Impact of reducing intrinsic cognitive load on learning in a mathematical domain
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Transcript of Impact of reducing intrinsic cognitive load on learning in a mathematical domain
Impact of Reducing Intrinsic Cognitive Load on Learningin a Mathematical Domain
PAUL AYRES*
School of Education, University of New South Wales, Sydney, Australia
SUMMARY
This paper examines the effectiveness of instructional strategies that lower cognitive load by reducingtask complexity (intrinsic cognitive load). Three groups of 13-year-old students were required to learnamathematical task under different conditions. One group (Isolated) followed a strategy that used part-tasks where the constituent elements were isolated from each other (element isolation). A secondgroup (Integrated) received whole tasks where all elements were fully integrated, and a third group(Mixed) followed a mixed strategy progressing from part-tasks to whole-tasks. Results indicated thatthe part-task strategy was effective in lowering cognitive load for all students, but only benefittedlearning for students with low prior knowledge. In contrast, students with a higher prior knowledgelearned significantly more having studied whole tasks during instruction compared with part-tasks.The mixed-mode method proved to be ineffective for both levels of prior knowledge. These results arediscussed in terms of cognitive load theory. Copyright # 2006 John Wiley & Sons, Ltd.
How can we make complex tasks easier to learn? Recent advances in cognitive load theory
(CLT) may provide some clues. A key tenet of CLT is that overloading working memory
inhibits learning and therefore in order to facilitate learning, cognitive load (working
memory load) must be kept at a manageable level. The main aim of this study was to
investigate the impact of lowering cognitive load by directly reducing problem complexity
(intrinsic cognitive load).
CLT researchers have identified three sources of cognitive load that occur during
learning: Intrinsic, extraneous and germane. Intrinsic cognitive load is the load placed on
working memory by the intrinsic nature of the materials to be learned. Extraneous
cognitive load is created by the instructional mode and conditions, while germane
cognitive load is the load required for schema formation and automation (see Paas, Renkl,
& Sweller, 2003; Sweller, van Merrienboer, & Paas, 1998). Whereas germane cognitive
load has a positive influence as working memory resources are directly engaged in
learning, the other two forms of cognitive load can have a negative effect. If either intrinsic
and/ or extraneous load is high then working memory can become overloaded and
adversely affect learning.
APPLIED COGNITIVE PSYCHOLOGYAppl. Cognit. Psychol. 20: 287–298 (2006)
Published online in Wiley InterScience(www.interscience.wiley.com). DOI: 10.1002/acp.1245
*Correspondence to: P. Ayres, School of Education, University of New South Wales, Sydney NSW 2052,Australia. E-mail: [email protected].
Contract/grant sponsor: Faculty of Arts and Social Sciences at the University of New South Wales, SydneyAustralia.
Copyright # 2006 John Wiley & Sons, Ltd.
It is argued that the three sources of cognitive load are additive (see Sweller, in press) and
the total cognitive load is given by the sum of the three. If intrinsic load and/or extraneous
load is reduced then there is the potential to increase germane load without overloading
working memory. From this perspective, instructional designers have a potential incentive
to lower either or both of these two loads. Whereas strategies to lower extraneous load are
well documented (see Sweller, 1999; van Merrienboer & Ayres, 2005), methods to lower
intrinsic load have only more recently been investigated. The present study continues this
recent research trend by testing the effectiveness of a strategy (element isolation) to lower
intrinsic cognitive load and facilitate learning in a mathematical domain (algebra).
INTRINSIC COGNITIVE LOAD
This section examines intrinsic cognitive load in more detail and discusses some of the
strategies researchers have employed to reduce it.
Element interactivity
It is argued that element interactivity is the main generator of intrinsic cognitive load (Paas
et al., 2003; Sweller & Chandler, 1994). Element interactivity refers to the way the
individual elements of a task interact with other. Tasks low in element interactivity contain
elements that do not react with each other, can be learnt in isolation, and require relatively
low working memory load. In contrast, tasks high in element interactivity contain
interacting elements that cannot be learnt in isolation, and therefore require a higher
working memory load. Consequently a task is difficult to learn because of the number of
elements that have to be assimilated simultaneously rather than the number of elements the
task contains (Sweller, 1999; Sweller & Chandler, 1994). Element interactivity is innate to
a task, dependent only upon the number of interacting elements present, and cannot be
manipulated by instructional design without changing the nature of the task or
compromising understanding (see Chandler & Sweller, 1996; Paas et al., 2003; Pollock,
Chandler, & Sweller, 2002). However, as expertise develops in a domain, the intrinsic load
caused by a specific task decreases as the interactions become learned and incorporated
into schemas (Kalyuga, Ayres, Chandler, & Sweller, 2003; Renkl & Atkinson, 2003). By
possessing domain-specific schemas, the learner is able to treat interacting elements as
single elements (chunks), thus reducing intrinsic cognitive load.
