As human beings, we live in the present. We also spend a lot of time looking forward to the future. But our thoughts and actions are often influenced more by the past. In many ways, who we are stems from where we've been and what we've done. The snapshots of the important events from our past make up our memory, and that memory guides our future in many ways.
But what exactly is memory? Although we speak of memory as if it were a physical organ, like our brain or spleen, it's not a physical object that exists within our body. Instead, it's an ongoing process that involves many parts of our bodies, especially our brains.
Memories are mental records of past events. As such, they consist of recollections of our personal experiences. Memory begins with the senses, since that's how we experience the world. If you think about it, your memories consist of remembrances of things you've sensed in the form of touches, tastes, sounds, sights, and smells.
As you experience the world around you, your brain decides which information needs to be saved. If you remembered everything you sensed every moment of the day, your brain would soon be so overloaded that you wouldn't be able to function.
Instead of remembering every little thing, your brain picks and chooses what's important. This is the information that forms your memories. The main part of your brain that does the work of processing memories is called the hippocampus. Scientists believe the memories formed by the hippocampus get stored in various areas of the cerebral cortex, which is the large outer area of the brain more commonly known as “gray matter."
When your brain stores a memory, it makes another decision about how important that memory is. The brain constantly filters and prioritizes information to avoid becoming overloaded with unnecessary or unimportant information.
Memories that only need to be retained for a brief time are put into short-term memory. For example, you might need to remember a phone number only long enough to dial the number or to save it in your phone.
Short-term memory has a very limited capacity. Scientists believe most people can retain information about roughly seven things for no more than 20-30 seconds in short-term memory. Of course, you can keep something in short-term memory by repeating it to yourself in order to keep resetting the clock for the short-term memory of that item.
The most important information eventually makes its way from short-term memory to long-term memory. This transition can take place because of the inherent importance of the information or as a result of repeated use or intentional repetition.
Fortunately, long-term memory does not have the same limits that short-term memory does. The human brain appears to be able to hold an unlimited number of long-term memories for an indefinite amount of time. If you think about it, you'll realize that some of your most precious memories are from years and years ago!