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Cognitive Biases in Testing
Srikanth S KrishnanSr. Director QAOracle India
What is a Cognitive Bias ?
It is the human tendency to make systematic errors in certain circumstances based on cognitive factors rather than evidence.
Heuristics
Statistical mis-estimates
Memory errors
Social Constructs
Tester’s Delusion Spots
Test Planning
Test Design
Test Advocacy
Anchoring
Guess the percentage of African Nations in the
UN.
Anchoring
Will you be happier if you get a 100% raise?
Bidding after stating the last 2 digits of social security number
Why are black pearls more expensive?
occurs when people consider a particular value for an unknown quantity before estimating that quantity
Effect on Estimation
New Feature vs. regression testing of existing features
Effect on Negotiation
Relativity
Would you mind walking 5 min to save $10 on a $ 50
pen?
Would you mind walking 5 min to save $10 on a $ 1000 suit?
Decoy Effect or Asymmetric dominance effect
Option A Option B
Coverage 400 300
Cost 3800 2000
Option A
Option B
Option C
Coverage
400 300 350
Cost 3800 2000 4500
People not only compare things, but also compare things that are easily comparable.
The Price of Ownership
Endowment Effect
How much would you pay for a Coffee Mug ?
Applies to ideas as well as objects.
The more effort you put into something the more ownership you feel. IKEA Effect
Ex. Manager from Finance
Test repository clean up
Which one will you get rid of?
(assume similar coverage)
Suite1 Created with 100 man days effort
Suite2 Created with 30 man days effort
Effect of Expectation
Confirmation bias: Self-Fulfilling Prophecy
How do you get more women in the orchestra?
Positive vs. negative Test cases.
Seeing patterns where none exist.
exist.
exist.
20
12
4
31
Influence of great UI.
Negativity Bias
More attention is given to negative than positive experiences
The lingering effect of a nasty bug.
Sunk Costs
Concorde Fallacy
“I have spent so much time doing the setups.”
Concorde Fallacy
Why test a build that has been obsoleted?
Paradox of Choice
Concorde Fallacy
More is not always better
Burn your bridges
Concorde Fallacy
Why don’t we keep this server just in case?
Procrastination
Concorde Fallacy
Choose your own deadline
Concorde Fallacy
The hockey-stick effort curve
Concorde Fallacy
Milestones and distributed deadlines
Resurrection to Rationality
overcoming
channeling
References and Acknowledgements
Predictably Irrational – Dan ArielyNudge – Thaler & SunsteinBlink – Malcolm GladwellSway – Brafman (Ori & Rom)Wikipedia
