JMIR Publications

ABSTRACT

Background:

The use of digital technology enabled the investigation of stress in everyday life. However, ambulatory research depends on the natural occurrence of stressful situations while most standardized stress inductions rely on cost- and labor-expensive laboratory experiments, which are limited in their infrequent applicability.

Objective:

We developed the Salzburg Mobile Stress Induction (SMSI), a newly conceptualized toolbox including six different stress-inducing paradigms (Matrices, Cube Net, Arithmetic, Number Series, Word Scramble, and Word Pair) and one control paradigm (Caesar Cipher) which are based on cognitive performance tests. These seven tests are intended to provide researchers with an open access, standardized method to repeatedly induce stress in an ambulatory setting.

Methods:

We recruited university students from a local university and via a crowdsourcing platform for a preregistered ambulatory study. After an initial web-based survey, participants performed the seven SMSI tests in randomized order over 4 days on their smartphones via the m-Path app. By comparing the stress-inducing tests with the control test, we investigated changes in momentary negative and positive affect from baseline (t0) to between (t1) and after (t2) each test using the International Positive and Negative Affect Schedule Short Form.

Results:

A total of 100 participants (60/100 women; mean age 24.43 years, SD=6.21; 69/100 local sample; 31/100 crowdsourcing sample) completed all seven tests of the SMSI. Participants’ negative affect significantly increased during all six stress-inducing tests compared to the control test from t0 to t1 (Ps<.001) as well as to t2 (Ps<.001) with medium to large effect sizes (ηp²s=.10 to .30). Post-hoc pairwise comparisons showed significant increases of negative affect during all stress-inducing tests from t0 to t1 (Ps<.001) and t2 (Ps<.001) and a slight increase in the control test from t0 to t2 (P=.006). Reported positive affect significantly differed between the stress-inducing tests and the control test from t0 to t1 (Ps<.001) and to t2 (Ps<.001) with medium to large effect sizes (ηp²s=.14 to .33). Post-hoc pairwise comparisons revealed a significant increase in positive affect in the control test from t0 to t1 (P<.001) as well as to t2 (P<.001) and varying significant decreases to non-significant changes in the stress-inducing tests over time (Ps>.99 to <.001).

Conclusions:

The SMSI presents novel and easy-to-implement standardized stress induction procedures to repeatedly evoke stress in ambulatory research. We discuss new opportunities for positive (eu-)stress inductions and outline subsequent validation studies combining physiological stress assessment and ambulatory methods. The development of additional language versions of the SMSI is illustrated.