Visual short term memory is an area of memory that allows people to store visual information, usually for less than a minute, in case they need it for reference. Memories stored in this way are subject to rapid decay, and will quickly break down because the brain determines they are not necessary for long term use. The processes involved in encoding and storing memory are very different with short and long term memory, and the recall processes are also distinct.
In humans, visual short term memory tends to be limited in scope, with people storing between three and seven pieces of visual information in their short term memory. This allows people to do things like remembering facial expressions to register visual changes, or remembering a color for reference on an examination. If memories are actively used, they move into working memory for the brain to view, and otherwise they break down and become unrecallable.
Information stored in visual short term memory is readily accessible through rapid recall if it is needed, but does not endure. This can be an issue with situations like interviewing criminal witnesses. People who see a crime may think they are reliable sources of information, especially if it just happened, but their memories can be faulty; a blue car may turn into a red car in recall, for example, or the perpetrator’s physical characteristics may not be accurately recalled.
Short term memory in general appears to rely on more verbal than visual cues. It is much easier for people to remember larger chunks of verbal information, like a list of numbers, than it is to track visual information. Visual short term memory can provide useful rough references, but it can also be surprisingly unobservant. For example, many people demonstrate a phenomenon known as change blindness, where they fail to notice significant environmental changes until the changes flip back and forth multiple times.
Research on visual short term memory explores the ways in which people encode and retrieve this information, and what happens when it goes wrong. People with brain injuries and degenerative neurological diseases, for example, may have trouble forming short term memories. This can make it difficult for them to engage in daily activities, even if they have perfect long term memory recall for events that happened in the past. Understanding how and why the brain forms memories can help researchers develop new approaches to the treatment of memory loss and related disorders.