Memory in children--Psychological aspects

The relationship between the mental effort requirement
of strategy use and the development of an organizational
strategy was investigated. 1st, 3rd, and 5th graders were
assigned to one of four conditions reflecting the orthogonal
combination of organizational instructions (training vs free
recall) and item presentation (blocked by categories vs
random). During two free recall trials of a list of 16
words, subjects' mental effort expenditure was assessed by
measuring interference on a secondary task (finger tapping).
The older children recalled more items and were more
strategic than the younger children; however, there were no
differences in interference among the grades. Training
resulted in superior recall, clustering, and mental effort
expenditure; blocked presentation led to greater recall and
clustering, but not interference. It was suggested that the
activation of items in semantic memory and the use of
categorical organization to facilitate recall become more
efficient with age, resulting in superior performance by the
older children without corresponding increases in mental
effort.