Exploring the influence of testimonial source on attitudes towards e-mental health interventions among university students: Four-group randomized controlled trial

Electronic mental health services (eMHSs) offer additional options for the dissemination of psychological interventions for university students. Still, many university students are reluctant to use eMHSs. Narrative messages may help increase the awareness and acceptance of quality-approved programs. However, little is known about the usefulness of narrative messages to improve attitudes towards eMHSs. In this experiment, we thus aimed to explore in how far different ways of targeting information to students affect their attitudes towards eMHSs for stress prevention and therapy, and to identify potential determinants of attitude change. N = 451 students (Mean = 32.6 years, SD = 10.2, 75% female, 7% with eMHS experience) were randomly assigned to one of four study arms involving information designed to induce different levels of perceived similarity. While the active control condition only received general information (arm 1, “information only”, n = 116), the other experimental arms were additionally exposed to testimonials on specific eMHSs either addressing an unspecified audience (arm 2, n = 112), employees (arm 3, n = 115) or working university students (arm 4, n = 108). Two-way ANOVA revealed no impact of information on the alteration of attitudes towards eMHSs for stress coping (d = 0.20). Only a small effect of target-group specific testimonials on attitudes towards online therapies was identified at post-intervention (d = 0.29). Regression analyses demonstrated significant influences of source credibility and perceived similarity on attitudes for preventative eMHSs (ps<0.01), as well as a partial mediation effect of perceived similarity in favor of testimonials targeted to students (95% CI [0.22, 0.50]). Overall, this study indicated no meaningful impact of information on attitudes and limited evidence for benefits of tailored narrative messages. Since attitudes were already positive at baseline, further research with a representative student sample mimicking real-world decision scenarios is needed to gain an in-depth understanding of acceptance-facilitating message features that may contribute to promote the adoption of evidence-based eMHSs.


Additional information and testimonials (IGs only)
At first, participants in the three IGs read the following passage in which the name of the eMHS (X) and the provider (name of university; Y) was adapted to the IG: (…) "⦋ X ⦌ (⦋ Y ⦌) offers evidence-based and professionally guided internet-based training programs in areas such as "stress", "resilience", and "depression/anxiety." *** *** IG 1: X="MH-Online" (Y=Albert-Ludwigs-Universität Freiburg); IG 2: X="The GET.ON Institute" (Y=Leuphana Universität Lüneburg); IG 3: X= "StudiCare" (Y=Friedrich-Alexander-Universität Erlangen) In the condition receiving testimonials for GET.ON (IG2), we added a sentence to suggest a broader audience than for StudiCare (IG3): "Participation is open for various social groups, e.g. employed persons, trainees, students, retired persons." Textbox S2 shows additional information on eMHSs presented to the three IGs (X = name of the eMHS program).

Supplementary Textbox S2. Introduction to eMHSs in the IGs.
"These online trainings consist of 6 consecutive one-hour sessions. You can accompany the online sessions with an app that allows for daily use. Additionally, you may receive personal coaching sessions. The training program aims to help you regain productivity. The resiliencetraining program includes sessions on self-efficacy, optimism, relationships, and self-care. During the stress management training programs, participants learn to identify personal issues, practice coping mechanisms, apply problem-solving techniques, and learn how to manage difficult emotions.
Individuals who have participated in ⦋ X ⦌'s training programs were asked to relate their experiences:" Next, three testimonials were shown per IG, as shown in the Textboxes S3 to S5.

Supplementary Textbox S3. Testimonials for "MH-Online" (IG1).
"This internet-based therapy has really helped me. The training program and the contact with my therapist worked well." (Petra Z., 35) "My experience was positive. I would recommend MH-Online to others." (Sebastian L., 46) "I could easily incorporate my MH-Online therapy sessions into my daily routine. My therapist was very responsive and supportive of me." (Jens R., 25) Participants in IG 2 received three testimonials targeted to employees (i.e. GET.ON interventions) presented by employee personas that varied in age, gender, occupation and type of mental health training (Textbox S4).

