5 Reasons for Using Cognitive Assessments When Screening Job Candidates
Quick Answer:
Research shows that cognitive ability (aka Thinking Style or Critical Thinking Skills) is a strong predictor of job performance. It reveals who can handle a role’s complexity as it grows, not just today. It’s genuinely difficult to fake and its predictive power doesn’t plateau over time.
I’ll be straight with you on something I’ve noticed myself and that the research generally backs up: thinking style seems to be one of the more fixed traits a person has. You either have a certain level of raw cognitive horsepower, or you don’t, and I haven’t found solid evidence that it can be meaningfully trained up in adulthood the way a skill or a habit can. That’s not a life sentence to low-level work for anyone, and it’s definitely not a measure of someone’s worth. It just means it’s a piece of the puzzle worth being honest about rather than assuming everyone can be coached into the same cognitive range with enough effort and a good manager.
It's also important to note that not everyone needs to be at the top of critical thinking scale. Plenty of people build extraordinary careers on the strength of their behavioral traits and hard-won experience, without ever needing to be a rocket scientist.
But, failure to measure cognitive ability during the hiring process can have big negative consequences!
Many years ago, I managed a bank branch. One of the gals on my team, let's call her "Lucy," worked at the customer service counter. Lucy was lovely - pleasant, personable, detail-oriented, and a diligent worker. We both moved on from that branch and I never saw Lucy again.
Fast forward 20 years, I was coaching the Chief Operating Officer at a large hospital. Let's call him Jack. One day, Jack was lamenting over a financial analyst on his team. He was frustrated because she would do the analysis he asked her to do and produce the reports he asked her to produce, but she'd never take it a step farther. She didn't dive deeper into the data to understand the trends or the root causes of the results, nor did she ever make any recommendations for improvement. He was particularly struggling because she was a genuinely nice person who was always willing to help others.
I asked if he used an assessment during the candidate screening process and sure enough, he did. I told him to pull up the results so we could take a look. It wasn't surprising to me that her critical thinking skills were average. She was doing average thinking work like analysis and reporting. What was surprising to me was that it was Lucy! Her assessment results couldn't have painted a truer picture of her - kind, helpful, accommodating, a strong desire to serve, detail-oriented - perfect for the customer service role that I remember her doing so well. But, I also knew instantly that she was not a good fit for a tough, demanding COO who expected her to solve some pretty big problems.
Jack was irritated that he didn't put more credence into the assessment results. Underneath his icy, dominant exterior, Jack really had a big heart. He found Lucy a different role in the hospital that truly aligned with her strengths. Then, he hired a new analyst with stronger thinking skills. And, they all lived happily ever after.
This isn’t about ranking human value. It’s about matching people to roles where they’ll actually thrive. So, here's my rationale for why cognitive thinking should be assessed during the hiring process.
1. It’s One of the Most Researched Predictors in Hiring Science
Schmidt and Hunter’s landmark 1998 meta-analysis reviewed 85 years of selection research and found that general cognitive ability predicts job performance at roughly r = .51, substantially higher than traditional hiring signals such as education or years of experience. For context, education alone predicts performance at only about r = .10, and experience alone at around r = .18, with diminishing returns after roughly five years. Cognitive ability has held up as one of the strongest single predictors across nearly every occupation studied since.
2. It Gets Stronger, Not Weaker, When Paired With a Good Interview
More recent research has actually reframed this conversation in an interesting way. A 2022 reanalysis led by Paul Sackett suggested that structured interviews are a strong predictor of success, which is a meaningful update worth knowing about rather than ignoring. But here’s the part that matters most for how you should actually hire: pairing a cognitive ability assessment with a structured interview produces composite validity above .60, meaningfully higher than either tool alone. That’s exactly why I’ve never recommended leaning on an assessment by itself. It’s built to work alongside a strong interview process, not replace one.
3. It Shows Who Can Handle Tomorrow’s Complexity, Not Just Today’s Job
I recently worked on a project evaluating technicians across different levels of the same organization, and it turned into one of the cleanest examples I’ve seen of this in action. Behavioral traits across the group were genuinely all over the map, steady and urgent, reserved and outgoing, plenty of each doing well. Thinking style told a completely different story. As technicians moved into roles demanding bigger, thornier problems, their thinking style scores climbed right alongside the complexity of the work. The technicians who struggled at the higher levels weren’t struggling because of personality or attitude. They simply didn't have the cognitive bandwidth the more complex role demanded.
