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Sue Frantz

Do Fitness Trackers Work?

Posted by Sue Frantz Sep 21, 2016

When covering research methods or as a research methods boost in health psych in Intro, ask your students, “Do fitness trackers, like Fitbit, work? If you were a psychological scientist trying to answer this question, how would you do it?”


Give students a couple minutes to think about this on their own. Next, ask students to work in pairs or small groups to design an experiment that would help answer this question.


As you circulate among the groups, make sure the groups are answering the question “Do fitness trackers work… at doing what?”


As discussion is winding down, bring the class back together and ask for groups willing to volunteer their experimental designs.


There should be some sort of random assignment to wearing a fitness tracker or not. Ask students why? [Because if you compared existing users with existing non-users, the users may already be more motivated to engage in physical activity.]

Ask students to identify the independent variable [fitness tracker usage] and the experimental condition [fitness tracker] and control condition [no fitness tracker]. How long did students think participants should use/not use a fitness tracker to ensure a fair test? Why that amount of time?


Ask students to identify the dependent variable(s) [perhaps weight loss].


With class discussion on the design wrapping up, share with students the results of such a study (Jakicic,, 2016). Participants (470 of them) were six months into a 2-year weight-loss study when they were randomly assigned to either wear a fitness tracker that included a website for monitoring diet or self-monitor exercise and diet via a website (74.5% completed the study; every six months, participants were given $100). Note that this study did not have a no-treatment control group.


Ask students to predict the results by a show of hands or via an audience response system.

A. Fitness-tracker users lost the most weight

B. Self-monitors lost the most weight

C. Fitness-tracker users and self-monitors lost about the same amount of weight.


Ready for the results? Those assigned to wear fitness trackers lost 3.5 kg (7.7 lbs). Those assigned to self-monitor lost 5.9 kg (13 lbs). There were no differences in the groups at the 6-month mark, the point in the study where they were randomly assigned to wear the fitness tracker or self-monitor. But at the next three check-ins (12 months, 18 months, and 24 months), the self-monitoring group had always lost more weight. Did your students guess right? Were they surprised by the results?


Some explanations for these results are offered in this NPR story. But before you share these with students, ask students to generate some hypotheses as to why the self-monitoring group lost more weight than the fitness-trackers. If time allows, give students a couple minutes to think on their own before sharing in pairs or small groups.  Ask student volunteers to report out their hypotheses. Write the hypotheses where students can see them. If you’d like to send students off with a take-home assignment, assign students to design an experiment (but not conduct it!) that would test one of the student-generated hypotheses. Students should identify their independent and dependent variables and anything else they would do that would eliminate confounding variables. You can either let students choose the hypothesis, or assign hypotheses by last name, e.g., “If you’re last name begins with A through F, you have hypothesis 1.” Students can submit as a written assignment, or if you have time at the beginning of the next class, give students an opportunity to share their designs with each other, and then take a few minutes to ask volunteers to share their designs.




Jakicic, J. M., Davis, K. K., Rogers, R. J., King, W. C., Marcus, M. D., Helsel, D., . . . Belle, S. H. (2016, September 20). Effect of wearable technology combined with a lifestyle intervention on long-term weight loss: The IDEA randomized clinical trial. Retrieved from

This extinction illusion (Hermann grid variation) has been making the rounds on social media courtesy of a Facebook post by psychological scientist Akiyoshi Kitaoka. There are 12 black dots in this grid. Most people cannot see them all at once.

The illusion itself first made an appearance in a 2000 journal article by Ninio & Stevens. Check out their paper for other illusions.

Ninio Extinction Illusion

The larger lesson for your students: Our senses, including vision, allow our brains to create a representation of the world around us. Our senses do not allow our brains to generate a perfect replication of the world.


For students who want to know why the illusion works, well, that’s a little more challenging. The short answer is that our retinas are hard-wired to send the clearest, sharpest signals to the brain. Receptor cells that get the strongest signal block out the weaker signals. Those dots in the periphery get blocked by the grey that surround them thanks to the sparser rods in the periphery.


For the longer answer, read up on lateral inhibition. Wikipedia provides a nice summary. (Yes, lateral inhibition is also used to explain Mach bands.)


If you want to wade into this even deeper with your students, Wesley Jordan (St. Mary’s College of Maryland) has created a class activity that should help students understand lateral inhibition.