Supplementary Textbox S4. Testimonials for "GET.ON" (IG2).
"More and more, the stress I was experiencing at work was spilling over into my private life. Upon learning recurrent rules about coping with stress, I began to get used to applying them, and it became easier to deal with stress without building up additional stress in doing so." (Klaus M., 51, call center employee, stress management training) "Prior to the training program, I was just running in circles trying to deal with my problems at work. I can only recommend this type of training to anyone who wants to work on themselves and needs to learn the right tools to do so. It helped me become much stronger in only a matter of weeks. Thank you for this! Sandra F., 46, staff member, problem-solving training) "It really helps me to write down some of my thoughts and receive your comments on them. Your answers give me the courage to work on myself and my problems and to get a handle on these problems. And they also give me some new perspectives by mentioning certain aspects or reflecting on situations in a different light. This in turn helps me reflect differently upon things." (Janine T., teacher, 52, prevention training for exhaustive depression) Participants in IG 3 read three testimonials targeted to students (StudiCare trainings, see Textbox S5). Due to the employment of the virtual lab of the University of Hagen, we focused on experiences presented by distance-learning students that were also applicable to traditional students.

Supplementary Textbox S5. Testimonials for "StudiCare" (IG3).
"It is wonderful for me as a student of a distance-learning university to receive support for dealing with mental problems. I struggle specifically with test anxiety. The StudiCare training program and the respective feedback from my coach helped a lot with this. Just knowing that there is someone out there whom I can contact anonymously for help is such a relief. (Anna S., B.A. Communications, 29, test anxiety training) "At first I was a bit surprised about the whole process, but very quickly I began to see similar advantages in this type of training as in my distance-learning studies. This is a wonderful first step into therapy and training. It helped me face the stress and the corresponding problems caused by the doubled strain of working and studying simultaneously. For me this was the first step towards getting help via face-to-face therapy. Without this "easy" kick-off, I would never have gone." (Tim K., Philosophy major, 40, prevention training for exhaustive depression) "I was able to participate where and when it was good for me. It was this kind of flexibility that allowed me to commit to such a training while juggling my distance-learning studies, family life and job simultaneously -and it worked! Highly recommended!" (Claudia W, Psychology major, 37, stress management training) Supplementary Textbox S6 shows the testimonial texts for the three IGs in direct comparison. Self-constructed based on real testimonials for employees. Information: name, age, profession, and type of training.
"More and more, the stress I was experiencing at work was spilling over into my private life. Upon learning recurrent rules about coping with stress, I began to get used to applying them, and it became easier to deal with stress without building up additional stress in doing so." (Klaus M., 51, call center employee, stress management training) "It really helps me to write down some of my thoughts and receive your comments on them. Your answers give me the courage to work on myself and my problems and to get a handle on these problems. And they also give me some new perspectives by mentioning certain aspects or reflecting on situations in a different light. This in turn helps me reflect differently upon things." (Janine T., teacher, 52, prevention training for exhaustive depression) "Prior to the training program, I was just running in circles trying to deal with my problems at work. I can only recommend this type of training to anyone who wants to work on themselves and needs to learn the right tools to do so. It helped me become much stronger in only a matter of weeks. Thank you for this! Sandra F., 46, staff member, problem-solving training) Testimonials for "StudiCare" (IG3).
Self-constructed based on real testimonials for students. Information: name, age, study subject, and type of training.
"I was able to participate where and when it was good for me. It was this kind of flexibility that allowed me to commit to such a training while juggling my distance-learning studies, family life and job simultaneously -and it worked! Highly recommended!" (Claudia W, Psychology major, 37, stress management training) "At first I was a bit surprised about the whole process, but very quickly I began to see similar advantages in this type of training as in my distance-learning studies. This is a wonderful first step into therapy and training. It helped me face the stress and the corresponding problems caused by the doubled strain of working and studying simultaneously. For me this was the first step towards getting help via face-to-face therapy. Without this "easy" kick-off, I would never have gone." (Tim K., Philosophy major, 40, prevention training for exhaustive depression) "It is wonderful for me as a student of a distance-learning university to receive support for dealing with mental problems. I struggle specifically with test anxiety. The StudiCare training program and the respective feedback from my coach helped a lot with this. Just knowing that there is someone out there whom I can contact anonymously for help is such a relief. (Anna S., B.A. Communications, 29, test anxiety training)

Full overview of information texts with or without testimonials
For the sake of completeness, a differentiated full overview of the text-based information with or without testimonials per group is shown. This includes information that may be redundant in terms of identical contents that were already fully or partly described in the prior section.

