Studies estimate that children between the ages of 6 and 11 spend on average 28 hours a week watching television and are exposed to as many as 20,000 commercials in a single year. With companies in the fast food industry right through to alcohol and drug industries all using television as an outlet for advertising, organizations are left to decide what is suitable for children to view and how children will react to the messages they receive through their advertisements. Since the 1970s there has been a large amount of concern as to whether or not children are able to comprehend advertisements and the extent to which they do so. A study conducted by Goldberg, M. E., & Gorn, G. J. in 1983 looked at the acquisition of children's cognitive defences and found that, until the age of 8 most children are unable to understand the selling intent of televised advertisements. Between the ages of 8 and 11 children only have a partial understanding of selling intent, and it is not until at least the age of 11 that a child is able to fully understand the selling intent of televised advertisements. The study concludes that there is a large difference in basic understanding of the purpose of advertising between children of a younger age and of an older age, and as a result different age groups have different reactions to televised advertisement.