Two factors influence how someone responds to subjective wellbeing surveys. First, the influence from environmental factors. The second is our genetically set level of mood (the subjective wellbeing set-point). This mood component is a stable, mildly positive background influence, which is normally distributed within Australia's general population between 75 and 90 percentage points, on a 0–100 percentage-point scale where 0 = no positive feelings at all and 100 = very high positive feelings (Capic et al., 2018).

Therefore, our answer to a question such as “Thinking about your own life, how satisfied do you feel?” contains influences from both the genetically set level of mood and our current emotional state. Under normal operating conditions, with low levels of emotional input from the environment, the question about satisfaction with life taps a person's set level of mood. However, suppose you ask the question immediately after winning Tattslotto or a car accident — in that case, the scores will contain both the influence from mood and a greater contribution from either positive or negative emotions.

Sensitivity to fluctuating environmental situations is by design. In evolutionary terms, hominins are selected for survival when threats eliciting strong emotions produce focused attention and the subsequent engagement of external and internal buffers to reduce the threat level (Frijda, 1986). External responses include behaviours such as removing oneself from an immediate threat, or using money to access treatment for the source of strong negative emotions such as illness or disability. Internal buffers such as self-esteem, optimism and perceived control can minimise the impact of a personal failure on our positive view of self. At YD, we measure these protective mechanisms — referred to as external and internal buffers.

Homeostatic Defeat

While someone's subjective wellbeing is held stable under normal conditions, the protective system can be challenged by adverse life circumstances. Under these conditions, the challenging agent begins to lower someone's subjective wellbeing. When this happens, the system's external defensive mechanisms (buffers) are activated. If the external buffers fail, internal buffers are employed. Occasionally, both external and internal buffers are overwhelmed and someone's subjective wellbeing falls below its homeostatic range. This condition is termed homeostatic defeat and correlates with mental health concerns such as depressive symptoms (Cummins, 2010).

Resilience

Resilience refers to the level of systemic threat the homeostatic system is able to withstand before subjective wellbeing drops below its homeostatic range — and how quickly subjective wellbeing is returned to its normal range of values.