We gather and dispense information about our intimate environment through personal and electronic contact with family, friends, and associates. Mass media (MM) provide much of our knowledge of the larger environment. Last month's column focused on MM as a cultural phenomenon that we must understand if it's to inform but not unduly influence our cognitive processes. This column will focus on the techniques that (non-entertainment) MM use to shape and distort information and beliefs.

Mass media play an important role in democratic societies and competitive markets that function through the efficient persuasion of large widespread audiences. It's no surprise then that governments seek to control MM output, and that many who use MM distort the truth when seeking support for their cause. Websites have recently become an important, relatively inexpensive, unregulated venue for disseminating information, and so we should be as aware of who's running a website as we are of other MM venues we use, and also as leery of what's published on it.

Mass media have now evolved to the point where conflicting media messages constantly bombard us. How do we select what to attend to and what to believe?

Our brain must constantly differentiate between what's currently important (foreground) and peripheral (background or context). It does this through an attentional buffer (commonly called our working brain) that allows us to focus on only a few units of information for a short period of time while we determine their importance within the larger perceptual field.