Lowering intrinsic load through instructional design
Researchers have often used the principle of schema acquisition in their strategies to reduce
intrinsic cognitive load. One method is pre-training (see Mayer & Moreno, 2003), where
learners initially develop specific prior knowledge before the final materials are presented.
For example, Mayer, Mathias, and Wetzell (2002), using a multimedia environment, found
that learning was enhanced when learners received an initial pre-training phase on
individual components of a mechanical system, before learning about the full causal model
(all components together). Similarly, Clarke, Ayres, and Sweller (2005) found that
spreadsheet novices benefited from pre-training in spreadsheet skills before using them to
learn mathematical concepts. In contrast, learning was not as effective with an integrated
approach that required both mathematical concepts and spreadsheet skills to be learned
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
288 P. Ayres
simultaneously. Simple-to-complex sequencing has also been recommended as an
effective strategy to reduce intrinsic cognitive load (see also van Merrienboer, Kester, &
Paas, 2006). In particular, the initial presentation of part-tasks helps consolidate procedures
or rules, which can be applied to whole tasks at a later stage (van Merrienboer, Clark, & de
Croock, 2002). Other similar techniques, such as focusing on subgoals (Catrambone, 1998)
or segmenting materials (Mayer & Chandler, 2001) before the full tasks are presented, have
also been found to be effective.
The strategies outlined above rely on a sequential approach to lower intrinsic cognitive
load. As Gerjets, Scheiter, and Catrambone (2004) observe, such approaches do not change
the intrinsic load of the tasks directly, but change the tasks themselves in the initial
instructional phase. Furthermore, vanMerrienboer, Kirschner, and Kester (2003) argue that
a part-task approach may not be that effective for complex learning environments that
require the integration of a number of skills, knowledge and attitudes. In such
circumstances, it is proposed that whole tasks should be presented initially, although in a
more simplified (reduced intrinsic load) format before progressing to full complexity.
Using whole tasks and directly reducing intrinsic load is a strategy also proposed by Gerjets
et al. (2004) who argue the case for a modular approach. In a modular approach solution
procedures are subdivided into smaller meaningful units.
A further study by Pollock, Chandler, and Sweller (2002) combined both a sequential
approach with a strategy to directly reduce intrinsic cognitive load. A notable feature of the
Pollock et al. design was to deliberately reduce element interactivity, rather than merely
create simpler part-tasks. Pollock et al. argued that novices, with little schema acquisition
in the domain, find learning new complex skills difficult because of high element
interactivity. As a solution to this problem Pollock et al. proposed a two stage learning
experience for novices. The first phase requires the tasks to be de-constructed in such a way
as to reduce the simultaneous processing of elements. During this phase learning is
conducted element-by-element, which reduces working memory load, and allows some
partial schemas to be acquired but with reduced understanding. In the second phase the
integrated tasks are introduced; and, with the aid of partial schemas, learners have an
increased working memory capacity to cope with the interacting elements. This strategy
was called the isolated-elements procedure and in two experiments (1 and 3), Pollock et al.
demonstrated that novices did indeed learn more (about electronics) using this technique
than learners who received an equivalent two-stage approach with materials consisting of
only fully integrated elements. Furthermore, it was also found (experiments 2 and 4) that
learners with more knowledge in the domain did not benefit from an isolated-elements
approach compared with a fully integrated approach because of prior knowledge.
AIMS OF THE STUDY
Amain of this study was to extend the research on the isolated- elements strategy and to test
its effectiveness in a mathematical domain. Although Pollock et al. (2002) found different
effects according to the knowledge base of the learners these differences were not directly
compared. Previous CLT research has identified the expertise reversal effect (see Kalyuga,
Ayres, Chandler, & Sweller, 2003, for a review) as a major phenomenon in instructional
design: Instructional strategies that are effective for novices may be ineffective for more-
expert learners. Consequently, the influence of expertise was an additional focus in this
study.
