Table 1.

Means, SDs, and intercorrelations among study variables.

Variable	Mean	SD	1	2	3	4
Within
1. Instant Message Demand	3.00	0.89	1	0.167 **	0.233 **	−0.134 **
2. Cognitive engagement	3.73	0.60	0.504 **	1	0.654 **	−0.489 **
3. Emotional engagement	3.54	0.61	0.550 **	0.895 **	1	−0.486 **
4. Psychological withdrawal	1.96	0.65	0.121	−0.057	−0.098	1
Between
5. Self-control	3.43	0.40	0.102	0.234	0.334 **	−0.326 **

Note. N at Level 1 = 632, N at Level 2 = 66. SD = standard deviation. Variables 1–4 are within-individual (Level 1) variables. Their means and SDs are based on between-person scores. Intercorrelations above the diagonal are based on within-individual scores; intercorrelations below the diagonal are based on between-individual scores. Self-control is a between-individual variable. The intercorrelations of self-control with variables 1–4 are based on between-individual scores (i.e., we aggregated variables 1–4 at the individual-level). ** p < 0.01.