Humans have two types of memory
- Short-term memory
- Long-term memory.
Short-term memory is designed to remember things from a few seconds up to a few days. For example imagine going into a shop to buy a chicken sandwich, a green apple and a bottle sparkling water and your favourite magazine. How do most people remember this short list? Most people do so by rehearsing this to themselves i.e. saying the list in their heads over and over again.
One week later, many people will have forgotten what they bought in the shop. One month later, most people will have forgotten completely. So how does the brain decide to delete this information? What simply happens is the brain puts this information into short-term auditory memory and then it gets replaced by new information.
Short-term auditory memory resembles a cassette
What happens when the tape is full and you to record onto it again? You must go back to the beginning of the tape and record back over the old information which gets erased.
This is exactly how short-term memory works – new information constantly replaces old information.