Structured Exploration vs. Generative Flexibility: A Field Study Comparing Bandit and LLM Architectures for Personalised Health Behaviour Interventions

Fuente: arXiv
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Autori principali: Hofer, Dominik P., Song, Haochen, Islambouli, Rania, Hawkins, Laura, Bhattacharjee, Ananya, Franklin, Meredith, Williams, Joseph Jay, Smeddinck, Jan D.
Natura: Preprint
Pubblicazione: 2026
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author Hofer, Dominik P.
Song, Haochen
Islambouli, Rania
Hawkins, Laura
Bhattacharjee, Ananya
Franklin, Meredith
Williams, Joseph Jay
Smeddinck, Jan D.
author_facet Hofer, Dominik P.
Song, Haochen
Islambouli, Rania
Hawkins, Laura
Bhattacharjee, Ananya
Franklin, Meredith
Williams, Joseph Jay
Smeddinck, Jan D.
contents Behaviour Change Techniques (BCTs) are central to digital health interventions, yet selecting and delivering effective techniques remains challenging. Contextual bandits enable statistically grounded optimisation of BCT selection, while Large Language Models (LLMs) offer flexible, context-sensitive message generation. We conducted a 4-week study on physical activity motivation (N=54; 9 post-study interviews) that compared five daily messaging approaches: random templates, contextual bandit with templates, LLM generation, hybrid bandit+LLM, and LLM with interaction history. LLM-based approaches were rated substantially more helpful than templates, but no significant differences emerged among LLM conditions. Unexpectedly, bandit optimisation for BCTs selection yielded no additional perceived helpfulness compared with LLM-only approaches. Unconstrained LLMs focused heavily on a single BCT, whereas bandit systems enforced systematic exploration-exploitation across techniques. Quantitative and qualitative findings suggest contextual acknowledgement of user input drove perceived helpfulness. We contribute design suggestions for reflective AI health behaviour change systems that address a trade-off between structured exploration and generative autonomy.
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id arxiv_https___arxiv_org_abs_2603_06330
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Structured Exploration vs. Generative Flexibility: A Field Study Comparing Bandit and LLM Architectures for Personalised Health Behaviour Interventions
Hofer, Dominik P.
Song, Haochen
Islambouli, Rania
Hawkins, Laura
Bhattacharjee, Ananya
Franklin, Meredith
Williams, Joseph Jay
Smeddinck, Jan D.
Human-Computer Interaction
Artificial Intelligence
Behaviour Change Techniques (BCTs) are central to digital health interventions, yet selecting and delivering effective techniques remains challenging. Contextual bandits enable statistically grounded optimisation of BCT selection, while Large Language Models (LLMs) offer flexible, context-sensitive message generation. We conducted a 4-week study on physical activity motivation (N=54; 9 post-study interviews) that compared five daily messaging approaches: random templates, contextual bandit with templates, LLM generation, hybrid bandit+LLM, and LLM with interaction history. LLM-based approaches were rated substantially more helpful than templates, but no significant differences emerged among LLM conditions. Unexpectedly, bandit optimisation for BCTs selection yielded no additional perceived helpfulness compared with LLM-only approaches. Unconstrained LLMs focused heavily on a single BCT, whereas bandit systems enforced systematic exploration-exploitation across techniques. Quantitative and qualitative findings suggest contextual acknowledgement of user input drove perceived helpfulness. We contribute design suggestions for reflective AI health behaviour change systems that address a trade-off between structured exploration and generative autonomy.
title Structured Exploration vs. Generative Flexibility: A Field Study Comparing Bandit and LLM Architectures for Personalised Health Behaviour Interventions
topic Human-Computer Interaction
Artificial Intelligence
url https://arxiv.org/abs/2603.06330