How Things Work: Memory

Credit: Michael Setzer/SciTech Editor Credit: Michael Setzer/SciTech Editor Credit: Michael Setzer/SciTech Editor Credit: Michael Setzer/SciTech Editor

Whether studying for an upcoming exam, following a daily routine, or merely recognizing day-to-day objects, everyone is dependent on their memory to complete even the simplest tasks. Despite the fact that memory is such an integral part of our lives, scientists are only just beginning to understand the complex science behind our ability to remember.

The concept of memory can be generally broken up into three main categories: encoding, storage, and retrieval. Encoding deals with converting perceptions into chemical signals; this begins with our senses. According to, as our senses take in a variety of stimuli, the hippocampus and the frontal cortex — two parts of the brain — decide if the information is important enough to be remembered. If the information is deemed worthy, it is converted into chemical signals that travel through nerve cells in our brains.

The main action of encoding, however, occurs at synapses, which are the spaces in between nerve cells. When chemical signals reach a synapse, they fire across the gap to the next nerve cell, which releases neurotransmitters that create a link between the two cells.

As information is processed in this manner, a network of links between nerve cells is created throughout the brain. This process records all sensory perceptions including (but not limited to) visual, tactile, and emotional stimuli. The network constantly changes as more stimuli are encoded and is strengthened through repetition.

The second major aspect of memory, storage, is divided into sensory storage, short-term storage, and long-term storage. Sensory storage is used only for the initial perception of stimuli. Once the brain has decided that the information is worthy of being remembered, it is sent to either short-term or long-term storage. According to USA Today, short-term memory storage can hold approximately seven items for about 30 seconds. Anything past that is sent into long-term storage, where practically unlimited amounts of information can be stored indefinitely.

New stimuli are often linked with previous signals that are kept in long-term storage, which explains why it is often easier for people to remember things that are related to prior knowledge. A simple example of this is the use of mnemonic devices. By relating new information to something that the brain is already familiar with — such as the alphabet — the brain is forced to use neuron paths that have already been solidified by repetition. It then becomes much easier to remember new information.

The final category is memory retrieval. In order to remember something, the encoded information is unconsciously retrieved from the network of neurons present in the brain.

Difficulty in remembering something can be caused by a defect in any one of the three areas of memory. The stimuli might have never been properly encoded. The brain could have failed to store the information due to distractions or a glitch in short-term or long-term memory — or there could be a problem with the retrieval of the information. This last problem generally occurs when there is a discrepancy between the prompt the brain is using to remember the signal and the original signal that was encoded, according to

Through encoding, storage, and retrieval, humans are able to recognize everything from the time of day to complex mathematics. This allows people to perceive, understand, and respond to the variety of stimuli we encounter every day.