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
Impact of reducing intrinsic cognitive load 289
Algebraic tasks of the type 5(3x� 4)� 2(4x� 7), where students are required to
multiply out the brackets, were chosen as the mathematical learning domain for two
reasons. Firstly, the types of errors made and their causes have been mapped previously by
Ayres (2001, in press) and are not considered an easy task for many school-aged children.
In particular, students often make errors due to high working memory loads, rather than
through lack of knowledge. Secondly they are a very suitable medium to isolate elements
and reduce interactivity. To complete bracket expansion tasks (described in more detail
later in the paper) four successive calculations need to be made. However, when learners
are presented with the whole task, learners need to decide which terms and operators
(elements) need to be combined to identify the four calculations. Consequently, these tasks,
like many tasks in mathematics (Sweller & Chandler, 1994) are high in element
interactivity because of the total number of combinations (interactions) that need to be
considered simultaneously. However, if the learner is guided to focus on individual
calculations rather than the whole task, the number of combining elements is reduced
significantly. Thus an isolated-elements strategy was achieved in this study by requiring
students to learn and practice calculations individually, rather than as a sequence of
interacting calculations.
EXPERIMENT 1
In this experiment the effectiveness of the proposed isolated-elements strategy was
evaluated. Two sets of bracket tasks were devised. One set (Integrated) required all four
calculations to be completed per problem, whereas the second set (Isolated) required only a
single calculation to be made (isolated-elements). However, the second set was designed in
such a way that it was equivalent to the first set, requiring identical calculations to be made
overall. It was expected that the isolated set of problems would be easier to solve than the
integrated set because element interactivity was significantly reduced in the former. To test
this hypothesis, errors rates and self-rating measures of cognitive load were directly
compared on both sets of problems.
Method
Participants and design
Thirty-four eighth grade girls (mean age of 13.8 years) of average mathematical ability
from a Sydney Girls high school were assigned at random to either a group receiving the
isolated set of problems (the Isolated group, N¼ 17) or the integrated set (the Integrated
group, N¼ 17). All students had received some experience on the given tasks as part of
their normal school curriculum prior to completing this experiment.
Materials
A booklet was designed for each group (Isolated and Integrated), containing worked
examples, test problems and a subjective rating task of cognitive load. The booklets
consisted of A4 sheets of paper with sufficient space for students to write their answers. For
the test phase, a problem set of eight bracket problems, as described above, was created. In
the Integrated booklet, the eight problems were presented as whole tasks, with each
problem requiring four separate calculations to be made. In the Isolated Booklet, the same
eight problems were presented but repeated in groups of four, with each problem requiring
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
290 P. Ayres
exactly one calculation. The required calculation was indicated by an arrow, which was
drawn under the relevant within-bracket term (see Appendix A for examples). To ensure an
equivalence of materials, all problems in the Isolated set required single calculations,
which exactly matched the four calculations (including position) of an equivalent bracket
problem in the Integrated set. For example the first four test problems (see Appendix A) in
the Isolated booklet required the calculation of �3�2x, �3�� 4, 9�4, and 9�� 2x,
respectively which matched the four calculations needed to expand the first test problem in
the Integrated booklet. This design was repeated for all eight original bracket problems.
Consequently problems in the Integrated set required a total of 32 calculations presented as
eight whole tasks, whereas problems in the Isolated set required the same 32 calculations
but presented in 32 part-tasks.
In order to ensure that the participants understood what was required and to provide a
limited review on the topic, as well as model solutions, both booklets contained worked-
examples. The Integrated booklet contained two fully worked-examples (four calculations
each), whereas the Isolated booklet contained the same two problems but desegregated into
eight matched partially worked-examples (single calculations each) as previously
described. Consequently, both groups received an equivalent introduction involving a total
of eight calculations. These worked examples were presented on the first pages of the
answer booklets. Appendix B illustrates a worked-example for each group.
To ascertain the cognitive load demands of the test problems, a self-rating scale of
mental effort was used (see Paas & vanMerrienboer, 1994; Paas, Tuovinen, Tabbers, & van
Gerven, 2003), consisting of a nine-point scale: 1 (extremely easy), 2 (very easy), 3 (easy),
4 (quite easy), 5 (neither easy or difficult), 6 (quite difficult), 7 (difficult), 8 (very difficult),
and 9 (extremely difficult). Each of these choices was presented in the answer booklets
immediately following the last test task.
