Environmental Influence

Domestic Violence: Children are threatened when they witness violence between parents. They feel stressed and brain development will be harmed in three major ways. First, catecholamines and cortisol level will rise. Then, neurons in some brain regions will die. Third, intracranial volume decreases, which correlates with IQ. As a result, IQ is lowered (Koenen et al., 2003)
Malnutrition: Undernourishment creates chronic health problems and adversely affects intellectual development. First, it can induce brain damage. Most of them are reversible. Then, malnourished children lack energy, which decreases their contact with environment. Third, they explore fewer because of hindered physical development, which in turn get less stimulation from the environment. Lastly, parents tend to treat smaller-for-their-age children as if they are younger. They are not being challenged enough. Other environmental factor such as family income level and education level can either protect malnourished children from harmful effects of poor diet or worsen the effect (Brown & Pollitt, 1996).