"I've found the perfect candidate: he wears glasses, so he's bound to be thorough!

This may sound like a caricature, but we all tend to attribute qualities to a person on the basis of a first impression. This psychological phenomenon, known as the halo effect, unconsciously influences our judgements and can have a considerable impact, particularly in recruitment.

For example, a candidate who arrives at an interview well-dressed, smiling and self-confident will instinctively be perceived as competent and intelligent, even before their actual skills have been assessed. Conversely, another candidate, who is more reserved or stressed, may be judged to be less effective, even if his or her profile corresponds perfectly to the position.

This bias is often reinforced by confirmation bias, which leads us to look only for elements that validate our first impression rather than questioning it. For example, if a recruiter associates wearing glasses with rigour, the candidate's interview might be unconsciously geared towards validating this perception.

Conversely, a candidate arriving 10 minutes late and with a slightly sweaty forehead, because of an unforeseen event, could immediately be perceived as lacking in rigour and being disorganised. Even if he or she is usually punctual and methodical, the interview may then turn into an unconscious search for evidence to confirm this initial impression.

1. What is the halo effect?

The halo effect is a cognitive bias identified by the psychologist Edward Thorndike in 1920. It describes the tendency to generalise a positive or negative impression to all of a person's characteristics.

In recruitment, this means that a distinctive trait (such as good looks, natural charisma or great eloquence) can unconsciously influence the assessment of other more objective criteria, such as technical skills or experience.

Concrete examples:

• An extrovert and charismatic candidate may be perceived as a good leader, even if their management experience is limited.
  A well-groomed person may be seen as more organised and professional than a less presentable candidate.

2. The reverse halo effect: the horn effect

The horn effect is the opposite of the halo effect: a negatively perceived characteristic wrongly influences the overall assessment of a candidate.

For example:

• A shy person may be judged as lacking confidence, and therefore unsuitable for a position of responsibility, even if their technical skills are excellent.
• A candidate with speech difficulties may be perceived as less intelligent, even though this has nothing to do with their actual cognitive abilities.

Concrete examples from companies

In some companies, the halo effect has led to costly recruitment errors.

• Candidates recruited for their charisma have proved ineffective once in post.
• Others, rejected because of a bad first impression, could nevertheless have added real value to the company.

These biases also have an impact on diversity and inclusion. By unconsciously favouring certain profiles on the basis of subjective criteria, recruiters risk excluding qualified candidates from under-represented groups.

How can we limit the halo effect in recruitment?

To ensure a more objective assessment of candidates, here are some strategies for reducing the impact of the halo effect:

1. Use standardised assessment grids: Define precise criteria and assess each skill independently.
2. Use structured interviews: Ask all candidates the same questions to ensure a fair comparison.
3. Multiplying points of view: Involving several recruiters to limit the influence of individual judgements.
4. Use objective tests: Use practical assessments and simulations to measure candidates' real skills.
5. Be aware of your own biases: Make recruiters aware of cognitive biases so that they can better identify and limit them.
6. Use decision-support technologies: Use artificial intelligence to analyse applications more impartially.

The halo effect is a powerful cognitive bias that can distort recruitment decisions and lead to less relevant choices. By adopting more objective practices and diversifying assessment criteria, companies can reduce this bias and select candidates on the basis of their real skills, rather than superficial impressions.