Cognitive Heuristics
Vignesh Narayanan, M.D
Denver Health Medical Center
“An expert is a person who has made all the
mistakes that can be made in a very narrow field”
- Neils Bohr
I think, therefore I am
- Descartes,1664
Heuristics- definition
‘Heuriskein’ – ‘to find’ or ‘discover’ (Greek)
subconscious rules of thumb
shortcuts in diagnostic reasoning
‘Eureka’ has the same origin
Case presentation
63 y.o female, could speak only Spanish
CC: chest pain, progressive dyspnea
HPI: Chest pain X 2 wks
 sub-sternal, recurrent, episodic
 non-radiating, non-exertional
 worsened by deep inspiration
Other complaints:
 progressive dyspnea x 2 wks
 non-productive cough, no orthopnea/PND
 subjective fevers – 3 wks
Case: continued
Past medical history
 diabetic, hypertensive
 osteomyelitis of L- 5th toe, amputation 2 mos PTA
 CHF: diastolic dysfunction, EF > 55%
 CKD: baseline creatinine of 1.6
 lasix 120 mg BID, stopped 2 wks PTA
 metoprolol, amlodipine, hydralazine, rosuvastatin
 glargine & lispro
Case: continued
 amputation of L- 5th toe 2 mo PTA
Social history
 life long non-smoker, no alcohol
Family history
 mom with ‘heart problems’ NOS
 ten children
No allergies
Case: continued
 vitals: T:36, HR: 71, BP: 100/75, RR: 18
 normal JVP, normal cardiac exam
 bilateral diffuse crackles
 no edema of ext’s
 left 5th toe amputation site- normal
 Na: 126, BUN: 48, Creat: 1.9
 WBC: 11K, TnI: normal
 CxR: consistent with pulmonary edema
 EKG: NSR, no new changes
Case: initial A & P
Chest pain/cough
pleuritic in nature
c/w acute bronchitis- p.o azithromycin
SOB: Pulmonary edema unlikely given nl JVP
“dry” by labs- hyponatremia, BUN/creat ratio
? ILD- check PFT’s, HRCT, pulmonology consult
Acute on chronic renal failure: Likely volume depletion
check UA, U.lytes, U.Osm
substantiated by hyponatremia – IVF 500 ml NS
Subjective fevers, mild leukocytosis: occult infection ?
recent osteomyelitis- amputation site- well healed
check UA, ESR, CRP
Case: hospital day # 1
Improvement in symptoms
Complaint: pain over left temple & behind ear
 HR: 81, BP: 105/60, RR: 18, Sat: 92% 2L NC
 B/L diffuse crackles
 Na 135, creat 1.8, WBC: 11K
 CRP: 170, ESR: 110
 dyspnea, hypoxia, diffuse crackles- ? ILD
 pain L temple, elevated ESR, CRP- ? Temporal arteritis/PMR
 HRCT, PFT’s, rheumatology consult, echo
Case: hospital day # 2
More pain L temple/behind ear
More SOB than admit
nl vitals, 93% 4L NC
b/l diffuse crackles
Other labs
UA: 21-50 WBC
restrictive lung defect
no ILD
b/l pleural & moderate
pericardial effusions
coronary LAD calcification
pleuro-pericardial effusions,
temple pain, high ESR,
suspect CVD
echo for dyspnea
Case: hospital day # 2
 no evidence of CVD by history or exam
 alternate etiology for high CRP/ESR- r/o infection
 tap pleural effusion, check labs
 HRCT, PFT abnormalities likely due to CHF/pulmonary edema
 diuresce with IV lasix
Remaining hospitalization
Infection W.U
 sinus CT: nl mastoid
 foot X ray- no OM
Treated for UTI
Dyspnea, O2 sat
 much better with lasix
global hypokinesis
EF lower than 2 mos ago
Discharged on day 4
 Diastolic failure with
pulmonary edema
 Atypical chest pain
 Acute on CKD
2 days after discharge
Outside hospital
 chest pain, dyspnea
Cardiac arrest in ED
Coronary angiogram
 near total block of LAD
 doing well
elderly woman with
Chest pain
investigated for
several diagnoses
(ILD, CVD, Infection)
discharged with
alternate diagnosis
(diastolic CHF)
eventually diagnosed
with different
disease (critical CAD)
Missed diagnosis
Cognitive Psychology (of diagnosis )
Why we take shortcuts
ER doctor
Tom Brady
Lack of time
 rationality is bounded
Lehrer. How We Decide. HMH Press; 2009
Simon HA. Annu Rev. Psychology 1990; 41:1-19
Heuristics: ‘Shortcuts’ in diagnostic reasoning
Pitfalls are
repetitive &
Reduce time, deliberation
Wrong conclusions
Shortcuts in reasoning
Fever, cough,
chest pain =
Acute PE
‘Availability’ heuristic
Does the English language have
more words that start with the letter ‘r’
more words that have the letter ‘r’ in the third
Tversky & Kahneman- Cognitive Psychology. 1973;5: 207-32
‘Availability’ Heuristic
Ease of recalling past cases
 likelihood judged by easily ‘available’ past eg’s
More convenient than collecting & memorizing
Common diagnoses
are common
High CRP =
Un-common diagnoses
not considered
High CRP =
CAD risks
‘Anchoring’ Heuristic
First impression - Best impression?
