A commonly used human error classification
scheme is the “skill-rule-knowledge” (SRK)
model. This model refers to the cognitive mode
in which the individual is operating when he or
she commits an error. Actions that are largely
performed automatically, requiring little
conscious attention, are considered skill-based
actions, such as tying one’s shoes or driving on
the open freeway. Actions that require an
intermediate level of attention are considered
rules-based actions, such as deciding which
clothes to wear or when to proceed at a four-
way stop. Actions that require a high level of
concentration, usually in the setting of
situations that are new to the individual, are
knowledge-based actions, such as playing a
sport for the first time or driving in poor
visibility conditions in an unfamiliar city.