Procedure
All students were given one of the two booklets at random in their regular mathematics
class at school. They were told to study the worked examples given, complete the problem
sets and rate how easy or difficult they found the test problems. All students were given
sufficient time to finish all tasks. All answers were written in the booklets and calculators
were not used.
Results and discussion
The self-rating measure and the number of errors made by each student on the test
problems were recorded. The Isolated group had a mean error rate of 1.0 (SD¼ 1.7) and
mean cognitive load rating of 2.5 (SD¼ 1.3); whereas the Integrated group had a mean
error rate of 2.8 (SD¼ 2.9) and mean cognitive load rating of 3.6 (SD¼ 1.7). It was notable
that all students in the Isolated group completed individual calculations as indicated by the
arrows. No misinterpretations were evident, indicating that the arrow strategy was
effective. Two-tailed t-tests revealed significant differences for errors, t (32)¼ 2.16,
p< 0.05, Cohen’s d¼ 0.8, and cognitive load, t (32)¼ 2.11, p< 0.05, d¼ 0.7. Both these
results, with medium to large effect sizes, are consistent with each other–the group that
received the brackets in the form requiring single calculations, made fewer errors and rated
the task easier than students who received the brackets in the traditional format. These
results support the prediction that a single-calculation strategy (isolated-elements) reduces
element interactivity and consequently overall cognitive load in this domain. It should be
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
Impact of reducing intrinsic cognitive load 291
noted that a Cohen’s d effect size is used throughout this paper, where 0.2. 0.5 and 0.8
represent low, medium and large effects, respectively (see Cohen, 1988).
EXPERIMENT 2
The results of Experiment 1 indicated that an isolated-elements strategy reduces both the
error rate and cognitive load in this domain. In this experiment, the effectiveness of
isolated-elements as an instructional strategy was examined. Three strategies were directly
compared. The first strategy (Integrated) was based on whole problem instruction,
consistent with the traditional teaching approach in this domain. The second strategy
(Isolated) consisted of an instructional format based on individual calculations (isolated-
elements). The third strategy (Mixed), based on the principles of a sequential strategy (see
Mayer & Chandler, 2001; Mayer et al., 2002; Pollock et al., 2002), combined the previous
two strategies by switching from an isolated to an integrated mode. All three strategies
utilised worked examples (see Atkinson, Derry, Renkl, & Wortham, 2000, for a summary)
to keep additional extraneous cognitive load to a minimum. It was hypothesised that if
learners, particularly those with little expertise in the domain, were presented instructional
materials in an isolated-elements format, learning would be enhanced as a result of reduced
intrinsic cognitive load. However, it was also predicted that learners with expertise in the
domain would be able to learn without a reduction in intrinsic load. To test these
predictions, a measure of the learner’s mathematical ability was collected.
Method
Participants and design
The participants were 78 eighth grade girls (mean age of 13.1 years) from a Sydney Girls
high school. School-based assessments in the form of end-of-year examinations of general
mathematical ability including algebra were used to rank the students as either at or above
the median level, or below the median for this school grade. Two groups of differing
mathematical ability were therefore identified and classified as above average (N¼ 41) or
below average (N¼ 37). It should be noted that the ‘above’ and ‘below’ ability labels used
throughout this paper represent only relative differences of the cohort. These students were
randomly assigned to either the Isolated (Above N¼ 14, Below N¼ 12), Mixed (Above
N¼ 13, Below N¼ 13) or Integrated (Above N¼ 14, Below N ¼11) groups.
