A study using data on reported homicides in Chicago 1994-2002 and two independent surveys of children and families in Chicago, has revealed that African-American children who were assessed directly after a local homicide occurred scored substantially lower on vocabulary and reading assessments than their peers from the same neighborhood who were assessed at different times. The impact of the homicide faded both with time and distance from the child's home. However, in both datasets, while the results were extremely strong for African Americans, there was no effect of local homicides for Hispanics. Because of the prevalence of homicide in the most violent neighborhoods in cities like Chicago, these results mean that some children spend about one week out of every month functioning at a low level. Whites and other ethnic groups were excluded from the study because they were almost never exposed to local homicides in the samples used.
 . The acute effect of local homicides on children's cognitive performance. Proceedings of the National Academy of Sciences [Internet]. 2010 ;107(26):11733 - 11738. Available from: http://www.pnas.org/content/107/26/11733.abstract