Can IQ Change Throughout a Person's Lifespan?
Introduction
Intelligence quotient (IQ) is often seen as a stable measure of cognitive abilities, but it can be influenced by various factors such as education, environment, and life experiences. Let's explore how IQ can change over time and the factors that contribute to these changes.
IQ as a Stable Measure
Traditional views of IQ suggest that it is a stable measure over time, but this is not entirely accurate. While an individual's IQ score may not drastically change, it can fluctuate due to improvements in skills or knowledge, changes in testing conditions, or even lifestyle choices such as reading regularly or engaging in recreational drug use.
The Impact of Education and Lifestyle
A study suggests that if you read one book every 2 weeks for an entire year, your IQ would go up. Conversely, smoking or doing drugs could lead to a decline in your IQ. This impact is not just about immediate changes; it can also reflect long-term cognitive changes over time.
The Role of Age
When you take an IQ test, your age is always an important factor. Your raw IQ increases until you are about 37 and then gradually declines. This is why IQ tests typically provide results based on age comparisons to avoid discrimination and make interpretations more straightforward.
The Debate on IQ Change
Rachel, a cognitive psychologist, shares her opinion that IQ can indeed change throughout life. Focus on education and self-enrichment can enhance cognitive skills, leading to better performance in IQ tests. However, she also states that the underlying intelligence, represented by the g factor, remains relatively constant unless influenced by external factors.
Understanding the g Factor
IQ is not the most accurate measure of intelligence, but rather a psychometric tool that attempts to capture the g factor, also known as Spearman's g factor or general intelligence. The g factor is further divided into two categories: fluid intelligence (gf) and crystallised intelligence (gc).
Fluid Intelligence (gf): This is the pure reasoning capacity of the brain and increases rapidly from birth, reaching its peak in the mid-20s. After that, it slowly declines.Crystallised Intelligence (gc): This is the acquired knowledge and skills that an individual accumulates over their lifetime and typically increases with age.
IQ Testing and Measurement
The most common IQ testing system today is the standard deviation system, usually calculated on a standard deviation of 15. Scoring an IQ of 100 indicates that you have performed better than 50% of the general adult population. Higher scores are associated with better performance in specific areas.
Sample IQ Scores and Interpretations
115 IQ: You have performed better than 84% of the general population.130 IQ: You have performed better than 98% of the general population.145 IQ: You have performed better than 99.9% of the general population.160 IQ: You have performed better than 99.997% of the general population.
It's crucial to note that most tests struggle to differentiate scores above the 99.9th percentile, so any score above 145 should be taken with caution. For children, a ratio IQ score is often used, which compares a child's actual mental performance to their expected performance based on their physical age. This can often lead to exaggerated scores, as there can be diverse developmental curves among children.
Understanding these nuances in IQ testing and measurement can provide a more comprehensive view of individual cognitive abilities and their development over time.