A Comparative Study of the Effects of Equal and Expanding Spacing Schedules on L2 Receptive and Productive Vocabulary Retrieval

Spaced repetition seems to play a significant role in the learning and retention of words in foreign language settings. This experimental study investigated the impact of expanding and equal spacing conditions on receptive and productive English vocabulary retrieval. The participants consisted of 63 pre-intermediate EFL learners in three intact classes randomly assigned to one control and two experimental groups. A Vocabulary Knowledge Scale (VKS) was used to select 20 unknown word pairs (each word and its synonym) for teaching purposes and check the effects of the treatments at the end of the study. The word pairs were later divided into two 10-item A and B sets because of the counterbalanced design of the study. The first experimental group studied set A under an equally spaced condition (2-2-2) and set B under an expanding spaced condition (0-1-5) with the same absolute spacing value. The second experimental group studied them in the reverse order, thus counterbalancing the effect of encounter order. The control group studied the target items under the no-spacing or massed condition (0-0-0). The statistical analyses of the three groups’ posttest scores indicated that all the three groups had improved their receptive and productive vocabulary retrieval. However, an equally spaced schedule had led to a significantly higher mean score only on the receptive items of the posttest and, therefore, better vocabulary retrieval. Therefore, it is suggested that EFL teachers consider spacing in general and the equal spacing condition in particular as important elements in facilitating both receptive and productive vocabulary learning.