The Job Demand-Control-Support Model: A Practitioner's Guide
High job demands don't harm workers by themselves. What makes work damaging or sustaining, is the interaction of demands, control, and support.
Active
High demands offset by high control. Stretching but not harmful; associated with learning and growth.
Typical Indicators
- Stretch
- Fatigue balanced by recovery
- Skill development
Implicated SWA Hazards
The Core Framework
Karasek's 1979 Demand-Control model is the foundation of modern occupational health psychology. It proposes that psychological strain doesn't emerge from demands alone, but from the interaction between psychological demands and decision latitude (control).
In 1988, Johnson & Hall extended the model to include social support, creating the Job Demand-Control-Support (JDCS) model. This addition surface the iso-strain configuration — short for "isolated strain" — which has since become the benchmark for identifying the highest-risk work environments.
Evidence Base
Longitudinal research — including the Whitehall II study and the IPD-Work Consortium meta-analysis across 200,000 European workers — has linked iso-strain configurations to elevated risk of coronary heart disease, clinical depression, anxiety, and musculoskeletal disorders.
Mapping to SWA Common Hazards
How high-level psychological dimensions map to the common psychosocial hazards identified by Safe Work Australia.
| JDCS Dimension | Corresponding SWA Hazards |
|---|---|
| Job demands | |
| Job control | |
| Social support | |
| Context amplifiers |
Operationalising with COPSOQ III
PsychProof administers the COPSOQ III instrument natively. Here is how the JDCS model dimensions translate directly to measurable survey scales.
Why Iso-strain Co-occurrence Matters
A workgroup flagging high demands alone is elevated risk. A workgroup flagging high demands, low control, and low support simultaneously is in the iso-strain configuration — the pattern with the strongest evidence base for adverse health outcomes in the occupational health literature.
Workgroup A
Workgroup B
Workgroup C
PsychProof's organisational topology layer identifies these patterns of co-occurrence. Registers often miss compounded risk because they track hazards individually; we track the worker experience within the organisational structure.
The iso-strain configuration has the strongest evidence base for adverse outcomes — particularly cardiovascular disease, clinical depression, and musculoskeletal disorders (Johnson & Hall, 1988; Kivimäki et al., 2012).
What this means for WHS Duty Holders
The WHS Act s.19 primary duty of care requires duty holders to eliminate or minimise psychosocial risks so far as is reasonably practicable.
Where JDCS or iso-strain conditions are present, failing to implement controls becomes foreseeable. Decisions in leading civil cases like Kozarov v State of Victoria and Elisha v Vision Australia reinforce that ignorance of these dynamic risk configurations is not a defence.
Use the 'Should I Act' decision toolLegislative Anchors
Evidence Timeline
Track the longitudinal research that transformed JDCS from a theory into the global standard for mental health at work.