Wednesday, October 24, 2012


                                                Defining Intelligence
I would define intelligence as a range of cognitive abilities that contribute to adaptability as well as the capacity to contribute to and alter the environment, specifically to make it more functional, enjoyable, comfortable, and understandable. Conventional wisdom tells us that necessity is the mother of invention. Throughout history, when the environment was challenging, uncomfortable, or mysterious, people sought to alter, augment, and understand it.

                                   Environmental Effects on Intelligence
Considering the effects of the environment in a different way, culture has a tremendous effect on intelligence as well. Howard Gardner might say that culture influences which type of intelligence becomes salient to individuals within the culture (Gardner & Hatch, 1989). For example, family has traditionally been one of the most salient aspects of Hawaiian culture. So, when Europeans and Americans were prioritizing science and formal education in the early 19th century, generally speaking, the Hawaiians were not. It was not because one group was more intelligent than the other, but because of the importance placed on different goals. In families, too, ideas or goals that are important to the parents may become salient for the children. Consider families in which one of the parents is a doctor and then 3 of the 4 children become doctors. Becoming a doctor was likely not a genetic predisposition, but because of the importance placed on medicine, the children became doctors.

Heredity influences intelligence, although the jury still seems to be out regarding just how much it does. Adoption studies on the heritability of intelligence have been inconclusive (Santrock, 2008). I found it particularly interesting that some research indicates as people grow older, intelligence is driven more by personal choices than by the effects of the others (Santrock, 2008). It was disturbing to read that underprivileged children may experience long-term effects from living in poverty and neglect (Bigelow, 2006). Even when these issues were addressed when the children entered school, it was too late even when special interventions were implemented.

Although some evidence is mounting for genes as they influence executive and other cognitive functions, research regarding particular genes and how and what they affect to create individual differences in intelligence is unclear (Dreary, Spinath, & Bates, 2006). There have been, however, chromosomal regions associated with learning abilities, although this does not imply a genetic link (Kovis & Plomin, 2008).

It may be appropriate, at least at this time, to acknowledge the apparently powerful influence the environment wields on individual intelligence as well as intelligence of whole peoples. I found it interesting that g (general intelligence) seems to have an overall influence, or perhaps an underlying influence on the results of cognitive domains, such as measured by the Wechsler Adult Intelligence Scale III (Dreary, Spinath, & Bates, 2006). So, in other words, if a person is basically intelligent, they will show similar intelligence across those specific cognitive domains.

As far as the effects of intelligence on physical, cognitive, and socio-emotional development, during childhood and adolescence, peer relationships have a significant impact on the overall development of the individual (Estell et al., 2006). For example, children with learning abilities seemed to be more isolated (because of less social acceptance) than average students. Isolation alone would affect cognitive and socio-emotional development, and using the same example, if the child did not want to engage in physical play because of the isolation, it might delay physical development as well. When children are excluded from peer relationships, it may set them up for a life-long social deficiency, although no definitive longitudinal research exists to clarify the long-term effects of such isolation (Estell et al., 2006). Estell et al. (2006) found no such effects.

As far as the effects of influence and genetics on intelligence, I found it particularly interesting that "shared environmental influences were stronger for adolescents from poorer homes, while genetic influences were stronger for adolescents from more affluent homes" (Harden, Turkheimer, & Loehlin, 2007, p. 273). Perhaps this says that when the environment is optimal, the individual's unique ability to learn is more easily expressed. For example, in a household of higher economic status, abundant resources, parental guidance, less stress, and good nutrition may all contribute to individual success.


Bigelow, B. J. (2006). There’s an elephant in the room: The impact of early poverty and neglect on intelligence and common learning disorders in children, adolescents and their parents. Developmental Disabilities Bulletin, 34(1/2), 177–215.

Deary, I. J., Spinath, F. M., & Bates, T. C. (2006). Genetics of intelligence. European Journal of Human Genetics, 14(6), 690-700. doi: 10.1038/sj.ejhg.5201588

Estell, D. B., Jones, M. H., Pearl, R., Van Acker, R., Farmer, T. W., & Rodkin, P. C. (2008). Peer Groups, Popularity, and Social Preference: Trajectories of Social Functioning Among Students With and Without Learning Disabilities. Journal of Learning Disabilities, 41(1), 5-14. doi: 10.1177/0022219407310993

Gardner, H., & Hatch, T. (1989). Multiple intelligences go to school: educational implications of the theory of multiple intelligences. Educational Researcher, 18(8), 4. doi: 10.2307/1176460 [Note: since the ERIC database has limited availability at this time, please see the following website for this article:]

Harden, K. P., Turkheimer, E., & Loehlin, J. C. (2007). Genotype by Environment Interaction in Adolescents’ Cognitive Aptitude. Behavior Genetics, 37(2), 273-283. doi: 10.1007/s10519-006-9113-4

Kovas, Y., & Plomin, R. (2007). Learning abilities and disabilities: Generalist genes, specialist environments. Current Directions in Psychological Science, 16(5), 284–288. doi: 10.1111/j.1467-8721.2007.00521.x

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