetened Beverages as a Public Health Nutrition Target

Haylee Downey

Graduate Student, Translational Biology, Medicine, and Health
Graduate Research Assistant, Stein Lab, Fralin Biomedical Research Institute at VTC
April 17, 2026, at 10 a.m.
Room 1102, 4 Riverside Circle
Visit the Stein Lab

About this Dissertation

Sugar-sweetened beverages (SSB), or beverages with added caloric sweetener, have become a staple of the American diet with the industrialization of food. However, consuming SSB is associated with increased risk of diet-related chronic diseases, including cardiovascular disease and type 2 diabetes. Given these harms, accurate measurement of SSB intake and understanding ways to reduce SSB intake are needed to improve diet quality and prevent disease. SSB taxes are an effective way to reduce SSB purchasing. To further understand SSB taxes and purchasing, Downey, working with mentor Jeff Stein, developed an experimental marketplace, or a virtual storefront in study 1. Participants purchased less SSB when SSB were taxed, helping to validate the paradigm. In study 2, Downey used the experimental marketplace to examine how different tax bases, or sets of products taxed, influenced beverage purchasing. Taxes on SSB or both SSB and non-sugar sweetened beverages were similarly effective in reducing SSB purchasing. In study 2, Downey also examined if the effect of taxes on SSB purchasing depended on individual characteristics relevant to health equity, including household income and level of SSB intake, finding larger reductions for people who drink more SSB. In study 3, Downey examined the reliability of a tool to assess beverage intake across household income levels. Measurements were correlated across time for both income groups, but intake was significantly higher for the first measurement. Overall, this work contributes to better understanding of SSB as a target in public health nutrition, including development of measurement tools and evaluation of reduction policies.

More About the Candidate and Project

Education

Virginia Tech, Translational Biology, Medicine, and Health, Ph.D. Candidate

Utah State University, B.S., Psychology

Training

Graduate Research Assistant, Stein Lab, Fralin Biomedical Research Institute at VTC

Mentor

Jeff Stein, Ph.D., Assistant Professor and Interim Co-director, Center for Health Behaviors Research, Fralin Biomedical Research Institute at VTC

Committee Members

  • Brenda Davy, Ph.D., RDN, Professor, Department of Human Nutrition, Foods, and Exercise, College of Agriculture and Life Sciences
  • George Davis, Ph.D., Professor, Department of Agricultural and Applied Economics, Department of Human Nutrition, Foods, and Exercise, College of Agriculture and Life Sciences
  • Alexandra DiFeliceantonio, Ph.D., Assistant Professor and Interim Co-director, Center for Health Behaviors Research, Fralin Biomedical Research Institute at VTC

Publications

Book Chapter
Downey, H. & Stein, J. S. (accepted; in press). Delay discounting: A primer. In G. Madden & F. DiGennaro Reed (Ed.), APA Handbook of Behavior Analysis, Second Edition. American Psychological Association.

Journal Articles 
Downey, H., Epstein, L. H. & Stein, J. (2025). The Experimental Beverage Marketplace: Feasibility and preliminary validation of a tool to experimentally study sugar-sweetened beverage taxes and beverage purchasing. Appetite. https://doi.org/10.1016/j.appet.2024.107848

Downey, H., Alvarez, A., Ji, W., Lozano, A., Hanlon, A. & Stein, J. S. (2025). Perceived reward certainty in the assessment of delay discounting. Journal of the Experimental Analysis of Behavior. https://doi.org/10.1002/jeab.70044

Downey, H., Xu, S., Ahmadi, S., Shah, A., Brown, J. M., Bickel, W. K., Tegge, A. N., Fox, E. A. & Stein, J. S. (2025). What’s in a cue?: Using natural language processing to examine the content of episodic future thinking cues and the potential moderating role of cue characteristics on delay discounting. Health Psychology and Behavioral Medicine. https://doi.org/10.1080/21642850.2025.2510417

Aycinena, D., Baltaduonis, R., Downey, H., Fors, K. & Rentschler, L., (2025). Relative feedback response in competitive environments. Review of Behavioral Economics, 12(1). 49-67. http://dx.doi.org/10.1561/105.00000203

Osai, K., Dorsch, T., Bradford, K., Whiteman, S., Blazo, J. & Downey, H. (2025). All in the family: A collective case study of family influence on siblings’ experiences and outcomes in organized youth sport. Journal of Social and Personal Relationships. https://doi.org/10.1177/02654075251321377

Downey, H., Freitas-Lemos, R., Curran, K., Serrano, E. L., Davis, G. C., & Stein, J. S. (2023). COVID-19-related financial scarcity is associated with greater delay discounting but not probability discounting. Behavioural Processes, 211, 104928. https://doi.org/10.1016/j.beproc.2023.104928

Downey, H., Haynes, J. M., Johnson, H. M., & Odum, A. L. (2022). Deprivation has inconsistent effects on delay discounting: A review. Frontiers in Behavioral Neuroscience, 16, 787322. https://doi.org/10.3389/fnbeh.2022.787322

Odum, A. L., Becker, R. J., Haynes, J. M., Galizio, A., Frye, C. C. J., Downey, H., Friedel, J. E., & Perez, D. (2020). Delay discounting of different outcomes: Review and theory. Journal of the Experimental Analysis of Behavior. 113(3), 657-679. https://doi.org/10.1002/jeab.589.

Presentations

Downey, H., Bruckner, L., & Stein, J.S. (2025, November). Sweetened beverage taxes: Testing the effects of tax design across population subgroups using an experimental marketplace. Poster presented at the annual meeting of the American Public Health Association, Washington, DC.