Ninio, J. & Stevens, K.A. (2000). Variations on the Hermann grid: An extinction illusion. Perception, 29, 1209-1217.

Years ago, as a young instructor, I didn’t have the tools to help my struggling students who came to my office for studying advice. I had a clear idea of what “studying” was since I had done it for so long, but I don’t know if it’s that I couldn’t put words to what I did to study or if I assumed that everyone did the same thing when “studying,” and that if that didn’t work, I didn’t know what would. In any case, over time, I got better at my advice – test yourself, space out your studying, for example.


One term I had a student who earned a perfect score on an exam. Students in the class knew somebody did, and they asked who it was. I said I couldn’t reveal the person’s name, but that person can if so desired. My perfect-score student immediately said, “I did! And I’m proud of it.” The other students began peppering her with some version of “How did you do it!” She explained that she spent time every day on the class. She read the textbook, took notes, merged her textbook notes with her class notes, thought of examples, tested herself over what she was learning. Students started exclaiming, “Oh! I don’t want to do all of that!” Her response? “Then you don’t get an A.”


Learning is hard work. There’s no way around it. For students who are willing and able to put in the hard work, I want them to use effective, research-based study techniques. Unfortunately, students may not know what those research-based study techniques are. Some of the techniques students use may be a complete waste of time. Gurung, Weidert, and Jeske (2010) asked 120 students to complete a questionnaire on 35 different study behaviors. The behaviors that correlated positively with the students’ final exam scores: “attended every class,” “answered every question in the study guide,” “used practice exams to study,” and “was able to explain a problem or phenomenon using the material.” Behaviors that correlated negatively with exam scores: “after class, I looked over my notes to check for and fill in missing information,” “highlighted the most important information in each chapter to review later,” “reviewed the chapter after the lecture on that topic,” “asked… a classmate/friend to explain material I didn’t understand,” and “asked the professor or TAs for additional materials.” Interestingly, when they looked at just the top half of exam performers, only one correlation remained. Those who reported highlighting as a study strategy scored lower than those who did not. Highlighting is easy to do – it’s too easy to do. It doesn’t require deep processing; it’s a very shallow process. But at the end, with words highlighted, it’s easy to fool oneself into thinking studying was accomplished. Highlighting is really just coloring – and there are reasons coloring is relaxing: it takes little to no cognitive effort.


Now, how about some advice on how to study? Yana Weinstein (UMass Lowell) and Megan Smith (Rhode Island College) of the blog have created a wonderful set of posters (slides and sticker templates) to help students learn how to study better. The strategies: spaced practice, retrieval practice, elaboration, interleaving, concrete examples, and dual coding. Side note: I love the use of the very specific word practice instead of the fuzzier word study. Elliott Hammer (2016) reports that “I’m also trying as of late to drop the word ‘study’ from my vocabulary in favor of ‘practice. It’s difficult to get students to be more active in their approach, and I want them to get beyond simply trying to read and call that studying. I don’t have data showing that the switch is working, but it feels more genuine.”


To get your students to dive into these learning strategies, after covering the memory chapter, ask students to explain why each strategy is effective based on the concepts and research covered in their reading. This makes a nice out-of-class assignment, but it would also work well done in class with small groups. Give each small group the set of posters to explain the effectiveness of each. After discussion wanes, ask a group to report out on one of the posters; give other groups an opportunity to add to the conversation. Move onto another group, and ask them to report out on a different poster. Continue until all of the posters have been covered. If you use a classroom response system, ask students if they currently use the study strategy and whether they plan to use it in the future.


Or you could do a jigsaw classroom. Divide the class into 6 groups of at least 6 members each (or 12 groups of at least 6 members or some other multiple of 6, depending on your class size) and give each group a different poster. (For smaller classes, use multiples of 3 and give each group 2 posters). After each group identifies why the strategy is effective (using the concepts learned in the memory chapter), break apart the groups so that at least one person from each group now forms a new group. Ask each new group member to share the strategy on their poster and explain why the strategy is effective.


Bonus: Use the Gurung, (2010) study as examples when you cover correlations in the research methods chapter. Or use it here in the memory chapter to reinforce correlations. And then ask students which learning strategy is being used in the practice of learning correlations.



Gurung, R. A., Weidert, J., & Jeske, A. (2010). Focusing on how students study. Journal of the Scholarship of Teaching and Learning, 10(1), 28-35.

Hammer, E. (2016, July 31). I’m a member of STP and this is how I teach. Retrieved from