deirdre is always complaining about aches and pains. she spends hours on the internet looking up her symptoms, which often change from one day to the next. she has been to multiple doctors and specialists, all of whom tell her that no medical condition can be found. when people including her doctors, try to provide possible explanations for her ailments, deirdre brushes their advice aside. however, when she finds information that is consistent with her aches and pains, she believes that she knows what's wrong. this example illustrates the concept of: