The spacing effect in the learning of word pairs.

Following the presentation of a single list of word pairs consisting of a three-letter word on the left and a five-letter word on the right, groups of 64 Ss each were asked to recall the (a) three-letter words, (b) five-letter words, (c) intact pairs, or (d) five-letter words with the three-letter words provided. Two types of repeated pairs were presented, one in which the same three- and five-letter words were repeated together (same pairs) and one in which the same five-letter word was repeated with different three-letter words (different pairs). For half of the Ss in each recall group, the repetitions of a pair containing a given five-letter word were massed (MP); for the other half, the repetitions were distributed (DP). Recall of MP same pairs and the eomponents of these pairs was consistently poorer than that of DP same pairs. Recall of the repeated component of the different pairs was also poorer under MP than under DP. The results were interpreted as supportive of an attenuation-of-attention explanation of the spacing effect.