Understanding Cognitive Biases in Software Development

After years of referencing Wikipedia's tangled list of 175 cognitive biases, I've distilled them into a clearer framework that's particularly relevant for software teams.

The Four Core Problems Our Brains Solve

Every cognitive bias exists to help our brains handle these fundamental challenges:

1. Information Overload

We filter aggressively because there's too much information. In development, this means we notice:

• Things recently discussed in standups or code reviews
• Unusual bugs or surprising behavior
• Changes that confirm our existing beliefs about the codebase
• Flaws in others' code more easily than our own

2. Lack of Meaning

We fill gaps with assumptions and patterns. In tech, we:

• Find patterns in sparse data (even when they don't exist)
• Fill in missing requirements with stereotypes about users
• Assume familiar technologies are better than unfamiliar ones
• Think we know what teammates are thinking

3. Need to Act Fast

We jump to conclusions to avoid paralysis. This leads to:

• Overconfidence in our technical decisions
• Favoring immediate fixes over long-term solutions
• Continuing with sunk-cost projects
• Choosing simple solutions over complex but better ones

4. Memory Limitations

We simplify and generalize to remember key points:

• Edit memories of past incidents after the fact
• Form stereotypes about certain technologies or practices
• Remember only peak moments and endings of projects
• Store information differently based on how dramatically it was presented

The Downside

While these mental shortcuts help us function, they also create problems:

• We miss important information we've filtered out
• We imagine patterns and meanings that aren't really there
• Our quick decisions can be unfair and counter-productive
• Our memories reinforce existing biases

What This Means for Dev Teams

Understanding these biases helps us:

• Question our assumptions during code reviews
• Seek diverse perspectives in technical decisions
• Build systems that account for human cognitive limitations
• Create processes that slow down critical decisions when needed

The goal isn't to eliminate bias (impossible) but to recognize when our mental shortcuts might be leading us astray—especially during high-stakes technical decisions.

Cognitive biases are tools. They're useful in the right contexts, harmful in others. Since they're the only tools we've got for processing information, we might as well understand them.