Paired associate learning: Data on pair difficulty and variables that influence difficulty

Two hundred pairs of five-letter words were produced randomly from all five-letter words in Thorndike and Lorge (1944). The difficulty of each pair was established for paired associate learning by having 50 subjects learn lists of 20 pairs. The difficulty of a pair was found to be highly reliable and was not influenced by the particular list in which it was learned. Frequency of response terms was positively related to learning, but the frequency of the stimulus terms was not. Two-syllable five-letter words were learned more rapidly than one-syllable five-letter words. Two 20-pair lists were constructed, one consisting of homogeneous pairs of average difficulty and the other of 10 very easy pairs and 10 very difficult pairs. As anticipated, performance on the latter list was initially better than that on the former, with the performance on the two lists converging over trials. The difficulty of the pairs as determined by paired associate learning was unrelated to misses on a recognition test, but the false alarms decreased as difficulty decreased.