About a week ago, I was helping my friend studying psychology. During that time, I learned many interesting things about different topics. The topic that caught my attention the most was the topic on as we increase in age, or intelligence decreases. I find this interesting because this made me think about my grandparents and I don’t recall any of them having a decrease in intelligence. Due to this, I wanted to find out if the statement, intelligence decreases as age increases, is true.

After a few search on the Internet, I came across something called The Seattle Longitudinal Study conducted by Schaie. The Seattle Longitudinal Study, apparently, stands as the most accurate research on intellectual maturation. This study started testing individuals from 1957 for a period of 30 years. The study group consisted of seven age groups ranging from 21-year-old college students to 63 year olds. Each of the volunteers was then given a variety of intelligence tests that tested inductive reasoning, numerical ability, spatial orientation, verbal understanding, and word fluency. Then Schaie would test the same group again in seven years (21 year olds were tested at 28, 63 years olds were tested at 70) and after that, he tested them again after another seven years (28 year olds were tested again at 35, 70 years olds were tested at 77). According to the article, as a result, “the Seattle Longitudinal study suggested that intellectual performance remained stable from age 21 to 56, but noticeable declines characterized individuals who were aged 63, 70, and 77.”

Even though this study did show that as we increase in age, especially after 63 years of age, intelligence decreases, the Seattle Longitudinal Study, however, rejected the theory that intelligence decreases as age increases. The reason why they rejected the theory is because this study did not find the scores of every older individual to decrease. “In fact, the majority (i.e., more than 65%) of the older adult groups did not experience any significant intellectual decline with aging as indicated by the stability of their scores across the five measures.”

As a result, Schaie concluded that a decrease in intelligence among older adults is not natural. Based on his conclusion, I believed that third variables play a huge part in this experiment. For the adults that did have a decrease in intelligence as age increased, I believe they are affected by third variables like poor nutrition, lack of social support, a lower level of education, or certain diseases. Of course we can’t ignore the possibility of chance in this experiment.

I believe the study was well conducted. However, I believe another similar experiment should be conducted, but this time with people of similar IQ range, similar health and wealth. This way most part of the confounding variables can be eliminated and will make the experiment more convincing. Overall, I agree with the conclusion that Schaie formed because if there were a decrease in intelligence, I would see it in my grandparents and other elder family members. What do you guys think?

Sources:

http://gero.usc.edu/AgeWorks/core_courses/gero500_core/psychology_lect/

http://psychology.about.com/od/cognitivepsychology/a/fluid-crystal.htm

http://mentalhealth.about.com/library/sci/1001/bloldsmart1001.htm