Table 1 Overview of the included item-specific social-cognitive variables
|  | Item questionnaire | Baseline (mean ± SD) | Follow-up (mean ± SD) | Change-score follow-up - baseline (mean ± SD) |
|---|---|---|---|---|
TV viewing | ||||
 Attitude 1(a) | I think watching TV is pleasant | 4.08 ± 0.88 | 4.03 ± 0.86 | −0.08 ± 0.74 |
 Attitude 2(a) | Watching TV takes time away from doing other important things | 2.69 ± 1.24 | 2.60 ± 1.16 | 0.04 ± 1.25 |
 Attitude 3(a) | I enjoy watching TV for many hours at a time | 2.68 ± 1.21 | 2.69 ± 1.20 | 0.02 ± 1.14 |
 Attitude 4(a) | Watching TV is my way to relax after a school day/workday | 3.48 ± 1.21 | 3.33 ± 1.29 | −0.18 ± 1.03 |
 Self-efficacy 1(a) | I consider it possible to reduce my TV time(d) | / | / | / |
 Self-efficacy 2(a) | I consider it possible to turn off the TV during weekend days until 5:00 p.m. | 4.20 ± 1.19 | 4.23 ± 1.13 | −0.03 ± 1.31 |
 Self-efficacy 3(a) | I consider it possible to turn off the TV during meals | 4.37 ± 1.07 | 4.46 ± 0.96 | 0.03 ± 1.11 |
 Norm(a) | I think that I spend too much time watching TV | 2.20 ± 1.16 | 2.16 ± 1.13 | 0.05 ± 1.06 |
 Social norm(a) | My family members think I spend too much time watching TV | 1.76 ± 0.97 | 1.75 ± 0.84 | −0.03 ± 0.82 |
 Social support 1(a) | My family members encourage me to watch less TV | 1.84 ± 0.97 | 1.81 ± 0.88 | 0.04 ± 0.91 |
 Social support 2(a) | My friends encourage me to watch less TV(f) | / | / | / |
 Modelling 1(b) | How long, on average, does your partner spend watching TV? | 5.52 ± 2.27 | 5.28 ± 2.32 | −0.03 ± 1.27 |
PC-use | ||||
 Attitude 1(a) | I think using a computer is pleasant in leisure time | 3.68 ± 1.09 | 3.63 ± 1.17 | −0.03 ± 1.05 |
 Attitude 2(a) | Using a computer takes time away from doing other important things | 2.54 ± 1.25 | 2.51 ± 1.23 | 0.04 ± 1.30 |
 Attitude 3(a) | I enjoy using a computer for many hours at a time | 2.45 ± 1.16 | 2.45 ± 1.21 | 0.02 ± 1.17 |
 Attitude 4(a) | Using a computer is my way to relax after a school day/workday | 2.47 ± 1.25 | 2.45 ± 1.26 | 0.01 ± 1.17 |
 Self-efficacy 1(a) | I consider it possible that I do not use a computer for some days in the week (leisure time) | 3.48 ± 1.38 | 3.43 ± 1.38 | −0.07 ± 1.52 |
 Self-efficacy 2(a) | I consider it possible to reduce my computer time in leisure time | 3.16 ± 1.21 | 3.18 ± 1.16 | −0.03 ± 1.35 |
 Norm(a) | I think that I spend too much time using a computer | 1.99 ± 1.13 | 2.03 ± 1.11 | 0.02 ± 1.01 |
 Social norm (a) | My family members think I spend too much time using a computer(d) | / | / | / |
 Social support 1(a) | My family members encourage me to spend less time using a computer in leisure time(d) | / | / | / |
 Social support 2(a) | My friends encourage me to spend less time using a computer in leisure time | 1.80 ± 0.95 | 1.83 ± 0.91 | 0.06 ± 0.92 |
 Modelling 1(b) | How long, on average, does your partner sit when using the computer (tablet, internet on smartphone, laptop, desktop,…) in leisure time?(d) | / | / | / |