Cognitive assessments are an early warning system. If you’re hiring or promoting someone into a role where the complexity ramps up, knowing someone’s thinking style tells you whether you’re helping them grow into the job or setting them up to quietly drown in it while everyone around them wonders what went wrong.
4. It’s Genuinely Hard to Fake
Thinking style assessment questions can't be shaded toward a socially desirable answer. There’s a right answer to a numeric reasoning problem regardless of how a candidate wants to be perceived. Compare that to an interview, where a well-prepared candidate can rehearse compelling answers to nearly any behavioral question you’re likely to ask. There’s no equivalent script for a reasoning problem you’ve never seen before.
5. Its Predictive Power Doesn’t Quietly Plateau
Experience is a great predictor of performance for the first few years on the job, and then its usefulness levels off fast, with research showing diminishing returns after roughly five years. Cognitive ability doesn’t work that way. Research using large-scale military occupational data across 31 diverse jobs found that the validity of general cognitive ability in predicting job-specific performance stays remarkably stable across different levels of job experience, meaning it keeps mattering years into a role, long after “years of experience” has stopped telling you much of anything new. Put plainly, five years from now, a new-comer with strong thinking skills will likely outperform the twenty-year veteran with weaker thinking skills on the cognitively demanding parts of the job.
Quick Answers to What People Actually Ask Me
Does a lower thinking score mean someone is less intelligent overall? No. It measures specific things, like verbal and numerical reasoning, can someone separate assumptions from facts, can they draw valid conclusions from information. Those things matter for certain kinds of roles. It says nothing about creativity, past experiences on the job, emotional intelligence, work ethic, or dozens of other things that make someone valuable and contribute to their problem solving ability.
Can someone improve their score over time with practice or training? The bulk of the research, including large replication studies on working memory training, doesn’t support meaningful, lasting gains in fluid reasoning ability in adults, though people can absolutely get better at specific learned skills and knowledge over time. It’s a genuinely debated area in cognitive science, but the evidence currently leans toward “fairly stable” rather than “highly trainable.”
Can AI close the critical thinking gap for people? I think it's too soon to tell. Anyone can type a problem into ChatGPT and, after telling you how wonderful you are for asking the question, it will give you a solution to the problem. The catch is, you have to be smart enough to ask the right question and smart enough to critique the answer to ensure it makes sense. At least for today, AI can be a support, but I wouldn't rely on it to close the cognitive gap for an employee in a job that requires a high degree of critical thinking.
What is the difference between an IQ test and a cognitive test? A cognitive test is not the same as an IQ test, though all IQ tests are cognitive tests, but not all cognitive tests are IQ tests. An IQ test is a specific, standardized test that measures general intelligence compared to the population. Pre-employment assessments check for job-related skills for job success such as numerical reasoning, verbal ability, and problem solving.
Should thinking skills alone ever be the deciding factor in a hiring decision? No, and I’d say that about any single characteristic on any assessment. It’s one strong piece of a much bigger picture, weighted alongside personality traits, motivational interests, past experiences, references from others, a strong interview, and other factors. My recommendation is that assessment results should never account for more than one-third of the hiring decision.
Why wouldn't I want every employee to be at the top of the thinking scales? First, that rocket scientist that you want to hire will likely be bored to tears if they don't have rockets to build. Although every job comes with problems to be solved, those problems come in varying degrees. Aligning the level of the problem with the level of the employee's thinking skills contributes to greater levels of success and also fulfillment in the role. Second, somewhere along the way, you've probably run into someone who is just too smart for their own good. They have trouble relating to normal humans (like me) and they come across as too academic or intellectually isolated. Remember, it's all about fit and there's a place for everyone - maybe in your organization or maybe someplace else.
Where to Go From Here
Want to know more about how complexity thresholds get built into a role's target profile? Check out my post: "What is a Job Profile?"
Curious what this actually looks like on a real candidate? Download a sample PXT Select Comprehensive Selection Report or schedule a meeting with me to try PXT Select on your first candidate for free.
Stay Ignited!
