Research Article

The Importance of
IQ.

Understanding why intelligence quotient matters across academic achievement, career success, health outcomes, and life satisfaction.

1 What Makes IQ Important?

Intelligence Quotient (IQ) represents one of the most reliable and valid psychological constructs ever discovered. Unlike many psychological measures, IQ scores demonstrate remarkable stability over time—test-retest correlations often exceed .90 across decades—and predict a wide range of real-world outcomes with considerable accuracy.

The importance of IQ extends far beyond academic settings. Research spanning over a century has consistently shown that cognitive ability serves as a foundational trait influencing success across virtually every domain of human endeavor. This doesn't mean IQ is destiny—environmental factors, motivation, personality, and opportunity all play crucial roles—but it does mean understanding your cognitive profile provides valuable insights for personal development and life planning.

Renowned psychologist Linda Gottfredson has described g (general intelligence) as "a highly general capability for processing complex information of any type." This capacity influences how quickly we learn, how effectively we solve problems, and how well we adapt to new situations—skills relevant to nearly every aspect of modern life.

2 Academic and Educational Outcomes

IQ is the single strongest predictor of academic achievement, surpassing factors like socioeconomic status, parental education, and school quality. Studies consistently find correlations of .50 to .70 between IQ and grades, indicating that roughly 25-50% of the variance in academic performance can be attributed to cognitive ability. Research by Deary et al. (2007) in the journal Intelligence provides comprehensive evidence for this relationship.

.70-.85
IQ-SAT Correlation
25-50%
Variance Explained
+2.5
Years Schooling per SD
  • Educational Attainment: Each standard deviation increase in IQ (15 points) is associated with approximately 2.5 additional years of education. Higher IQ individuals are more likely to pursue and complete advanced degrees.
  • Learning Efficiency: Individuals with higher cognitive ability typically acquire new knowledge and skills more rapidly. They require fewer repetitions to master material and can handle greater informational complexity.
  • Complex Problem Solving: Higher IQ enables better handling of abstract, multi-step academic problems across disciplines from mathematics to literary analysis.
  • Standardized Testing: IQ correlates strongly (.70-.85) with performance on standardized tests like the SAT, ACT, GRE, LSAT, and MCAT.
  • Academic Honors: Students with higher IQs are significantly more likely to graduate with honors, win academic awards, and gain admission to selective institutions.

3 Career and Occupational Success

IQ is a powerful predictor of job performance across virtually all occupations. The landmark meta-analyses by Hunter and Schmidt (1998) and subsequent researchers have established that general cognitive ability predicts job success with correlations of .50 to .60 for complex jobs and .20 to .30 for simpler roles.

The relationship between IQ and occupational success is particularly strong for jobs requiring learning, problem-solving, and adaptation to new situations. In knowledge-economy careers, cognitive ability becomes even more predictive as the complexity of work increases.

  • Job Performance: IQ predicts performance ratings, productivity measures, objective work samples, and supervisor evaluations. It is the single best predictor of job performance across all occupations studied.
  • Income: Research suggests each additional IQ point above the mean is associated with approximately 1-2% higher lifetime earnings. The top 1% of IQ (135+) earn on average 3-4 times the median income.
  • Occupational Prestige: Higher cognitive ability is strongly associated with entry into professional and managerial positions. The average IQ of physicians, engineers, and professors exceeds 125.
  • Training Success: IQ predicts how quickly and effectively employees can be trained for new roles, master new software systems, and adapt to organizational changes.
  • Leadership: Studies find moderate positive correlations between IQ and leadership emergence, particularly in complex organizational environments.
  • Entrepreneurship: While personality factors also matter greatly, higher IQ is associated with successful business formation and survival.

4 Health and Longevity

Perhaps surprisingly, IQ measured in childhood predicts longevity and health outcomes decades later. The "cognitive epidemiology" literature has documented robust associations between intelligence and mortality, with each 15-point increase in IQ associated with approximately 20% lower mortality risk.

The Scottish Mental Surveys of 1932 and 1947 tested nearly every 11-year-old in Scotland and have enabled researchers to track health outcomes over 70+ years. These studies consistently show that childhood IQ predicts adult health independent of socioeconomic factors. See Deary (2004) for an overview of cognitive epidemiology.

