"As soon as he walked into my office, I knew he was the right candidate," recalls Paul, Sales Director at an industrial SME. "He had that commercial energy we were looking for. He was well dressed, spoke with confidence, and had that firm handshake that inspires trust."
Six months later, the same candidate was dismissed for underperformance. Despite his apparent charisma, he failed to win a single new client and created constant friction with the technical team. Paul was left with a troubling question: how could he have been so wrong about someone who had made such a strong first impression?
This story highlights a fascinating paradox of human psychology applied to recruitment. While our brain is capable of processing vast amounts of information, it also relies on mental shortcuts that can lead to major judgement errors. These shortcuts, known as cognitive biases, deeply and often unconsciously influence hiring decisions.
The recruiter’s brain: a shortcut machine
To understand why interviews often mislead us, we need to look at how decision-making works. According to psychologist Daniel Kahneman, our brain uses two modes of thinking:
- System 1 is fast and automatic. It processes information in milliseconds, relying on past experiences, emotions, and mental associations.
- System 2 is slower and more analytical. It enables us to solve complex problems and make deliberate decisions — but it requires significant mental effort. As a result, we tend to default to System 1 when possible.
In interviews, System 1 kicks in the moment we meet a candidate, forming a first impression within seconds — based on appearance, tone of voice, posture, and many other subtle cues. This initial impression then heavily shapes how we interpret everything the candidate says or does throughout the interview.
The biases that sabotage your recruitment decisions
Understanding the general mechanics of cognitive bias is not enough. To truly improve the quality of interviews, we must learn to spot the most common recruitment-specific mental traps.
Here are five of the most harmful:
1. The halo effect: when one trait outshines the rest
This is perhaps the most widespread interview bias. It leads us to assess a candidate’s overall ability based on a single strong attribute. For instance, a well-spoken candidate may be perceived as more intelligent, trustworthy, or competent — even if those traits have no real connection to their communication skills.
Laura, a marketing manager, fell into this trap when hiring a developer. Impressed by his command of a cutting-edge programming language, she overlooked his poor collaboration and time management skills. The result? A brilliant technician who blocked progress by failing to work as part of a team.
2. Confirmation bias: seeing what we want to see
Confirmation bias drives us to seek out and interpret information in ways that support our existing beliefs. In interviews, this means we often ask questions that validate our first impression instead of objectively assessing the candidate.
If you feel positively about someone, you’ll unconsciously frame questions to reinforce that view. You’ll highlight successes, gloss over failures, and interpret ambiguous responses favourably. The opposite occurs with a negative first impression — you focus on flaws and doubt even sincere answers.
This explains why two interviewers can form completely opposing views of the same candidate: each unconsciously shapes the interview to confirm their initial judgement.
3. Similarity bias: hiring in our own image
We naturally gravitate towards people who resemble us. While this may be helpful in social settings, it becomes problematic in recruitment. Without realising it, we favour candidates who share our background, communication style, interests — even our dress sense.
Similarity bias helps explain why some companies struggle to build diverse teams. When recruiters unconsciously select candidates who mirror themselves, they perpetuate the same personality types and career paths — reducing cognitive diversity within the organisation.
Mark, HR Director at a consultancy, became aware of this bias when he realised he was consistently hiring graduates from his own business school. "I thought I was being objective," he explains, "but I was actually giving preference to profiles that reminded me of myself."
4. Overconfidence: overestimating our judgement
Most recruiters overestimate their ability to assess candidates. This overconfidence leads them to place excessive weight on subjective impressions and dismiss more objective tools.
Studies show that experienced recruiters are no better than beginners at predicting future job performance through unstructured interviews. Yet their confidence in their judgement grows with experience — creating a risky gap between perception and actual ability.
5. Attribution error: confusing character with context
This bias causes us to attribute someone’s behaviour to their personality, rather than external factors. In an interview, a candidate’s nervousness may be seen as a sign of weakness or lack of confidence — when in fact it’s simply a natural response to stress.
Paradoxically, we tend to justify our own behaviour through context. If we're late to an interview, it’s due to traffic. But if the candidate is late? Clearly, they’re disorganised.
This inconsistency seriously distorts our judgement.
How to structure interviews to reduce bias
Improving interview quality takes more than awareness. Good intentions alone won't overcome unconscious mental shortcuts. Structural safeguards are essential.
Here’s how:
- Standardise the interview process. Remove improvisation. Clearly define the competencies and behaviours you want to assess, and prepare targeted questions for each. Structured interviews ensure every candidate is evaluated on the same basis.
- Focus on behavioural questions. Ask for real-life examples, not hypothetical responses. Instead of: “How would you handle a difficult client?” Ask: “Tell me about a time you dealt with a difficult client. What did you do, and what was the outcome?”
- Use a standardised scoring grid. Define in advance what constitutes an excellent, good, average, or poor response for each criterion. This promotes consistency and enables fair comparisons between candidates.
- Involve multiple assessors. Having more than one interviewer reduces the impact of personal bias. When multiple people independently evaluate the same candidate using shared criteria, subjective distortions are diluted and predictive accuracy increases.
- Separate information gathering from decision-making. Don’t decide on the spot. Review notes with a clear head, compare candidates objectively, and consult other opinions before making a final choice.
Psychometric assessments: a necessary complement
Integrating scientifically validated assessment tools alongside structured interviews dramatically improves predictive accuracy.
These tools measure aspects that interviews can't reveal — cognitive abilities, interpersonal style, and deep motivation. They replace guesswork with objective data on real potential. By using standardised benchmarks, they also reduce subjectivity and eliminate many disagreements between recruiters.
Importantly, their predictive power is proven: candidates selected using appropriate assessments are significantly more likely to succeed and stay in their role.
This benefits everyone involved :employers hire the right people, candidates are evaluated fairly, teams gain better-aligned colleagues.
Recruitment is the art of balancing the human with the scientific — intuition with prediction, and experience with data.
Want to learn how to structure interviews and limit bias in your hiring process?
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