Stress can have an affect on SA, sometimes positive, but more usually negative.
Stress can be physical (noise, vibration, heat, cold, fatigue, etc.) or social/ psychological (fear, anxiety, uncertainty, mental load, time pressure, perceived time pressure, consequences of events, etc.). High workload is a form of stress, either long term high workload (e.g. a short-haul flight through several sectors in busy airspace, with an inexperienced crew), or short term or even momentary high workload or overload (e.g. bad weather on approach).
Depending on the individual, some degree of stress may improve performance in general, including SA. More often, however, stress results in reduced SA since it competes with SA for an individual’s limited attention capacity, and may result in attentional narrowing.
Other consequences may include reduced working memory capacity, and reduced information intake. Aural inputs may be significantly reduced, with peripheral visual inputs suffering next. This is a strong argument for placing master warning lights in the central visual area in cockpits, rather than rely upon peripheral attention-getters or aural warnings.
Stress can also result in decisions being made without all the pertinent information having been considered (e.g. shutting down wrong engine without looking to see which one is on fire!), and also with failing to take account of contradictory information once a decision has been made, attention being given only to information which supports the decision. Training can make people aware that this is a danger, help them to recognise the symptoms of stress and reduced SA, and train them to actively search for, and attend to, all pertinent sources of information before making a decision or acting upon a decision.
Recognition of reduced SA is almost as important as subsequent retrieval of good SA.
Line oriented Flight Training (LOFT) exercises and debriefs are a useful way to improve on recognising when SA is reduced, with regard to both individuals and the flight deck crew team.