It is a well-established finding in the memory literature, that recall performance is superior when repetitions are spaced rather than massed. Nevertheless, in the context of inductive learning, the benefits of the spacing effect are not yet strongly established. To date, the few studies that have investigated the spacing effect in inductive learning have produced mixed findings. In addition, these studies have used only a few types of stimuli (e.g., paintings, novel objects and bird families), and have left some questions unanswered about the influence of the spacing effect in long-term retention and the mechanisms contributing to such effects.The broad aim of my research is to examine the spacing effect in the inductive learning of categories. Specifically, I have explored some of the issues addressed in the literature relating to the spacing effect in induction. These include the generality of the spacing effect over textual materials, the critical factor for the spacing effect —interleaving or temporal spacing, the effect of spacing of exemplars on memory retention and the effect of the difficulty of discrimination of learning material on the presentation style (massed vs. spaced).
Chapter 1 provides an introduction and a literature review for the present thesis. It also discusses the problems to be addressed in the present research, the general aim, specific objectives, research questions and the significance of the research. Chapter 1 concludes with a presentation of the thesis outline.
Chapter 2 presents the first experiment in my research which was a replication of Kornell and Bjork’s (2008) experiment. Kornell and Bjork’s (2008) finding was the only evidence of the spacing effect in inductive learning that was available at the commencement of the present research, thus it was important to evaluate their findings to provide a foundation for the future work in my study. The results of Experiment 1 clearly replicated the findings from Kornell and Bjork , that is, that participants’ performance was better in spaced study than in massed study, and that the majority of the participants judged massing to be more effective than spacing in the post-experimental questionnaire, even though their performance showed the opposite.
Chapter 3 presents a paper published in Learning and Instruction which reported two experiments that investigated the effect of spacing on induction, using textual materials. Specifically, Experiment 1 used visually presented texts and Experiment 2 used aurally presented texts. The results of both experiments extended the generality of recently observed spacing benefits to texts and showed a similar pattern of participants’ judgement favouring massed presentation as was observed in the replication experiment reported in Chapter 2.
Chapter 4 presents a paper accepted by Memory and Cognition which reported two additional experiments conducted in the present research. Experiment 1 examined whether it is interleaving or temporal spacing that is critical to the spacing effect in the situation when the memory load is high and the results favoured interleaving. Experiment 2 examined the effect of the difficulty of the category discrimination on presentation style (massed vs spaced) in inductive learning, and the results demonstrated that spacing (i.e. interleaving of exemplars from different categories) is advantageous for low-discriminable categories, whereas massing is more effective for high-discriminable categories. In contrast to these performance measures, massing was judged by participants to be more effective than spacing under both discriminability conditions, even when performance for low-discriminable categories showed the opposite.
Chapter 5 presents a paper submitted to Applied Cognitive Psychology (under review) which reported the last two experiments of the present research. The purpose of these two experiments was to investigate whether or not the benefits of spacing vary with retention interval in inductive learning —induction was tested either shortly after the study phase (short-term retention) or after a week’s delay (long- term retention). Specifically, Experiment 1 used paintings and Experiment 2 used textual materials (i.e. visually presented texts). The results of both experiments showed that the benefits of spacing for induction were found in both retention conditions, although, contrary to their actual performance, massing was judged to be more effective than spacing by most groups. It is argued that the benefits of spacing found in the present study are due to the interleaving of exemplars from several categories rather than the spacing between exemplars from the same category.
Some possible explanations for the spacing effect are discussed in the ‘General Discussion’ section of several chapters (i.e., Chapters 2, 3, 4 and 5), examples of which are: the interaction between induction and discrimination, the attention factor (e.g., Deficient Processing Theory), the role of forgetting, the study-phase retrieval.
Chapter 6 provides a general discussion for the present research which includes the summary of empirical findings, implications of the findings for education, limitations of the present research and suggestions for future research. Chapter 6 concludes by highlighting the important contributions of my thesis.