What is intelligence, really? Why is the G-factor so intriguing? And what is the purpose of aptitude tests? In just a few minutes, you’ll understand the different forms of intelligence and be able to explain how utilizing them can make a hiring process more cost-effective and efficient.
A step back in time
British psychologist Charles Spearman introduced the concept of the G-factor, a single score representing an individual’s general cognitive abilities (general intelligence). Psychologist Raymond Cattell expanded on this concept, distinguishing between fluid intelligence and crystallized intelligence. Fluid intelligence is innate—it’s the ability to recognize patterns, see relationships, learn, and reason abstractly. It involves understanding through logic before committing information to memory. Crystallized intelligence refers to the accumulation of knowledge and experience and the ability to apply them effectively.
The G-factor in everyday life
Both types of intelligence are used daily. For instance, solving a math exam requires understanding the meaning of symbols like “+” or “%” (crystallized intelligence) and devising a logical strategy to solve problems (fluid intelligence in action). Fluid intelligence helps solve new problems, while crystallized intelligence applies knowledge and experience. Aptitude tests used in assessments primarily measure fluid intelligence.
What is intelligence, and what do aptitude tests measure?
Intelligence isn’t a singular entity. It encompasses abilities like learning new information, solving problems, discovering patterns, handling abstract and complex matters (fluid intelligence), and applying knowledge and experience (crystallized intelligence). During an assessment, a sample of these abilities is evaluated. Aptitude tests measure fluid intelligence, providing insight into general cognitive ability (general intelligence or “g”). Assessment psychologists are particularly interested in the G-factor because it correlates with performance outcomes. But what does this factor signify in practice? Does someone with a low G-factor behave differently than someone with a high G-factor, and why is it considered so critical in the selection process?
What does science say?
About 20 years ago, two researchers aggregated findings from 85 years of studies on intelligence and job performance. They discovered that intelligence is the best predictor of workplace success. More recent research (2023) has nuanced this view, showing that intellectual abilities aren’t the sole, dominant predictor of success but remain one of the most important factors. Smarter individuals perform better because they process information faster (“processing speed”). They learn quickly, connect ideas efficiently, and handle complexity better. As the complexity of a job increases, the importance of intelligence grows.
An analogy for clarity
Think of two computers: one has an Intel Core i9 processor (top-tier) and the other a Pentium 2 processor (from 1997). A faster processor can perform more calculations per second, but not all tasks require this speed. Complex video editing does, while browsing the web or typing doesn’t. Similarly, fluid intelligence (processing power) enables faster task execution, but it’s not everything. Software, stored files, and shortcuts (crystallized intelligence) also play a role. A Pentium 2 may have less potential but can compensate with the right software and setup.
Why aptitude tests are useful
Aptitude tests measure how someone handles complexity under time constraints. To ensure fairness, they present abstract problems involving words, numbers, and shapes rather than realistic scenarios. These tests mimic real-life cognitive processes: absorbing environmental information, filtering it, identifying patterns, drawing conclusions, and applying existing knowledge. Among all assessment tools, aptitude tests have a strong track record for predicting workplace success. However, their predictive relationship with job performance isn’t one-to-one. Some individuals with low test scores still perform well, though the likelihood decreases as scores drop. For a comprehensive understanding of a candidate’s personality, motivations, leadership style, and communication skills, a full assessment conducted by a psychologist is advisable. However, in many cases, aptitude tests combined with personality and motivation questionnaires provide substantial insights into candidates. Such tools offer a quick return on investment by making recruitment processes more efficient.