Information intervention for the active control group (information only)
The following text will provide you with information on guided electronic mental health trainings and therapies to help cope with psychological problems such as stress and to build resilience. Please read the description carefully and answer the questions regarding your opinion on these novel interventions afterwards. There will be no questions to test your knowledge of these interventions.
Electronic mental health trainings and therapies with regards to mental health offer new opportunities to improve and/or expand care for afflicted persons. Mental illness often remains untreated. Internet-based psychotherapy can be considered a means to bridge the gap and offer care to more individuals. Numerous scientific studies have shown the efficacy of internetbased therapy for a broad range of psychological problems that can, for instance, arise from prolonged exposure to stress.
These internet-based interventions employ methods from Cognitive Behavioral Therapy that are also used in regular face-to-face therapy sessions. For instance, there are trainings to generally help cope with stress, to build resilience, to cope with mild or moderate depression, anxiety disorders or eating disorders. One of the currently existing forms are internet-based guided programs that allow patient to access online programs or online self-learning resources with the help of a therapist. Daily use of an app can also be employed. Patients communicate with their therapist via e-mail, chat or video conference. Flexibility regarding time and location is seen as a big advantage.

Information and untargeted testimonials in IG1 (hypothetical MH-Online)
The following text will provide you with information on guided electronic mental health trainings and therapies to help cope with psychological problems such as stress and to build resilience. Please read the description carefully and answer the questions regarding your opinion on these novel interventions afterwards. There will be no questions to test your knowledge of these interventions.
Electronic mental health trainings and therapies with regards to mental health offer new opportunities to improve and/or expand care for afflicted persons. Mental illness often remains untreated. Internet-based psychotherapy can be considered a means to bridge the gap and offer care to more individuals. Numerous scientific studies have shown the efficacy of internetbased therapy for a broad range of psychological problems that can, for instance, arise from prolonged exposure to stress.
These internet-based interventions employ methods from Cognitive Behavioral Therapy that are also used in regular face-to-face therapy sessions. For instance, there are trainings to generally help cope with stress, to build resilience, to cope with mild or moderate depression, anxiety disorders or eating disorders. One of the currently existing forms are internet-based guided programs that allow patient to access online programs or online self-learning resources with the help of a therapist. Daily use of an app can also be employed. Patients communicate with their therapist via e-mail, chat or video conference. Flexibility regarding time and location is seen as a big advantage.
These online trainings consist of 6 consecutive one-hour sessions. You can accompany the online sessions with an app that allows for daily use. Additionally, you may receive personal coaching sessions. The training program aims to help you regain productivity. The resilience training program includes sessions on self-efficacy, optimism, relationships, and self-care. During the stress management training programs, participants learn to identify personal issues, practice coping mechanisms, apply problem-solving techniques, and learn how to manage difficult emotions.

