Dual Process and Cognitive
Bias in Clinical Decision Making
Joan M. Von Feldt, MD, MSEd
Professor of Medicine
vonfeldt@mail.med.upenn.edu
Thinking Fast and Slow
Daniel Kahneman
Approaches to Decision Making
Modular
responsivity
Deliberation
without attention
Thin
Slicing
Inductive
reasoning
Recognition
Primed
Heuristics and Biases
Intuitive
Hypothetico-deductive
reasoning
Gestalt
effect
Robust
Decision
Making
Exhaustion
Strategy
Bounded
rationality
Normative
reasoning
Bayesian
reasoning
Analytical
Croskerry. Adv in Health Sci Ed 2009; 14:27-35
Properties of the 2 types of decision-making
Cognitive Style
Cognitive Awareness
Automaticity
Rate
Effort
Emotional Component
Scientific Rigor
Errors
System I
(Intuitive)
Heuristic
Low
High
Fast
Low
High
System II
(Analytical)
Systematic
High
Low
Slow
High
Low
Low
More
High
Less
Examples: System 1 & 2 Thinking

Your route to work

An out of town guest staying with you who
will meet you at your work

Your route to work after being away for 20
years or major road work
Model for diagnostic reasoning based on
pattern recognition and dual-process theory
Croskerry P. Clinical cognition and diagnostic error: applications of a dual process model
of reasoning. Adv Health Sci Educ Theory Pract. 2009 Sep;14 Suppl 1:27-35.
Heuristics





Pattern Recognition
Illness Scripts
Gestalt
Instance Scripts
i.e “Blink”; “Thinking Fast”
Heuristics
Can be good:
» provide cognitive “short cuts” in the face of complex
situations
» Help us to be efficient
Can be bad:
» They tend to be thinking traps – so beware!
» Can adversely influence our diagnostic decisions
Croskerry, P. Acad Med 2003; 78:775-80.
Institute of Medicine Report

Published in 1999

Addressed the problem of
preventable medical errors

Charged the healthcare
industry to evaluate and
change their systems to
prevent patient harm
Systems Errors: Complicated
Cognitive Errors: Just As
Complicated…But In A Different Way
Cognitive Error Categories

Faulty Knowledge

Faulty Data Gathering

Faulty Information Processing

Faulty Verification
Origins of diagnostic error in 100 patients
19% related
to Systems
Error
Didn’t expand
your differential
diagnosis…..
28% related
to Cognitive
Error
Forgot to f/u on the
blood cultures…
46% related
to both Systems
and Cognitive
Errors
Poor communication
among
consultants…..
Leape LL, et al. N Engl J Med 1991; 324(6): 377-84.
Graber ML. Franklin N. Gordon R. Diagnostic error in internal medicine. Archives of
Internal Medicine, 2005; 165(13): 1493-9.
Anchoring Bias



Also called “premature
closure”
the failure to continue
considering reasonable
alternatives after a primary
diagnosis is reached, is the
most common diagnostic
error
ie When the diagnosis is
made, the thinking stops
Croskerry, P. Acad Med 2003; 78:775-80.
Confirmation Bias
Confirmation bias
Tendency to look for confirming
evidence to support a diagnosis
rather than look for discomfirming
evidence to refute it (despite the
latter often being more
persuasive and definitive)
Absolutely!
Croskerry, P. Acad Med 2003; 78:775-80.
Availability
Availability bias
Judge things as being more likely
if they readily come to mind
Croskerry, P. Acad Med 2003; 78:775-80.
Unpacking Principle
The failure to elicit all
relevant information in
establishing a
differential diagnosis
that may result in
significant possibilities
being missed
Croskerry, P. Acad Med 2003; 78:775-80.
Framing Effect
The framing of the patient scenario, including the source and
where the patient is seen, influences the way the patient
is thought about
Croskerry, P. Acad Med 2003; 78:775-80
Diagnosis Momentum
Also known as “chartlore”- once diagnostic
labels are attached to
patients, they become
stickier and stickier
Croskerry, P. Acad Med 2003; 78:775-80.
Visceral Bias



Counter-transference
negative feelings towards a
patient may result in
diagnoses being missed
Common Types
»
»
»
»
Non-compliant patients
Homeless patients
Patients with chronic pain
Obese patients
Cognitive Bias Can Lead to Errors
in Diagnosis
How Do We Deconstruct Our
“Brick Walls”?
5 Basic Questions to Help Avoid
Cognitive Errors

What are traps I might fall into

What else can it be?

Is there anything that doesn’t fit?

Is there’s more than one thing going on?

Is this a case where I need to “slow down”?
Summary
Heuristics are important for efficiency of care
 Heuristics can also be used for expediency of care
that may compromise optimum care
 Cognitive bias is an important factor that can
adversely influence diagnostics
 Thorough problem lists and broad differentials can
mitigate some cognitive bias
 MD 305 rule: Minimum of 3 diagnoses, 2 organ
systems

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