Bias and perception errors influence every assessment. Part 1 explains the basics and sources of error – for more awareness in the selection process.
Introduction
Personnel selection is a sensitive area. Decisions in this field have long-term consequences – for companies as well as for candidates. No matter how carefully a selection process is designed, perception errors and unconscious biases can significantly distort it. They creep in quietly, act subtly – and yet lead to serious misjudgements. In this first part of this blog series, we explore the theoretical foundations and classify the most important types of assessment errors. This knowledge forms the basis for implementing tangible measures to avoid bias in Part 2.
What are assessment errors?
An assessment error occurs when judgments are not based on objectively observed behaviour but are distorted by other influences. This can happen unconsciously through selective perception or stereotypical assumptions, or consciously and strategically – for example, when managers deliberately portray their employees more favourably to present their department in a good light.
Main categories of assessment errors
Research essentially distinguishes three categories: deception, distortion, and failure.
- Deception usually arises from misperception and memory errors. Our brain never perceives the full reality but constantly filters and interprets. Even small details can cause us to remember a situation differently than it actually occurred.
- Distortion refers to systematic shifts in judgment. It’s not about missing memory but about tendencies that steer our assessment in a particular direction. Examples include the leniency effect, where candidates are judged too favourably, or the sympathy effect, where someone is rated more positively simply because we personally like them.
- Failure occurs when consciously irrelevant criteria influence the evaluation. This is particularly critical because it involves not only unconscious mechanisms but also intent. Examples include strategically “protecting” certain team members or deliberately downgrading others to strengthen one’s own position.
Typical perception distortions in detail
The halo effect is particularly well-known: a single, striking trait overshadows the entire judgment. For instance, a rhetorically strong candidate may be assumed to be analytically capable – even though this hasn’t been observed. Similar effects include the primacy and recency effects, where the first or last impression is overvalued, and the stickiness effect, where earlier judgments linger too long.
Other distortions arise from sympathy or antipathy, proximity and hierarchy relationships, or deeply rooted stereotypes. We all know situations where our image of people is shaped by their origin, gender, or role – even when these traits are irrelevant to actual performance.
Systemic and personal sources of error
Errors don’t just arise in the observer’s mind but also within the structures themselves. Unclear or excessive criteria in interviews, irrelevant standards, or long intervals between observation and assessment also lead to distorted results. In addition, there are personal influences that come into play. Some observers project their own traits onto others or unconsciously apply their individual standards instead of aligning with the defined requirement profile.
Conclusion: awareness is the first step
The multitude of these errors illustrates the following: perception distortions are not marginal issues but a central challenge in personnel selection. Those who understand the mechanisms can reflect on them – and consciously counteract them in the next step. That’s exactly what Part 2 will address: how to design interviews to reduce bias and make decisions fairer.
Article written by Nicole Handschuh, MA, CFR Global Executive Search Austria
Photo: shutterstock