Motorized transport | ||||
 Attitude 1(a) | I feel lazy arriving at my destination after motorized transport(e) | 3.80 ± 1.14 | 3.70 ± 1.12 | −0.11 ± 1.29 |
 Attitude 2(a) | I think using motorized transport is pleasant | 3.50 ± 1.09 | 3.24 ± 1.16 | −0.14 ± 1.08 |
 Attitude 3(a) | I think it is pleasant to work or to rest as a passenger during motorized transport | 3.01 ± 1.23 | 2.93 ± 1.22 | 0.03 ± 1.44 |
 Self-efficacy 1(a) | I consider it possible to get off the bus/metro spontaneously 1 stop before my destination and to walk the remaining distance | 3.01 ± 1.34 | 3.25 ± 1.25 | 0.22 ± 1.30 |
 Self-efficacy 2(a) | I consider it possible to park the car somewhat further spontaneously and to walk the remaining distance | 3.27 ± 1.31 | 3.49 ± 1.20 | 0.16 ± 1.14 |
 Self-efficacy 3(a) | I consider it possible to take the bicycle or to go by foot spontaneously even if it is possible to use a car | 4.02 ± 1.14 | 4.16 ± 1.03 | 0.14 ± 1.11 |
 Norm(a) | I think that I spend too much time using motorized transport | 2.39 ± 1.23 | 2.42 ± 1.17 | 0.06 ± 1.12 |
 Social norm(a) | My family members think I spend too much time using motorized transport | 1.95 ± 1.06 | 1.95 ± 0.96 | 0.07 ± 0.81 |
 Social support 1(a) | My family members encourage me to use (more often) active transport (to bicycle or to walk) | 2.85 ± 1.31 | 2.71 ± 1.28 | −0.16 ± 1.27 |
 Social support 2(a) | My friends encourage me to use (more often) active transport (to bicycle or to walk)(f) | / | / | / |
 Modelling 1(c) | The most chosen transportation possibility to go to work/school from my partner | 2.05 ± 0.65 | 2.04 ± 0.68 | −0.03 ± 0.49 |
 Modelling 2(c) | The most chosen transportation possibility in leisure time from my partner | 2.11 ± 0.63 | 2.19 ± 0.70 | 0.09 ± 0.60 |
Occupation | ||||
 Attitude 1(a) | My attention decreases while sitting for a long time | 3.11 ± 1.32 | 3.23 ± 1.22 | 0.22 ± 1.77 |
 Attitude 2(a) | I think it is pleasant to sit for a long time during working hours | 2.27 ± 1.02 | 2.26 ± 1.01 | 0.03 ± 1.55 |
 Attitude 3(a) | Sitting at work is an ideal opportunity to rest | 2.48 ± 1.22 | 2.34 ± 1.25 | −0.14 ± 1.68 |
 Self-efficacy 1(a) | I consider it possible to do certain tasks (calling,…) while standing | 3.64 ± 1.23 | 3.71 ± 1.14 | 0.18 ± 1.75 |
 Self-efficacy 2(a) | I consider it possible to stand up for a while after a period of uninterrupted sitting | 4.38 ± 0.85 | 4.23 ± 0.92 | −0.15 ± 1.32 |
 Self-efficacy 3(a) | I consider it possible to stand up more often during breaks | 3.43 ± 1.39 | 3.58 ± 1.39 | 0.26 ± 2.12 |
 Norm(a) | I think that I spend too much time sitting at work | 2.54 ± 1.35 | 2.64 ± 1.37 | 0.10 ± 2.03 |
 Social norm(a) | My colleagues think I spend too much time sitting | 1.83 ± 0.89 | 1.88 ± 0.98 | 0.08 ± 1.33 |
 Social support 1(a) | My colleagues encourage me to sit less(d) | / | / | / |