
According to the Broadbent model, information passes from the senses and is held for a few seconds in the short term memory store where it will rapidly fade unless the selective filter mechanism permits access to the single limited channel, thence to the higher centres concerned with long term memory and control of behaviour.
The short-term store which feeds information into the processing channel, via the filter mechanism, was demonstrated to have certain limitations, in that only a relatively small number of items could be held in the memory at a given time, and that attention to new inputs causes old activations to fade away. Even short lists will completely fade in as little as 18 seconds if the subject is prevented from repeating the list to himself (a process known as 'rehearsal').
Certain information perceived by the senses will not be remembered because the selective filter prevents it reaching higher levels of processing.