20%
Lower Mortality per SD
24%
Less Heart Disease
30%
Less Stroke Risk
  • Health Behaviors: Higher IQ is associated with better health decisions, including lower rates of smoking (correlation -.25), reduced substance abuse, better diet choices, and more regular exercise.
  • Medical Adherence: Individuals with higher cognitive ability better understand complex medical regimens, remember to take medications, and follow preventive care recommendations.
  • Accident Prevention: Higher IQ is associated with lower rates of accidental injury and death, likely reflecting better judgment in risky situations.
  • Cardiovascular Health: Research shows ~24% lower coronary heart disease risk per standard deviation increase in IQ.
  • Mental Health: While the relationship is complex, higher IQ generally provides protective effects against some mental disorders, though it may increase risk for certain conditions like anxiety.
  • Dementia: Higher childhood IQ is associated with reduced risk of late-life dementia, possibly through greater "cognitive reserve."

5 Social and Life Outcomes

IQ influences numerous aspects of daily life and social functioning. Research shows associations with relationship quality, civic participation, financial decisions, and overall life satisfaction.

  • Financial Literacy: Higher IQ is associated with better understanding of financial concepts like compound interest, risk diversification, and long-term planning, leading to greater wealth accumulation independent of income.
  • Decision Making: Cognitive ability predicts quality of decisions across domains from health to finance to personal relationships. Higher IQ individuals show less susceptibility to cognitive biases and better calibration of confidence.
  • Law-Abiding Behavior: Higher IQ is associated with lower rates of criminal behavior and incarceration. The correlation between IQ and criminality is approximately -.20 even after controlling for socioeconomic status.
  • Civic Engagement: More cognitively able individuals tend to participate more actively in democratic processes, including voting, following current events, and engaging in community organizations.
  • Relationship Stability: Some research suggests higher IQ is associated with lower divorce rates, possibly reflecting better conflict resolution and long-term planning.
  • Parenting: Higher IQ parents tend to create more cognitively stimulating home environments and invest more in their children's education.

6 The Limits of IQ

While IQ is an important predictor of many life outcomes, it's crucial to understand its limitations:

  • It's Not Everything: Personality traits (especially conscientiousness), motivation, social skills, creativity, and emotional intelligence all contribute to success independently of IQ.
  • Environment Matters: Opportunity, education quality, family support, and socioeconomic factors significantly influence outcomes regardless of cognitive ability.
  • Diminishing Returns: Beyond a certain threshold (often cited as ~120), additional IQ points contribute less to real-world success as other factors become more important.
  • Domain Specificity: High IQ doesn't guarantee success in every area—people can be cognitively gifted but struggle with specific skills or domains.
  • Malleability: IQ is not completely fixed. Early interventions, education, and challenging cognitive activities can influence cognitive development, particularly in childhood.

7 The Value of Understanding Your IQ

Knowing your cognitive profile offers several practical benefits for personal development and life planning:

  • Self-Understanding: IQ testing provides objective insights into your cognitive strengths and areas where you might need to compensate with extra effort or different strategies.
  • Career Planning: Understanding your cognitive profile can help guide educational and career decisions toward fields that match your abilities.
  • Learning Strategies: Identifying specific cognitive strengths and weaknesses enables tailored learning approaches. Someone strong in verbal but weaker in visual-spatial abilities might prefer reading to diagrams.
  • Realistic Expectations: A clear understanding of abilities helps set achievable goals and appropriate challenges—neither too easy nor impossibly difficult.
  • Identifying Potential Issues: Large discrepancies between cognitive domains can sometimes indicate learning disabilities or processing differences that benefit from early intervention.
  • Appreciation of Diversity: Understanding cognitive variation promotes appreciation for different types of intelligence and the various ways people can contribute to society.

ACIS provides a comprehensive cognitive assessment that goes beyond a single number, offering detailed insights into six distinct cognitive domains. This granular profile enables more nuanced self-understanding and targeted development strategies than a simple composite score alone.

8 Key Research References

The claims in this article are supported by decades of peer-reviewed research: