Disentangling Efficacy and Expectations: A Prospective, Cross-lagged Panel Study of Cancer Survivors' Physical Activity.

Background: Despite demonstrated utility of Bandura's social cognitive theory for increasing physical activity among cancer survivors, the validity of the originally hypothesized relationships among self-efficacy, outcome expectations, and physical activity behavior continues to be debated.

Purpose: To explore the temporal ordering of outcome expectations and self-efficacy as they relate to moderate-to-vigorous physical activity behavior.

Methods: Longitudinal data from cancer survivors (N = 1,009) recently completing treatment were used to fit six cross-lagged panel models, including one parent model, one model representing originally hypothesized variable relationships, and four alternative models. All models contained covariates and used full information maximum likelihood and weighted least squares mean and variance adjusted estimation. Tests of equal fit between the parent model and alternative models were conducted.

Results: The model depicting Bandura's originally hypothesized relationships showed no statistically significant relationship between outcome expectations and physical activity (p = .18), and was a worse fit to the data, compared with the parent model [Χ2 (1) = 5.92, p = .01]. An alternative model showed evidence of a reciprocal relationship between self-efficacy and outcome expectations, and was statistically equivalent to the parent model [Χ2(1) = 2.01, p = .16].

Conclusions: This study provides evidence against Bandura's theoretical assertions that (a) self-efficacy causes outcome expectations and not vice versa, and (b) outcome expectation has a direct effect on physical activity. Replication within population subgroups and for other health behaviors will determine whether the social cognitive theory needs modification. Future trials should test whether differential construct ordering results in clinically meaningful differences in physical activity behavior change.