First Paper Friday: Soo Ji Serisse Choi

University of Michigan School of Information PhD candidate Soo Ji Serisse Choi has published her first paper as a UMSI student. The paper introduces WalktoJoy, a message-based mobile health app - or mHealth - intervention designed to help adults build more positive feelings toward physical activity. 

Her paper, “Improving Affective Associations With Physical Activity via a Message-Based mHealth Intervention (WalkToJoy): Proof-of-Concept Study” is published in the August issue of the Journal of Medical Internet Research in collaboration with Pei-Yao Hung, Mengyun Liu, Walter Dempsey, and UMSI professors Mark Newman and Predrag Klasnja. 

The study involved a six-week remote trial with adults aged 40 and older and tested whether prompts like animated walking suggestions could shift how participants felt about walking. Results showed meaningful improvements in participant attitudes towards walking. 

“This project started with a simple question: how can we help people not just be more active for a short time, but develop a more intrinsically positive relationship with physical activity?” Choi says. “In a 6-week study with adults over 40, we found that revising these associations can encourage more enjoyable, self-motivated engagement with physical activity.” 

In the future, Choi says she hopes to continue exploring how to foster lasting, meaningful behavior change. She is currently entering her fourth year in UMSI’s PhD program, where is advised by UMSI professors Mark Newman and Predrag Klasnja. She is expected to graduate in May 2027. 

Her research interests focus on mobile health technologies and how they can support middle-aged adults and older adults. Before joining UMSI, Choi earned her bachelor of fine arts at the Art Institute in Chicago, where she specialized in visual communication design and sculpture. She first came to UMSI for her master’s degree before continuing into the PhD program to further her research. 

At UMSI, Choi says she enjoys the diversity of perspective and the “community’s shared commitment to creating positive change.” 

“Being surrounded by people who bring different experiences and ideas has shaped my own work in meaningful ways,” she says. 

Read “Improving Affective Associations With Physical Activity via a Message-Based mHealth Intervention (WalkToJoy): Proof-of-Concept Study” in the August issue of the Journal of Medical Internet Research. The paper is authored by UMSI PhD candidate Soo Ji Serisse Choi, Pei-Yao Hung, Mengyun Liu, Walter Dempsey, and UMSI professors Mark Newman and Predrag Klasnja. 

Background: Traditional mobile health interventions for physical activity (PA) primarily rely on reflective self-regulatory processes, often neglecting the role of affective associations in sustaining long-term engagement. The WalkToJoy intervention addresses this gap by applying the affective-reflective theory to enhance intrinsic motivation for PA among adults aged ≥40 years through affective message framing, evaluative conditioning, and belief updating.

Objective: This proof-of-concept study evaluated the feasibility of the message-based WalkToJoy intervention package and examined the impact of its 3 components—walking suggestion prompts, salience messages, and planning prompts—on affective and behavioral outcomes related to walking.

Methods: We conducted a fully remote, 6-week full factorial experiment with an embedded microrandomized trial (MRT) involving 49 adults aged ≥40 years. Statistical analyses, including paired t tests and generalized estimating equations, assessed pretest-posttest changes and the effects of smile-inducing walking suggestion prompts with short animated images (GIF images), salience messages, and planning prompts on weekly affective measures and daily step counts. In addition, MRT analyses evaluated the proximal effects of these components. Poststudy interviews were thematically analyzed to contextualize participants’ experiences and engagement with the intervention.

Results: Significant pretest-posttest improvements were observed across affective outcomes on a 7-point Likert scale—affective attitudes improved by 0.547 points (P<.001), affective valuations improved by 0.718 points (P<.001), affective reflection improved by 0.692 points (P<.001), and anticipated affect improved by 0.692 points (P<.001). While the average daily steps showed a nonsignificant pretest-posttest increase of 80 steps (P=.79), further analysis revealed an increase of 506 steps (P=.07) when comparing baseline to the average of weeks 4 to 6. Among the intervention components, GIF prompts significantly increased anticipated affect by 0.345 points (P=.046) and average daily step count by 1834 steps (P=.05) compared to identical text-only prompts. However, MRT analysis found no significant increase in 4-hour step counts following the walking suggestion prompts (P=.55), which was explained by qualitative findings suggesting that participants interpreted messages as flexible day-long reminders rather than immediate calls to action. Salience and planning prompts did not yield substantial quantitative effects but were positively received by participants for promoting mindfulness and personalized engagement.

Conclusions: The WalkToJoy intervention is a feasible and promising approach for improving affective associations with walking. Walking suggestion prompts were particularly effective in boosting engagement and mitigating message fatigue, highlighting the potential of affect-driven interventions to enhance PA motivation and adherence.

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Learn more about Soo Ji Serisse Choi’s research by visiting her UMSI profile. 

Apply to UMSI’s PhD in Information.