The Availability Heuristic
Many of us tend to make decisions based on the first piece of evidence we encounter, or on information we can easily recall. The availability heuristic relies on the false premise that if something is new, or easily recalled, it must be important.
We estimate the likelihood of outcomes based on first examples that come to mind. We often weigh these examples as more important than alternative solutions that aren’t easily recalled. We bias our actions towards the most recent information, making new opinions, or worse — investment decisions, based on the latest news.
The more accessible something is in our memory, the higher probability we assign to it. For example: shark attacks and aviation fatalities. This is because examples of each are easily recalled and we tend to over estimate the probabilities of those events occurring.