Table 1.
Mean (SD) Hours of Screen Use at Each Time Point, by Cohort
| Screen Use Measure | Time 11 | Time 22 | Time 33 | Time 44 | Time 55 | Time 66 |
|---|---|---|---|---|---|---|
| Overall | ||||||
| Grade 5 | 3.05 (2.32) | 2.65 (2.16) | 2.60 (2.13) | 2.60 (2.12) | 2.89 (2.22) | 3.02 (2.20) |
| Grade 7 | 3.92 (2.44) | 3.78 (2.61) | 3.67 (2.28) | 3.89 (2.47) | 3.92 (2.38) | 4.04 (2.43) |
| Grade 9 | 4.95 (2.70) | 4.53 (2.47) | 4.57 (2.44) | 4.66 (2.63) | 4.63 (2.60) | 4.48 (2.47) |
| Social Networking | ||||||
| Grade 5 | 0.88 (1.77) | 0.86 (1.84) | 0.76 (1.40) | 0.93 (1.75) | 1.18 (2.00) | 1.30 (1.99) |
| Grade 7 | 1.70 (2.45) | 1.71 (2.51) | 1.58 (2.17) | 1.72 (2.41) | 1.82 (2.33) | 1.93 (2.32) |
| Grade 9 | 2.52 (2.99) | 2.17 (2.58) | 2.20 (2.56) | 2.28 (2.71) | 2.48 (2.69) | 2.19 (2.50) |
| Gaming | ||||||
| Grade 5 | 2.09 (2.28) | 1.86 (2.26) | 1.64 (2.06) | 1.60 (1.94) | 1.41 (2.02) | 1.38 (1.97) |
| Grade 7 | 1.88 (2.16) | 1.71 (2.43) | 1.27 (1.85) | 1.43 (2.10) | 1.29 (2.24) | 1.23 (2.10) |
| Grade 9 | 1.62 (2.33) | 1.57 (2.37) | 1.40 (2.22) | 1.42 (2.43) | 1.31 (2.57) | 1.17 (2.29) |
| Web | ||||||
| Grade 5 | 1.46 (1.93) | 1.35 (1.81) | 1.26 (1.65) | 1.25 (1.64) | 1.46 (1.64) | 1.34 (1.47) |
| Grade 7 | 1.73 (1.99) | 1.90 (2.15) | 1.64 (1.64) | 1.84 (2.10) | 1.78 (1.94) | 1.79 (1.95) |
| Grade 9 | 2.09 (2.17) | 2.04 (2.14) | 1.87 (2.25) | 2.17 (2.20) | 2.42 (2.50) | 2.15 (2.42) |
| Passive | ||||||
| Grade 5 | 2.45 (2.28) | 2.18 (2.17) | 2.09 (1.96) | 2.14 (2.11) | 2.06 (1.99) | 2.04 (1.89) |
| Grade 7 | 2.73 (2.41) | 2.80 (2.52) | 2.35 (2.01) | 2.47 (2.33) | 2.41 (2.27) | 2.48 (2.28) |
| Grade 9 | 3.02 (2.59) | 2.84 (2.32) | 2.69 (2.43) | 2.73 (2.53) | 2.59 (2.57) | 2.56 (2.65) |
1N = 590 to 652. 2N = 481 to 589. 3N = 461 to 539. 4N = 476 to 541. 5N = 373 to 483. 6N = 378 to 462