Easier than constantly
re-integrating evidence
Anchored on lab
(Hyponatremia, CRP)
Lack of one finding
(Elevated JVP)
Failure to check for
disconfirming evidence
‘Framing’ Heuristic
atypical CP, serositis
suspected ILD ,temple pain
elevated ESR, CRP
Collagen vascular Dz
DM, recent toe OM
mastoid pain: ? sinusitis
abnormal UA, high CRP
Infectious process
atypical angina, CAD risks
new decrease in EF, pulm edema
calcified LAD, high CRP
Serious CAD
Other heuristics, biases
‘Blind Obedience’:
 Technology
Superior authority
PFT “restrictive lung disease”
rheumatology- “consider infection”
‘Premature Closure’
 reluctance to pursue alternate diagnoses
 using evidence that seems confirmatory
 dismissing evidence that is contradictory
Avoiding heuristic biases
Problems to acknowledge
Many clinicians are unaware of their error*
 too distal in time or place
 lack of effective feedback
 declining autopsy rates (<10%)
Sense of pessimism in the literature
 “cognitive errors are high hanging fruits”
 “the search for zero error rates is doomed from the
*Redelmeier- Ann Intern Med 2005;142:115-120
** Berner & Graber- Am J Med 2008;121:S2-S23
Strategies to minimize heuristic bias
Diagnostic error
- pay more attention
- be thorough
- practice more
- don’t forget this next time
Cognitive psychology
- awareness about
heuristic biases
- adding safeguards
against reflexive decision
Strategies to minimize heuristic bias
Gordian Knot
2 core strategies
Cognitive forcing
Strategy 1: Meta-cognitive training
Meta-cognition: “thinking about thinking”
“If at first the idea does not sound absurd, then there is no hope for it ”
- Albert Einstein
2 processes occurring simultaneously
 awareness of learning process to monitor progress
 adaptive strategies based on progress
Requires the clinician to
 stand apart from his/her own thinking & observe it
 recognize opportunities for intervention
Croskerry- Ann Emerg Med. 2003; 41: 1
Crystal ball experience
This plan is proven faulty
& does not work. Please
devise an alternate plan
Promotes open minded thinking
Helps to ‘step back’ and rethink
Ensures multiple possibilities are considered
Graber et al. Acad Med. 2002;77(10):981-92
Mitchell DJ- J Behav Decis Making. 1989;2:25-38
Strategy 2: Cognitive forcing
“Deliberate, conscious selection of a particular
strategy in a specific situation to optimize
decision making and avoid error”
Croskerry- Ann Emerg Med. 2003; 41: 1
Some ‘pills’ for our cognitive ‘ills’
Clinical shortcut
Corrective strategy
Easy recall
Decrease reliance on memory
verify facts - read more
1st impression
Reconsider in light of new data,
seek 2nd opinions
Subtle wording
Play devil’s advocate
‘Blind obedience’
Deference to authority
Re-confirm human work/ test accuracy
‘Premature Closure’
Narrow belief
“What is the diagnosis that I do not want to
Reidelmeier D. Ann Intern Med 2005; 142(2): 115-120
Croskerry P. Acad. Med 2003; 78: 775-780
Experts might feel like…
Cognitive short-cuts:
due to lack of time & bounded rationality
Double edged swords
Overcome by
metacognition & cognitive forcing
“Too often the shortcut, the line of least resistance, is
responsible for evanescent and unsatisfactory success”
- Louis Binstock

Mortality & Morbidity Conference