4 Amazing Facts About Memory
A lifetime of experiences, cataloged and stored in our brain, helps form internal biographies that orient us throughout our lives
The human brain’s memory capacity in the average adult can store trillions of bytes of information. In a Stanford Study, it was reported that the cerebral cortex alone has 125 trillion synapses.
In another study, it was reported that 1 synapse can store 4.7 bits of information. Neurons are the cells that process and transmit messages within the brain, and synapses are the bridges between neurons that carry the transmitted messages. Running the numbers — 125 trillion synapses — 4.7 bits/synapse, and about 1 trillion bytes equaling 1 TB (Terabyte).
1. The Brain Can Store 2.5 Petabytes of Information
According to a 2010 article in Scientific American, the memory capacity of the human brain was reported to be the equivalent of 2.5 petabytes of memory capacity. As a number, a “petabyte” means 1024 terabytes or a million gigabytes, so the average adult human brain can store the equivalent of 2.5 million gigabytes of digital memory.
To put that in perspective, according to Computerworld, Yahoo — the Internet giant — has created a specially-built 2.0 petabyte “data warehouse”. Yahoo uses the immense information storage capacity of this data warehouse to analyze the behavior of its half-a-billion monthly visitors. “It is not only the world’s single-largest database but also the busiest”, the magazine reported.
2. Dreaming Is the Result of the Brain Organizing Memories
Your brain sorts prioritizes and declutters memories while you sleep. The theory is that dreams help organize information acquired during the day as your brain decides whether each experience is a memory to keep or let fade away.
Research shows that during REM sleep, dreams are a reflection of a biological process wherein the brain strengthens neural connections to important experienced events while ditching the inessential information — all while preserving the integrity of current memories and adding new information.
You can kind of think of your brain as a very large filing cabinet, and every night, your brain has to add new files to its ever-growing record system while simultaneously not upsetting its organized methodology.
3. There Are Many Types of Memories
For years, researchers and experts have debated the classification of memories. Many experts agree that there are four main categories of memory. All other types of memory tend to fall under these four major categories.
Sensory memory allows you to remember sensory information after the stimulation has ended. Researchers who classify memory more as stages than types believe that all other memories begin with the formation of sensory memories. Typically your sensory memory only holds onto information for brief periods. Remembering the sensation of a person’s touch or a sound you hear in passing is sensory memory.
When a sensory experience keeps recurring, and you start to attach other memories to it, the sensory experience stops living in your sensory memory. It might move to your short-term memory or more permanently to your long-term memory.
As the name implies, short-term memory allows you to recall specific information about anything for a brief period. Short-term memory is not as fleeting as sensory memory, but it’s also not as permanent as long-term memory. Short-term memory is also known as primary or active memory.
Working memory is a type of memory that involves the immediate and small amount of information that a person actively uses as they perform cognitive tasks.
While some experts view working memory as a fourth distinct type of memory, working memory can fall under the classification of short-term memory and, in many cases, is even used interchangeably.
We store a vast majority of our memories in our long-term memory. Any memory we can still recall after 30 seconds could be classified as long-term memory. These memories range in significance — from recalling the name of a friendly face at your favorite coffee shop to important bits of information like a close friend’s birthday or your home address.
Explicit long-term memories are memories we consciously and deliberately took time to form and recall. Explicit memory holds information such as your best friend’s birthday or your phone number. It often includes major milestones in your life, such as childhood events, graduation dates, or academic work you learned in school.
In general, explicit memories can be episodic or semantic.
- Episodic memories are formed from particular episodes in your life. Examples of episodic memory include the first time you rode a bike or your first day at school.
- Semantic memories are general facts and bits of information you absorbed over the years. For instance, when you recall a random fact while filling in a crossword puzzle, you pull it from your semantic memory.
4. Some People Can Recall Every Day of Their Lives
Those blessed with a good memory can still usually conjure only a fuzzy picture of the past, but for people with hyperthymesia. Also known as Highly Superior Autobiographical Memory (HSAM), hyperthymesia is an extremely rare condition that allows an individual to remember their lives intensely on a day-by-day basis.
In a famous 60 Minutes interview in 2010, one person with hyperthymesia described her exacting recall as effortless, saying, “It’s almost as automatic as if you say, ‘What is your name and where do you live?’” Name any date, and they’ll almost immediately tell you what day of the week it was and what they did that day.
But a superhuman memory means remembering things best left forgotten. The first person to ever be identified with this condition, Jill Price, has described the experience as haunting, telling the Seattle Post-Intelligencer in 2008, “I’ve been through hell in my life.”
As of 2021, only 60 or so people have been diagnosed with the condition, but their superhuman memories give scientists an unparalleled opportunity to study the still-unknown marvels of the human mind.
