Capacity increase and chunking in the development of short-term memory

Together the two experiments show that an important part of short-term memory development can be explained as a growth inShort-term store capacity.

Abstract

The possibility of an age-related increase in the capacity of the short-term store was examined in two short-term memory experiments, and an M-operator model was proposed to account for the data. In the first experiment, lists of 8, 10, and 12 consonants were presented to 10-, 12-, and 14-year-olds. Despite the fact that the amount of chunking was monitored and kept constant across ages, there was a definite developmental increase in short-term memory performance. The size of the increase corresponded to the prediction of Pascual-Leone's M-operator theory. An M-operator model was proposed to account for the relation between performance level and list length at each age, as well as the developmental increase. Predictions of adult performance were tested in a second experiment. Together the two experiments show that an important part of short-term memory development can be explained as a growth in short-term store capacity.