Our beliefs are very powerful. Back in the 1940’s, a series of scientific experiments were carried out which revealed that if a healthy person was told they had a particular type of motor disorder and what symptoms they might expect to have, this information activated the same areas of the brain and triggered the same physical symptoms as the people who really did have the motor disorder. The research was generalised to many other areas and showed just how susceptible to suggestion human beings are. But it's dependent on where or from whom we receive the information. If a message is repeated enough times, this increases the likelihood of belief.
It was a fascinating finding and one which gave rise to the systematic and formal study of brain mechanisms involved in information processing, i.e. how systems, including human brains could be manipulated and controlled through the information they are fed, and how this can influence beliefs and behaviour. It's no coincidence then that this is referred to as 'Information Control Theory’ or ‘Cybernetics’.
But this is not the only research that's been done, this suggestibility also accounts for the Placebo effect, i.e. why someone can respond to medication when there is no active ingredient. And for the iatrogenic effect which refers to expectations according to what a person is told by a figure in authority, such as a doctor. In the neuropsychological world this is referred to as 'expectation as aetiology', i.e. what we expect influences outcome.
This has important implications for everyday life, if you think about it. We are very likely to be influenced day in day out by a multitude of different sources: what we read in the press, in social media, on the internet, on the news, what children are taught in school, what we hear and so on. Even just a fleeting glance at a newspaper headline can cause us to think about something in a particular way.
So be discerning and consider carefully what you choose to read, watch and believe.