Preston's Curvilinear Control-Linear Feedback Model: A Replication Study Using a Sample of County-Based Public Assistance Case Managers Across the State of New York

Background and Purpose:  Work motivation has received little empirical attention in the social work literature.  Organizational theory asserts that sustaining motivation in challenging occupational environments, such as human service organizations, requires sufficient job control.  When workload demands are perceived as high, job control allows employees to engage in new learning, skill development, and the adjustment work methods/processes.  Reduced work-anxiety, resulting from these behavioral actions, increases job competence which in turn elevates motivation.  Inconsistent empirical support for this idea has led some scholars to suggest that job control’s influence on motivation in demanding workplace environments may be curvilinear or influenced by an additional variable.  Other scholars argue that distinct occupational-level attributes associated with human service organizations may explain conflicting findings.

Drawing from the job demands-control model, challenge-hindrance framework, and environmental uncertainty literature, a recent survey study revealed that the control-motivation association in a sample of child welfare case managers was curvilinear and contingent on goal-related feedback from the wider occupational milieu.  Relative to colleagues who reported moderate levels of job control, child welfare case managers who reported higher or lower levels of job control experienced greater motivation when instrumental feedback was high, rather than low.  Accordingly, the current study seeks to replicate and extend this unique and original empirical finding.

              1) a nonsignificant main effect for curvilinear job control on motivation is predicted;

              2) a significant curvilinear control-linear feedback interaction on motivation is

                   predicted.

Methods:  Six hundred and fifty-seven county-based public assistance case managers across 12 New York State counties were surveyed (70 % response rate).  Reliabilities and factor loadings for all study variables achieved recommended levels.  Discriminant validity was established using maximum likelihood estimation with varimax rotation.  Procedures outlined by Aiken and West were used to test the curvilinear control-linear feedback interaction.  Except for three multivariate outliners, no violations of OLS regression were noted.

 Results:  Both hypotheses were supported.  Null findings were observed for job control’s (β = 0.01, n.s.) curvilinear relationship with motivation.  Further, a significant curvilinear control-linear feedback interaction (β = 0.12, p< 0.05) on motivation was uncovered.  The squared job control and linear instrumental feedback variables explained 15% of the variance in the criterion measure.  Finally, the effect size of the two-way interaction term was 4 times larger than the median effect size reported in a 30-year review of categorical moderators.

Conclusion and Implications:  Study data support the two proposed hypotheses.  As such, research findings are the first known empirical work to replicate Preston’s curvilinear control-linear feedback model.  Empirical evidence suggests that social work organizations seeking to strengthen case manager motivation via job control must consider the construct’s dynamic and interdependent relation with instrumental feedback.  Failing to do so may result in greater job control attenuating rather than elevating motivation.  Feedback source is one area of future research.  Given that client encounters are a critical source of feedback information on a case manager’s level of competence, receiving instrumental feedback from her/his direct supervisor is less likely to influence job control’s curvilinear association with motivation.