An encoding failure in psychology refers to a situation in which information does not enter the brain's long-term memory. In these instances, the brain simply does not store all the information a person sees.
The brain is bombarded with information on a daily basis. A person can look at an object but not really process all the details concerning it. For instance, two people meet for the first time and have a brief conversation. If one of them is asked several hours later the color of the other person's eyes, he may not remember. An encoding failure, or failure to store the information, causes the person not to recall that detail. Encoding failures are just one reason for forgetting information.