Materials
Two booklets were designed for each group corresponding to an acquisition and learning
phase. The booklets consisted of A4 sheets of paper with sufficient space for students to
write their answers. For the acquisition phase, four pairs of bracket problems similar to
those used in Experiment 1 were created as a basis for all three instructional strategies. The
first problem in each pair was designed as a worked example to study while the second
problem had to be solved. For example, the worked solution to �3 (2x� 4)þ 9 (4� 2x)
would be given (see Appendix B) and then a problem with similar features, such as �5
(3x� 6)þ 7 (2� 8x), was presented as a problem to be solved. In the Integrated booklet all
problems were presented as whole tasks, requiring learners to study four worked-solutions
and solve four problems requiring a total of 16 calculations to be made. In contrast,
problems in the Isolated booklet were presented as part-tasks, desegregated from the full
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
292 P. Ayres
tasks, as previously described in Experiment 1, with arrows identifying specific
calculations. As a result of this design, 16 (part-task) problem pairs were presented in the
Isolated booklet, corresponding to the same four problem pairs in the Integrated booklet. In
the Mixed booklet, the acquisition phase consisted of the first eight problem pairs (part-
tasks) presented in the Isolated booklet, followed by the last two problem pairs (whole-
tasks) presented in the Integrated booklet. The same 16 calculations were required as in the
other two booklets. To assess cognitive load during instruction, the subjective instrument
used in Experiment 1 was again employed. This task was presented immediately following
the acquisition phase in each booklet.
For the test phase, an identical test booklet was constructed for all three groups. These
booklets contained eight problems consisting of bracket expansion tasks similar to those
studied in the acquisition phase. All problems were presented in a fully integrated (whole-
task) format requiring the four calculations to be made. To ensure that the task was
understood, a worked practice example was positioned on the first page before the problem
set was commenced. This was particularly important for the Isolated group who had not
experienced such a task in their acquisition period.
Procedure
The acquisition and test phases were administered on consecutive days during the students’
normal mathematics classes at school. Calculators were not used and sufficient time was
given for all students to complete both phases. No feedback was given and students did not
have access to their acquisition booklets while completing the test phase.
Results
In both phases the errors made by each student were recorded. For each of the six groups,
means and standard deviations of errors made and cognitive load scores are reported in
Table 1. For the test phase 3 students were absent from school and did not participate,
adjusting numbers in each group to: Isolated (Above N¼ 14, Below N¼ 13), Mixed
(Above N¼ 12, Below N¼ 12) or Integrated (Above N¼ 13, Below N¼ 11).
Acquisition phase
A 3� 2 ANOVAwas conducted on the cognitive load measures and the errors made during
the acquisition period. For the self-rating measures there was a significant main effect for
Table 1. Mean (standard deviations) cognitive load measures and error scores for acquisition and testphases in Experiment 2
AbilityInstructional
methodCognitive
load measuresAcquisitionphase errors
Test phaseerrors
Above Average Isolated 2.29 (1.14) 0.86 (1.17) 4.57 (3.34)Mixed 3.46 (1.05) 1.31 (1.11) 3.42 (4.38)
Integrated 3.64 (1.45) 1.71 (1.59) 1.14 (1.70)Combined groups 3.54 (1.27) 1.29 (1.33) 3.03 (3.50)
Below average Isolated 3.54 (1.27) 1.17 (1.40) 3.22 (3.15)Mixed 3.71 (1.51) 2.75 (1.96) 5.25 (3.31)
Integrated 4.55 (1.04) 2.45 (1.57) 5.09 (3.53)Combined groups 3.91 (1.33) 2.11 (1.76) 4.58 (3.32)
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
Impact of reducing intrinsic cognitive load 293
instruction strategy, F(2, 70)¼ 5.59, MSE¼ 8.87, p< 0.01, d¼ 0.8. A post hoc Fisher’s
LSD test (used throughout the paper at the 0.05 level) revealed that students rated the
Isolated strategy significantly less demanding than either the Integrated or Mixed strategy.
There was also a significant main effect of ability, F(1, 70)¼ 7.64,MSE¼ 12.12, p< 0.01,
d¼ 0.6. Students with above average mathematical ability found the tasks required less
mental effort than below average students. There was no interaction between the two, F(2,
70)¼ 1.05, MSE¼ 1.66, p¼ 0.36. For the number of errors made there was a significant
main effect for instructional strategy, F(2, 70)¼ 4.22, MSE¼ 9.29, p< 0.05, d¼ 0.7. The
post hoc test revealed that students made significantly fewer errors using an Isolated
strategy compared with both the Integrated and Mixed strategies. There was a significant
main effect of ability, F(1, 70)¼ 5.91, MSE¼ 13.01, p< 0.05, d¼ 0.5, with higher ability
students making fewer errors. There was no significant interaction, F(2, 70)¼ 0.94,
MSE¼ 2.07, p¼ 0.40. Overall the results, with medium to large effect sizes, from the error
analysis matched the cognitive load ratings. Error rates and cognitive load levels were
lowest for the Isolated group.
