Why we are built to be forgetful

It is not necessarily a sign of mental impairment.

- Sven Vanneste and Elva Arulchelvan

Forgetting is part of our daily lives. You may walk into a room only to forget why you went in there - or perhaps someone says hi on the street, and you can't remember their name.

But why do we forget things? Is it simply a sign of memory impairment, or are there benefits?

One of the earliest findings in this area highlighted that forgetting can occur simply because the average person's memories fade away. This comes from 19th-century German psychologist Hermann Ebbinghaus, whose "forgetting curve" showed how most people forget the details of new information quite rapidly, but this tapers off over time. More recently, this has been replicated by neuroscientists.

Forgetting can also serve functional purposes, however. Our brains are bombarded with information constantly. If we were to remember every detail, it would become increasingly difficult to retain the important information.

One of the ways that we avoid this is by not paying sufficient attention in the first place. Nobel Prize winner Eric Kandel, and a host of subsequent research, suggest that memories are formed when the connections (synapses) between the cells in the brain (the neurons) are strengthened.

Paying attention to something can strengthen those connections and sustain that memory. This same mechanism enables us to forget all the irrelevant details that we encounter each day. So although people show increased signs of being distracted as they age, and memory-related disorders such as Alzheimer's disease are associated with attention impairments, we all need to be able to forget all the unimportant details in order to create memories.