Efficiency of the Add-A-Pair Method in Learning Paired-Associates

An unrecognized implication of Rock's (1957) analysis of paired-associate learning is that a most efficient way of learning a list is to begin with a single pair and add a pair each trial until the whole list is learned. A list of 17 difficult, single-lettered, 2-digit number pairs was used. 18 control Ss received all pairs for 9 trials, while 18 experimental Ss used the add-a-pair method. By the last trial and 153 exposures each, experimental Ss knew 9.72 pairs compared to 6.78 for controls, a significant advantage.