The sweet spotPosted: February 23, 2016
I am sitting in the airport at Sydney, waiting for my flight back to Geelong. I’ve just taken part in a panel review of my PhD progress and caught up with my supervisors. I also attended a fascinating talk and discussion led by Jan Plass who started his career in cognitive load theory and has now branched out into studying various aspects of adaptive learning.
It’s given me the opportunity to think about a few issues related to cognitive load theory (CLT). It has been bothering me for a while that there are certain contradictory views coming out of cognitive science that seem to be bound up with the issue of germane cognitive load. When CLT was first formulated, two types of working memory load were identified; the intrinsic load related to completing a problem or task and the extrinsic load that is not required for problem solving but that might be generated by distracting information, images and so on. Later, germane load was added.
Germane load is essentially the component of the working memory load that leads to learning. It is a problem for CLT because it makes the theory unfalsifiable: design an experiment that reduces cognitive load and leads to learning and we can say that we have reduced extrinsic load; design one that increases load and is effective and we can say that we have increased germane load. The reverse explanations can also apply; if the reduced load leads to less learning we can say that we eliminated germane load an so on. The results of any experiment can be explained and so CLT ceases to be a scientific theory because it ceases to make predictions that may be proved wrong.
Sweller’s solution is to not explain anything in terms of germane cognitive load. His view is that CLT is not a theory of everything. Even so, CLT provides useful results. Those of you who have been following my Twitter account will no doubt have already clicked on a link to this excellent piece by Sweller that was recently published and that gives an historical background to CLT theory before going on to explain all of the important findings in simple terms. Germane load is not mentioned.
But if CLT is not a theory of everything then what exactly is it a theory of? I am starting to think that CLT findings are best applied to domains with high intrinsic load; domains such as maths and physics problem solving and the more analytical aspects of the humanities. In such domains, it makes sense as an heuristic to generally try to reduce load. There is so much to pay attention to that we might seek to eliminate any extrinsic load for novice learners whilst also breaking the major tasks down into smaller components to be trained independently: We learn to factorise and solve quadratic equations in isolation before we learn to solve word problems that require the use of quadratic equations (and we learn our times tables before we learn to factorise quadratic equations).
And yet there are other areas where precisely the reverse effect is found. The generation effect is the phenomenon where learning is enhanced by students having to generate a piece of information for themselves rather than by simply reading that information. This increases working memory load. Perhaps it is desirable to make learning a little bit harder? Perhaps this makes it more memorable?
The apparent contradiction might be solved if we consider that worked examples seem to be better than problem solving for complex kinds of problems whereas the generation effect seems to work for tasks that involve memorising single words or sequences of words. Sweller would define this as a difference in ‘element interactivity’. In an algebra or physics problem, each move is dependent upon another; the fifth line depends upon the fourth and so on. The elements of the problem interact. However, words and names are discrete items and so the element interactivity is low, even if the words are complicated or technical.
If we have a model of learning that suggests that we must engage but not overload the working memory in order to optimise learning then the worked example effect can be explained due to the fact that it reduces load to manageable proportions. The generation effect occurs because it increases the load of a learning episode that would otherwise possess a very low intrinsic load. If you want students to learn names and dates then generation could be a good strategy.
Similarly, when we become more expert, a series of problem moves becomes ‘chunked’ together as a single item and so this also effectively reduces the element interactivity of a problem, explaining why experts benefit more from problem solving than from worked examples.
There is some experimental evidence for this idea and it’s similar to some of the recent findings regarding the testing effect. A paper by Chen, Kalyuga and Sweller presents a series of experiments that show a worked example effect for high element interactivity and a generation effect for low element interactivity.
This is now falsifiable, provided that we can all accept the concept of element interactivity. If so, a worked example effect for very low element interactivity or a generation effect for high element interactivity would disprove CLT.
Do we therefore need the notion of germane cognitive load at all? I’m not sure. We might be able to make do with something simpler: Fill the working memory without over-filling it. Hit the sweet spot. Vygotsky would approve.