The Roles of Encoding Variability and Reminding in the Spacing Effect

Abstract

The spacing effect is the robust finding that long-term memory performance is better when material has been studied under spaced versus massed (e.g., crammed) conditions. The current study investigated the extent to which two different mechanistic accounts (i.e., reminding with desirable difficulty and reminding with encoding variability) can adequately explain the spacing effect. Across two experiments, word pairs were presented two times separated by either zero, three or ten intervening pairs. Repetitions of each word pair were presented either in the same or in different contexts across presentations. The type of reminding was manipulated across experiments. In Experiment 1, participants were consciously reminded to mentally “look back” through the study list for repetitions of items by being asked if the currently presented item had been previously studied earlier in the list. In Experiment 2, reminding was automatic during encoding because participants were not asked to “look back” across the study list for repetitions of items. Results from Experiment 1 revealed that the response latency for reminding was not predictive of final test performance. Instead results were consistent with the assumptions of encoding variability in the massed and short spacing conditions, but not the long spacing condition. Results from Experiment 2 further supported the encoding variability account across all massed and spacing conditions. Together, results suggest a minimal role of desirable difficulty and a potential benefit of encoding variability that is qualified by reminding quality in terms of recollection and familiarity as a basis for reminding.