Bias catalogue
33 biases, classified by the phase they distort
Each entry carries a definition, a concrete software-architecture example, the impact on the decision, and debiasing techniques. Bias names can be deceptive — read the definitions before relying on recognition.
Observe
Gathering and presenting information about the decision context.
8 biasesInformation Gathering
Completeness
The perception of an apparently complete or logical data presentation can stop the search for omissions.
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Information Gathering
Confirmation
Often decision-makers seek confirmatory evidence and do not search for disconfirming information.
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Information Gathering
Information
Belief that furtherly acquired information generates additional relevant data, even when it evidently does not.
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Information Gathering
Levels-of-processing effect
That different methods of encoding information into memory have different levels of effectiveness.
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Information Gathering
Reference
The establishment of a reference point or anchor can be a random or distorted act.
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Information Gathering
Search
An event may seem more frequent because of the effectiveness of the search strategy.
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Information Presentation
Framing
Definition 1: The framing effect is an example of cognitive bias, in which people react to a choice in different ways depending on how it is presented.Definition 2: Events framed as either losses or gains may be evaluated differently.
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Information Presentation
Similarity
The likelihood of an event occurring may be judged by the degree of similarity with the class it is perceived to belong to.
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Orient
Interpreting and filtering information against prior knowledge and experience.
8 biasesInformation Filtering
Base rate fallacy
The tendency to ignore base rate information (generic, general information) and focus on specific information (information only pertaining to a certain case).
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Previous knowledge/experience
Availability Heuristic
Definition 1: The tendency to overestimate the likelihood of events with greater 'availability' in memory, which can be influenced by how recent the memories are or how unusual or emotionally charged they may be. Definition 2: The availability heuristic is a mental shortcut that relies on immediate examples that come to a given person's mind when evaluating a specific topic, concept, method or decision.
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Semblance
Similarity
The likelihood of an event occurring may be judged by the degree of similarity with the class it is perceived to belong to.
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Previous knowledge/experience
Functional Fixedness
Limits a person to using an object only in the way it is traditionally used.
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Previous knowledge/experience
Google Effect
The tendency to forget information that can be found readily online by using Internet search engines.
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Previous knowledge/experience
Law of the instrument
An over-reliance on a familiar tool or methods, ignoring or under-valuing alternative approaches.
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Previous knowledge/experience
Mere exposure effect
The tendency to express undue liking for things merely because of familiarity with them.
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Trends
Bandwagon Effect
The tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink and herd behavior.
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Decide
Ranking alternatives and committing to a course of action.
15 biasesComplexity
Attenuation
A decision-making situation can be simplified by ignoring or significantly discounting the level of uncertainty.
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Complexity
Hard-easy effect
Definition 1: Based on a specific level of task difficulty, the confidence in judgments is too conservative and not extreme enough. Definition 2: The hard-easy effect is a cognitive bias that manifests itself as a tendency to overestimate the probability of one's success at a task perceived as hard, and to underestimate the likelihood of one's success at a task perceived as easy.
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Complexity
Planning fallacy
Definition 1: The tendency to underestimate task-completion times. Definition 2: The planning fallacy is a phenomenon in which predictions about how much time will be needed to complete a future task display an optimism bias and underestimate the time needed.
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Complexity
Time-saving bias
The time-saving bias describes people's tendency to misestimate the time that could be saved (or lost) when increasing (or decreasing) speed.
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Complexity
Parkinson's law of triviality
The tendency to give disproportionate weight to trivial issues. Also known as bikeshedding.
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Complexity
Well travelled road effect
Underestimation of the duration taken to traverse oft-traveled routes and overestimation of the duration taken to traverse less familiar routes.
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Nature of invention / trends
Bandwagon Effect
The tendency to do (or believe) things because many other people do (or believe) the same. Related to groupthink and herd behavior.
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Nature of invention / trends
IKEA effect
The tendency for people to place a disproportionately high value on objects that they partially assembled themselves, such as furniture from IKEA, regardless of the quality of the end result.
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Previous knowledge / experience
Habit
An alternative may be chosen only because it was used before.
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Previous knowledge / experience
Law of the instrument
An over-reliance on a familiar tool or methods, ignoring or under-valuing alternative approaches.
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Previous knowledge / experience
Mere exposure effect
The tendency to express undue liking for things merely because of familiarity with them.
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Strategy
Test
Some aspects and outcomes of choice cannot be tested, leading to unrealistic confidence in judgement.
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Strategy
Hyperbolic Discounting
Discounting is the tendency for people to have a stronger preference for more immediate payoffs relative to later payoffs. Hyperbolic discounting leads to choices that are inconsistent over time.
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Strategy
Inconsistency
Often a consistent judgement strategy is not applied to an identical repetitive set of cases.
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Nature of invention / trends
Negativity
Definition 1: Psychological phenomenon by which humans have a greater recall of unpleasant memories compared with positive memories.Definition 2: The negativity bias refers to the often-asymmetrical way we perceive the negative and the positive.
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Act
Implementing the decision — and the post-decision rationalisation that follows.
2 biases