Describe the hierarchical organisation in long-term memory?

The hierarchical organisation in long term memory was suggested by Allan Collins and Roses Quillian. They observed that the knowledge in long-term memory is organised hierarchically in a networked structure.

The elements of this structure are concepts known as nodes. The connections between nodes are called labelled relationships that indicate category membership or concept attributes.

According to this view, all the knowledge can be stored at a certain level, which applies to all the members of a category without repeating that information at the lower levels in the hierarchy. It ensures efficient use of long-term memory through cognitive economy.