Dual Process Theory
Dual Process .Theory says that we have two ways of
making decisions about things:

very fast, without reasoning, termed intuitive
decision making (also known as being in
System 1, or Type 1 processing), OR
Intuition
RECOGNIZED

by deliberate and purposeful thinking termed
analytical reasoning (also known as being in
System 2, or Type 2 processing).
The model was first described by the psychologists
Schneider and Shiffrin in 1977, but not translated
into the medical literature until quite recently. It is
Patient
Presentation
Pattern
Processor
Pattern
Recognition
Executive
override
T
Dysrationalia
override
Calibration
Diagnosis
Repetition
NOT
RECOGNIZED
Analytical
schematically illustrated in the figure to the right.
Main Operating Characteristics of the Model
1. Most of our conscious time is in System 1 – psychologists estimate 95% of our time is spent there. We can move from one
pattern to another in what are called ‘serial associations’ i.e. the brain has an automatic response to each pattern that it
encounters, one after the other. This generally works well and is how we get through most of our day.
2. Most heuristics (short cuts, rules of thumb, maxims) and biases (estimated to be > 100) are in System 1 – some biases
do occur in System 2 but the majority is in System 1.
3. Most errors occur in System 1 – mainly because heuristics work most of the time but not all of the time. However, errors
do occur in System 2 typically when basic science is being ignored, wrong assumptions are being made or facts are
incorrect.
4. Repetitive operations of System 2 get us into System 1. When we first encounter a new problem, it has to be dealt with by
System 2. Repeated work in System 2 allows the development of habit and expertise so that the problem can automatically
be dealt with by System 1 without requiring much of our attention. This is how skills and habits are acquired and saves us a
lot of needless cognitive effort,
5. System 2 override of System 1 – basically this is how System 2 keeps an eye on what System 1 is doing. It is variously
referred to as metacognition or mindfulness and is the basis for cognitive debiasing strategies.
6. System 1 override of System 2 – typically this is irrational behavior e.g. road rage, ignoring clinical decision rules
7. Toggle function – allows us to dynamically move between System 1 and System 2. Some clinicians say that they get all
their ideas in System 1 but make all their final decisions in System 2.
8. Cognitive Miser function – the brain naturally defaults to System 1 where it uses less energy – and we can be ‘comfortably
numb’, especially when we are in ‘wicked’ work environments, very busy (cognitively overloaded), fatigued, sleep
deprived, or experiencing negative mood. To go into System 2, in contrast, generates work for the brain and tends to be
resisted. Preservation of the status quo and resisting change allows us to avoid work.