In helping to understand the concepts here, we have to understand a few terms used. For starters, the word ‘cognition’ is the set of mental abilities or processes that allow us to understand the world and how to act in it. Cognitive abilities are brain-based skills we need to carry out any task from the simplest to the most complex. They have more to do with the mechanisms of how we learn, remember, problem-solve and pay attention, rather than with any actual knowledge. For instance, answering the telephone involves perception (hearing the ring tone), decision making (answering or not), motor skills (lifting the receiver), language skills (talking and understanding language), social skills (interpreting tone of voice and interacting properly with another human being).
A recent scientific paper in the journal ‘Psychological Science’ (Hodson & Busseri, 2012) considered that cognitive abilities had been overlooked as an explanation of prejudice. They undertook a study to determine to what extent it has such an effect, taking account of education and socioeconomic status, so as not to bias the results. They found that indeed, cognitive ability is a reliable predictor of prejudice.
This means that the poorer a person is in their cognitive abilities, the more likely they are to be prejudiced against other groups (different ethnic or religious groups, homosexuals etc.). They also found that a lower general intelligence in childhood predicts greater racism in adulthood and adherence to conservative ideology.
As a response to this, they suggested that the understanding of intergroup bias is a first step in addressing social inequality and prejudice. They also suggested that exposing right-wing conservative ideology and organising intergroup contact may be a way to decrease this prejudice.
See:
Hodson, G. & Busseri, M.A., 2012. Bright minds and dark attitudes: Lower cognitive ability predicts greater prejudice through right-wing ideology and low intergroup contact. Psychological Science 23, 187-195.
http://www.huffingtonpost.com.au/entry/intelligence-study-links-prejudice_n_1237796
http://www.livescience.com/18132-intelligence-social-conservatism-racism.html
http://sharpbrains.com/blog/2006/12/18/what-are-cognitive-abilities/