The serial-position effect is the generalised psychological tendency people have to be able to recall the leading and trailing items in a list more easily than those towards the middle of the list.

It's very widespread and has been demonstrated and confirmed many times in different experiments (starting in 1913).

It has signiicant implications for those attempting to carry out a long list of tasks. It's also recently been found to be a crucial factor in complex website and other computer-based navigation tasks.

Many studies have attempted to find consistent reasons for the effect, but as yet none is generally accepted as a full explanation. See Wikipedia

Also see :Memoryplugin-autotooltip__plain plugin-autotooltip_bigMemory

inexplicable

"Although it is commonly accepted that learning and memory occur via enduring changes in neuronal properties such as synaptic strength within a network of neurons, many details of these processes remain unknown, including the mechanisms responsible for the persistence and maintenance of memory over long periods of time.