Downey, H. & Stein, J.S. (2025, August). Effects of sweetened beverage taxes on beverage purchasing among households with and without children: An exploratory subgroup analysis from an online experimental marketplace study. Poster available virtually for the Healthy Eating Research & Nutrition and Obesity Policy and Research Evaluation Network Summer Speaker Series. Available at: https://nopren.ucsf.edu/her-nopren-student-posters-2025

Downey, H., Alvarez, A., Ji, W., Lozano, A., Hanlon, A. & Stein, J. S. (2025, May). Delay discounting and perceived reward certainty. Poster presented at the annual meeting of the Association for Behavior Analysis International, Washington, DC.

Downey, H. & Stein, J. S. (2024, May). An Experimental Tool for Studying Beverage Purchasing Behavior: Initial Development and Validation. Poster presented at the annual meeting of the Association for Behavior Analysis International, Philadelphia, PA.

Downey, H. & Stein, J. S. (2024, May). Further Examining the Relationship Between Delay Discounting and Body Mass Index. Poster presented at the annual meeting of the Association for Behavior Analysis International, Philadelphia, PA.

Downey, H. & Stein, J. S. (2023, August). The Experimental Beverage Marketplace: A promising tool to study how individuals respond to sugar sweetened beverage taxes. Poster available virtually for the Healthy Eating Research & Nutrition and Obesity Policy and Research Evaluation Network Summer Speaker Series. Available at: https://nopren.ucsf.edu/her-nopren-student-poster-presentations-2023

Downey, H., Freitas-Lemos, R., Curran, K. M., Serrano, E. L., Davis, G. C., & Stein, J. S. (2023, May). COVID-19-Related Financial Scarcity is Associated with Greater Delay Discounting But Not Probability Discounting. Poster presented at the annual meeting of the Association for Behavior Analysis International, Denver, CO.

Downey, H.,& Stein, J. S. (2023, May). Development of a discounting task for choice between qualitatively different food rewards. Poster presented at the annual meeting of the Association for Behavior Analysis International, Denver, CO.

Stein, J. S., Tegge, A. N., Downey, H., Brown, J. M. & King, M. J. (2023, May). Simultaneous assessment of delay, probability, and combined delay × probability discounting: Extensions of a multiplicative model of discounting using Effective Delay 50. In Jeff Stein (chair), Methodological Advancements in the Study of Discounting Processes: Modeling More Complex, Naturalistic Choices and Exploring Opportunities in Longitudinal Big Data. Symposium to occur at the annual meeting of the Association for Behavior Analysis International, Denver, CO.

Downey, H., Haynes, J. M., Galizio, A., Perez, D., & Odum, A. L. (2020, February). Delay discounting: State and trait influences. Oral presentation given at the Utah Conference for Undergraduate Research, Logan, UT.

Odum, A. L., Haynes, J. M., Galizio, A., Downey, H., & Perez, D. (2019, November). Why do we disregard delayed outcomes? Invited address given at the annual meeting for the Georgia Association for Behavior Analysis, Athens, GA.

Odum, A. L., Haynes, J. M., Galizio, A., Downey, H., & Perez, D. (2019, October). Delay discounting: Why do we do things we regret? Keynote address given at the annual meeting for the Mexican Association for Behavior Analysis, Mexico City, Mexico.

Odum, A. L., Haynes, J. M., Galizio, A., Downey, H., & Perez, D. (2019, October). Why do we disregard delayed consequences? Invited address given at the annual meeting for the Nevada Association for Behavior Analysis, Reno, NV.

Downey, H., Becker, R. J., & Odum, A. L. (2019, May). Poor stimulus control in multiple frequency-dependent schedules of reinforcement in pigeons. Poster presented at the annual meeting of the Society for the Quantitative Analysis of Behavior, Chicago, IL. 

Becker, R. J., Perez, D., Downey, H., & Odum, A. L. (2019, May). Past behavior as a stimulus: Differential control of operant variability in pigeons. In Weizhi Wu (Chair), Translational Research on Conditional Discriminations. Symposium presented at the annual meeting of the Association for Behavior Analysis International, Chicago, IL.

Downey, H., Becker, R. J., & Odum, A. L. (2019, March) Developing a computer game to measure delay discounting. Poster presented at Research on Capitol Hill, Salt Lake City, UT.

  • Innovative Student Research Dissertation Grant, Society for the Advancement of Behavior Analysis (2024)
  • Joseph V. Brady Significant Research Contribution Award, Society for the Experimental Analysis of Behavior (2023)
  • Graduate Research Development Program Grant, Virginia Tech (2022)

Science-Related Volunteering and Outreach

  • Bodies and Bites (Role: group leader) - Led hands-on lessons to teach elementary students about topics in physiology and STEM. 04-21-2022, 10-26-2023
  • Flip the Fair (Role: presenter, volunteer) - Created tri-fold poster and presented work to 5th graders, who judge the posters. 09-28-2023, 09-26-2024
  • Brain Awareness Week (Role: presenter) - Presented neuropsychology topics to high school students. 03-14-2023, 03-24-2024
  • Roanoke County Public Schools Science Fair (Role: judge) 02-11-2023, 02-24-24

Ad-hoc Journal Peer Review 

  • Primary reviewer: Journal of Neuroscience, Psychology, and Economics
  • Co-reviewer: BMJ Nutrition, Prevention & Health; Frontiers in Public Health; Journal of Behavioral Decision Making; Journal of the Experimental Analysis of Behavior; Psychological Record