It seems I may have misunderstood interpolated testing in a recent blog post. I assumed, by definition, that interpolated testing meant that there was switching between new and old learning in the testing of learners (or quizzing). For example, a typical starter quiz where a teacher would ask questions on previous learning, whilst also assessing the learner understanding on the new.
This understanding was corrected (or confused further?) in a recent lecture on interpolated testing by Dr Philip Higham of the University of Southampton. The talk was fascinating and raised several more questions I wish to consider, particularly in relation to the conflict between desirable difficulties and cognitive load theory (more to follow on this).
The aptly titled ‘PowerPointless’ began with Philip espousing desirable difficulties and the “metacognitive illusions” that exist in learning – massed practice, fluency, lecturer style, testing is bad etc.
Philip then explained a series of experiments that he has been working on with a PhD student. Each of these investigating the impact of slide handouts during lectures. Six lab-based experiments were conducted and pre-recorded lectures given to various groups:
- Group A – The control group where learners were asked to observe the lecture without taking notes
- Group B – This group were provided with lecture slides and could annotate these as they wished
- Group C – This group took notes from the slide for themselves
- Group D – This group were asked to take notes as if they were for a friend (it was suggested that the notes would be clearer and better organised through doing this)
The various experiments changed variables such as speed of presentation, fluency of presentation and used various topics. Learners were tested immediately after each experiment and then sat a delayed test one week later.
Results consistently revealed that note taking (of any kind) was significantly better than not taking notes and using the slides provided for the lecture (Group A and B). This is significant for all teachers who provide a copy of slides to their learners. Think about how you can encourage learners to take their own notes during sessions – I wrote a blog about the Cornell method a few years back that may be of use for this.
The experiments progressed further, and Group E was added; these individuals were the ‘interpolated testing’ group. This group experienced the lecture in short intervals of around ten minutes before being asked to generate their notes in a retrieval type manner (this is what is referred to as interpolated testing – and the literature that I have read to date typically uses this approach. A short introduction to new learning immediately followed by a retrieval of this new learning). As a side note, is this not just part of what teachers do for formative assessment? (perhaps formative assessment is so effective due to the retrieval aspect rather than feedback?).
The results showed that the retrieval and generation of notes (Group E) had an improved impact on immediate and delayed (1 week) test results compared to other groups.
All groups were then provided with 8 weeks of revision time using the same lecture handouts containing all answers. Following this, they were tested on the material. Results showed no significant difference between those that took their own notes and those that did the interpolated testing. However, the results did show that the quantity of time that learners revised for during the 8 weeks, was significantly lower for those that did the interpolated test (Group E).
These findings are significant:
- Taking your own notes is highly effective for improving long term retention of information
- To reduce study time, learners are better off learning via interpolated testing
It is worth noting that much of the literature is positive (see Szpunar et al) on interpolating, specifically for improving long term retention and motivation of learners. The reasons suggested by Davis et al for interpolated testing not being as effective as first thought, is due to:
- The learners spending more time thinking about the prior learning and correcting this, over moving to the new learning
- The more times that there is switching between old and new learning, the more the task switching effect will occur, thus impeding the new learning
In spite of this, there is a suggestion that ‘test potentiated learning’ (recalling prior knowledge) is actually beneficial to learning and this supports the acquisition of new information. This obviously needs further study, but suggests that teachers need to be mindful of how often they are switching between the delivery of new learning and the retrieval of it during sessions.
*NB. These were some of my notes and inferences from the lecture. Data and information is my interpretation of that which was shared. A huge thanks to Dr Philip Higham for sharing this information and challenging my thinking.
I would like to explore my initial thoughts on interpolated testing a little further, as I expected a delayed retrieval, rather than retrieval immediately after encoding. This allows for greater forgetting which one would think is better… anyway, more thought needed on this.