Information and testimonials targeted to employees in IG2 (GET.ON)
The following text will provide you with information on guided electronic mental health trainings and therapies to help cope with psychological problems such as stress and to build resilience. Please read the description carefully and answer the questions regarding your opinion on these novel interventions afterwards. There will be no questions to test your knowledge of these interventions.
Electronic mental health trainings and therapies with regards to mental health offer new opportunities to improve and/or expand care for afflicted persons. Mental illness often remains untreated. Internet-based psychotherapy can be considered a means to bridge the gap and offer care to more individuals. Numerous scientific studies have shown the efficacy of internetbased therapy for a broad range of psychological problems that can, for instance, arise from prolonged exposure to stress.
These internet-based interventions employ methods from Cognitive Behavioral Therapy that are also used in regular face-to-face therapy sessions. For instance, there are trainings to generally help cope with stress, to build resilience, to cope with mild or moderate depression, anxiety disorders or eating disorders. One of the currently existing forms are internet-based guided programs that allow patient to access online programs or online self-learning resources with the help of a therapist. Daily use of an app can also be employed. Patients communicate with their therapist via e-mail, chat or video conference. Flexibility regarding time and location is seen as a big advantage.
These online trainings consist of 6 consecutive one-hour sessions. You can accompany the online sessions with an app that allows for daily use. Additionally, you may receive personal coaching sessions. The training program aims to help you regain productivity. The resilience training program includes sessions on self-efficacy, optimism, relationships, and self-care. During the stress management training programs, participants learn to identify personal issues, practice coping mechanisms, apply problem-solving techniques, and learn how to manage difficult emotions.
"More and more, the stress I was experiencing at work was spilling over into my private life. Upon learning recurrent rules about coping with stress, I began to get used to applying them, and it became easier to deal with stress without building up additional stress in doing so." (Klaus M., 51, call center employee, stress management training) "Prior to the training program, I was just running in circles trying to deal with my problems at work. I can only recommend this type of training to anyone who wants to work on themselves and needs to learn the right tools to do so. It helped me become much stronger in only a matter of weeks. Thank you for this! Sandra F., 46, staff member, problem-solving training) "It really helps me to write down some of my thoughts and receive your comments on them. Your answers give me the courage to work on myself and my problems and to get a handle on these problems. And they also give me some new perspectives by mentioning certain aspects or reflecting on situations in a different light. This in turn helps me reflect differently upon things." (Janine T., teacher, 52, prevention training for exhaustive depression)

Information and testimonials targeted to students in IG3 (StudiCare)
The following text will provide you with information on guided electronic mental health trainings and therapies to help cope with psychological problems such as stress and to build resilience. Please read the description carefully and answer the questions regarding your opinion on these novel interventions afterwards. There will be no questions to test your knowledge of these interventions.
Electronic mental health trainings and therapies with regards to mental health offer new opportunities to improve and/or expand care for afflicted persons. Mental illness often remains untreated. Internet-based psychotherapy can be considered a means to bridge the gap and offer care to more individuals. Numerous scientific studies have shown the efficacy of internetbased therapy for a broad range of psychological problems that can, for instance, arise from prolonged exposure to stress.
These internet-based interventions employ methods from Cognitive Behavioral Therapy that are also used in regular face-to-face therapy sessions. For instance, there are trainings to generally help cope with stress, to build resilience, to cope with mild or moderate depression, anxiety disorders or eating disorders. One of the currently existing forms are internet-based guided programs that allow patient to access online programs or online self-learning resources with the help of a therapist. Daily use of an app can also be employed. Patients communicate with their therapist via e-mail, chat or video conference. Flexibility regarding time and location is seen as a big advantage.
These online trainings consist of 6 consecutive one-hour sessions. You can accompany the online sessions with an app that allows for daily use. Additionally, you may receive personal coaching sessions. The training program aims to help you regain productivity. The resilience training program includes sessions on self-efficacy, optimism, relationships, and self-care. During the stress management training programs, participants learn to identify personal issues, practice coping mechanisms, apply problem-solving techniques, and learn how to manage difficult emotions.
"It is wonderful for me as a student of a distance-learning university to receive support for dealing with mental problems. I struggle specifically with test anxiety. The StudiCare training program and the respective feedback from my coach helped a lot with this. Just knowing that there is someone out there whom I can contact anonymously for help is such a relief. (Anna S., B.A. Communications, 29, test anxiety training) "At first I was a bit surprised about the whole process, but very quickly I began to see similar advantages in this type of training as in my distance-learning studies. This is a wonderful first step into therapy and training. It helped me face the stress and the corresponding problems caused by the doubled strain of working and studying simultaneously. For me this was the first step towards getting help via face-to-face therapy. Without this "easy" kick-off, I would never have gone." (Tim K., Philosophy major, 40, prevention training for exhaustive depression) "I was able to participate where and when it was good for me. It was this kind of flexibility that allowed me to commit to such a training while juggling my distance-learning studies, family life and job simultaneously -and it worked! Highly recommended!" (Claudia W, Psychology major, 37, stress management training)