A false memory is a memory that is mistaken, but the patterns of false memories can often be traced to mistakes made when other information was filed. For instance in the example below, if a test subject saw the words 'dream', 'bed', and 'snore', they might later falsely remember that they had seen the word 'sleep'. False memories happen to some people more than others, and they can be increased in times of information overload and emotional distress.
In children, false memory may also present as 'mishearing.' Kindergartners are more likely to have false memories with similar sounding words, and older children (and adults), with words that are related or associated.
False Memory in Children
fMRI and true and false memory