Types of Bias: Understanding 16 Common Cognitive Biases

Our brains are remarkable pattern-recognition machines, but these same patterns can lead us astray through cognitive biases – systematic errors in thinking that affect our decisions and judgments. While the mechanisms and history of cognitive bias are fascinating, understanding how these types of bias are categorized helps us recognize them in our daily lives.

From the way we make decisions to how we remember events, cognitive errors can be grouped into distinct types of bias that reveal their impact on different aspects of our thinking.

Decision-Making Types of Bias

When we’re faced with choices, our minds employ shortcuts that can sometimes lead us down problematic paths. Decision-making biases represent some of the most impactful cognitive shortcuts, affecting everything from major life decisions to everyday choices. These types of bias include:

Anchoring Bias

The anchoring bias serves as a mental reference point that can skew our entire decision-making process. Imagine shopping for a car – if the first vehicle you see is priced at $50,000, you might perceive a $35,000 car as “cheap,” even if that’s still well above your intended budget. This initial number becomes an anchor that influences all subsequent judgments.

Confirmation Bias

Confirmation bias acts like a selective filter on reality, drawing our attention to information that supports what we already believe while conveniently helping us ignore contradictory evidence. A manager convinced that remote work reduces productivity might focus exclusively on employees who struggle with working from home while overlooking those who thrive in it.

Availability Heuristic

The availability heuristic makes us overweight recent or memorable information when making decisions. After hearing about a plane crash on the news, someone might choose to drive instead of fly, despite driving being statistically more dangerous. The vivid, easily recalled image of the crash overshadows less dramatic but more relevant statistics about travel safety.

Choice-Supportive Bias

Choice-supportive bias acts as a mental defense mechanism, leading us to retroactively justify our past decisions. Someone who purchased an expensive smartphone might emphasize its unique features while downplaying its drawbacks, simply because they made that choice. This bias helps us feel better about our decisions but can prevent us from learning from suboptimal choices.

Social Types of Bias

Our brains have evolved to navigate complex social environments, but this navigation system has its own glitches. Social biases influence how we perceive, judge, and interact with others, often without our conscious awareness. These types of bias include:

Ingroup Bias

The ingroup bias is a tribal tendency that leads us to favor and trust members of our own group while viewing outsiders with skepticism. It appears in subtle ways: office workers might automatically attribute better motives to colleagues from their own department, or sports fans might judge similar behavior differently depending on whether it comes from their team or the opposition.

Halo Effect

When one positive quality creates a rosy glow around everything else about a person. Attractive people are often assumed to be more competent, kind, and intelligent – a phenomenon well-documented in job interviews and performance reviews. A charismatic CEO might have their business decisions viewed more favorably, regardless of actual merit.

Fundamental Attribution Error

We’re quick to blame others’ mistakes on their character while excusing our own as circumstantial. This is an example of a type of bias known as the fundamental attribution error at work.

When a colleague misses a deadline, we might label them as “irresponsible,” but when we miss one, we point to external factors like traffic or technical issues. This bias creates a dangerous double standard in how we judge behavior.

Stereotyping

Perhaps the most pervasive social bias, stereotyping involves making snap judgments about individuals based on perceived group membership. While our brains use categorization to make sense of the world, these mental shortcuts can lead to unfair assumptions: expecting an older person to be tech-averse, or assuming someone’s interests or abilities based on their gender.

Memory Types of Bias

Memory isn’t a perfect recording of past events – it’s more like a story we’re constantly rewriting. Memory biases shape how we store, recall, and interpret our experiences, influencing both our understanding of the past and our future decisions. These types of bias include:

Hindsight Bias

Also known as the “I knew it all along” effect, hindsight bias makes past events seem more predictable than they really were. After a company’s stock soars, investors might claim they “saw it coming,” forgetting their uncertainty at the time.

This bias can make us overconfident in our ability to predict future outcomes and prevent us from learning from genuine surprises.

Self-Serving Bias

In the self-serving bias, we play editor with our memories, taking credit for successes while blaming failures on external factors. A student who aces a test might attribute it to their intelligence and hard work, while explaining away a poor grade by citing a noisy classroom or unclear instructions. This bias helps maintain our self-esteem but can prevent honest self-evaluation.

Source Confusion

Our brains are better at storing information than tracking where it came from. We might confidently share a “fact” we “read in a scientific study,” when it actually came from a social media post or casual conversation. This bias becomes particularly problematic in an age of information overload, where distinguishing reliable sources from questionable ones is crucial.

Peak-End Rule

When recalling experiences, we place disproportionate weight on the most intense moment (the peak) and the ending, while other details fade. A vacation might be remembered as “amazing” based on one spectacular day and a pleasant journey home, despite several days of mediocre experiences. This bias explains why painful experiences with positive endings often become fond memories.

Probability and Belief Biases

The human brain isn’t naturally equipped to handle probability and statistics – we evolved to make quick decisions based on limited information, not carefully calculate odds. These biases reveal how we misunderstand chance and misjudge our own knowledge and capabilities. These types of bias include:

Gambler’s Fallacy

This bias leads us to believe that random events “even out” in the short term. A roulette player might bet on red after seeing five blacks in a row, convinced that red is “due” to appear.

In reality, each spin is independent, and previous outcomes don’t influence future ones. This misunderstanding of probability affects not just gambling, but any situation involving random events.

Optimism Bias

Our tendency to believe we’re less likely to experience negative events than others. Most people think they’re above-average drivers, more likely to succeed in business, and less likely to face health problems than their peers. While optimism can fuel persistence, this bias can lead to poor risk assessment and inadequate preparation for potential challenges.

Base Rate Fallacy

We often ignore general probability in favor of specific, attention-grabbing information. When assessing whether someone is a librarian, we might focus on their quiet personality while ignoring the fact that there are far more salespeople than librarians in the population. This bias leads us to overweight compelling stories and underweight statistical evidence.

Dunning-Kruger Effect

A meta-cognitive bias where people with limited knowledge in a domain overestimate their expertise, while experts often underestimate theirs. Someone who just learned the basics of investing might feel confident making complex market predictions, while a seasoned financial analyst might be more likely to acknowledge market uncertainties.

This type of bias bias helps explain why confidence often doesn’t correlate with competence.

Other Common Types of Bias

Some other common types of bias that can affect your thinking include:

• Affinity bias
• Bias blind spot
• Projection bias
• Framing effect
• Overconfidence bias
• Loss aversion
• Sunk cost fallacy
• Serial position effect
• Just-world hypothesis
• Belief perseverance
• Negativity bias
• Empathy gap
• Groupthink
• Bandwagon effect
• Authority bias

Understanding Types of Bias

The categories of cognitive bias – decision-making, social, memory, and probability – reveal how our mental shortcuts can both help and hinder us. While these biases evolved to help our ancestors survive in a simpler world, they can misfire in our complex modern environment.

The good news is that awareness is the first step toward better thinking. By understanding these patterns in our thought processes, we can pause before making important decisions, question our quick judgments about others, fact-check our memories, and approach probability with more careful consideration.

This doesn’t mean we need to – or even can – eliminate these biases completely. Instead, knowledge of these mental shortcuts gives us the power to step back and ask:

• Is anchoring affecting my price negotiations?
• Am I judging someone through the lens of stereotypes?
• Have I really “known it all along,” or is that hindsight talking?
• Are my confident predictions backed by real expertise?

These questions won’t perfect our thinking, but they can help us navigate a world that demands increasingly sophisticated decision-making.

Sources:

Berthet V. (2021). The measurement of individual differences in cognitive biases: A review and improvement. Frontiers in Psychology, 12, 630177. https://doi.org/10.3389/fpsyg.2021.630177

Korteling, J. E. H., Paradies, G. L., & Sassen-van Meer, J. P. (2023). Cognitive bias and how to improve sustainable decision making. Frontiers in Psychology, 14, 1129835. https://doi.org/10.3389/fpsyg.2023.1129835

Saposnik, G., Redelmeier, D., Ruff, C. C., & Tobler, P. N. (2016). Cognitive biases associated with medical decisions: a systematic review. BMC Medical Informatics and Decision Making, 16(1), 138. https://doi.org/10.1186/s12911-016-0377-1