Complex sentence: However, the age of 12 is commonly used as a cut-off point, on the basis of the widespread academic view that by age 12 children have developed their behaviour as consumers, effectively recognise advertising and are able to adopt critical attitudes towards it.
Split into simpler sentences: However, the age of 12 is commonly used as a cut-off point. This cut off point is on the basis of the widespread academic view that by age 12 children have developed their behaviour as consumers, can effectively recognise advertising and are able to adopt critical attitudes towards it.