Because it was predicted that the knowledge base of the learner would impact on the
effectiveness of the instructional mode, planned contrasts for both low and high ability
students were conducted on instructional strategy throughout this experiment. For students
with the lower ability there was no significant result for cognitive load, but a close to
significant result for acquisition errors, F(2,32)¼ 3.05,MSE¼ 8.45, p¼ 0.06, d¼ 0.8. The
post hoc test revealed that the Isolated group made significantly less errors than the Mixed
group. For the higher ability groups there was no significant difference for acquisition
errors, but a significant effect for cognitive load measures, F(2, 38)¼ 5.00, MSE¼ 7.54,
p¼ 0.01, d¼ 1.0. Post hoc comparisons revealed that the Isolated strategy was rated
significantly easier than both the Integrated and Mixed strategies.
Test phase
A 3� 2 ANOVA was conducted on the errors made during the test phase. A significant
result was found for ability, F(1, 66)¼ 3.53, MSE¼ 38.4, p¼ 0.06, d¼ 0.5, but no
significant main effect was found for instructional strategy F(2, 66)¼ 0.86, MSE¼ 9.24,
p¼ 0.43. However a significant strategy-ability interaction was found, F(2, 66)¼ 3.76,
MSE¼ 40.97, p< 0.05, d¼ 0.7 (see Figure 1). A simple main effects test revealed a
significant difference between the three strategies, F(2, 37)¼ 3.99,MSE¼ 42.46, p< 0.05,
d¼ 1.0, for the higher ability group, with the Integrated strategy superior to the Isolated
strategy under the post hoc test. No significant simple main effects were found for the lower
ability students.
GENERAL DISCUSSION
The interaction found on the test results in Experiment 2 is consistent with an expertise
reversal effect (Kalyuga et al., 2003). The effectiveness of the instructional strategy was
dependent upon the mathematical knowledge base of the learner. Clearly the higher ability
group performed better with a fully integrated strategy compared with an isolated-elements
approach. Although no significant differences for the lower ability group during the test
phase were found, the lowest error rates for both the test and acquisition phases, as well as
the lowest cognitive load rating were obtained by an isolated strategy. All of which support
the prediction that the isolated mode is more beneficial for the lower ability students.
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
294 P. Ayres
Of great theoretical interest were the overall results for the higher ability students.
Although tests results showed that the integrated-elements strategy was superior, during
acquisition the isolated strategy was rated the least cognitively demanding mode and the
least number of errors were made (see Table 1). This raises an interesting question—why
did a strategy that reduced cognitive load significantly and lowered error rates
appreciatively not transfer as well to learning? The answer may well lie with germane
cognitive load. The results suggest that germane cognitive load was also low for these
students in the isolated group otherwise more learning would have been expected. It is
therefore feasible that this particularly learning strategy failed to engage these students
sufficiently in the learning process—it was perhaps too simple. In such situations learners
may need to be engaged more directly in cognitive processing linked to schema
acquisition. In contrast for lower ability students, the reduction in intrinsic cognitive load
may have made it easier to understand the mathematical processes and invest more mental
effort in learning (germane cognitive load).
Previous explanations of the expertise reversal effect have pinpointed redundancy as the
main cause (see Kalyuga et al., 2003). However in this study, even though the isolated-
elements mode may have been redundant for the high knowledge students, any such
redundancy did not increase cognitive load. A lack of germane cognitive load is therefore a
more likely cause of the expertise reversal effect in this case, an explanation previously
promoted by Renkl and Atkinson (2003). Consequently an important conclusion follows
from this analysis—reducing cognitive load will not automatically facilitate learning if
germane load is also lowered.
Limitations and future directions
This study was limited to some degree by the small number of participants, the restricted
mathematical domain and some design features. Firstly the number of students in each
Figure 1. Strategy-ability interaction for errors made during the test phase of Experiment 2
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
Impact of reducing intrinsic cognitive load 295
treatment cell was quite small and consequently the study may have lacked power.
Nevertheless, all effect sizes for the main results connected to the effectiveness of
instructional strategies and the levels of cognitive load were generally quite large
(minimum d value of 0.7) and may compensate for the small n. Secondly, only 13 year-old
girls were included in the study. Although previous research in the domain by Ayres (2001)
found no gender differences, future research should include both, as well as larger cell sizes
and different age groups. One reason the domain was chosen was that the elements of
the tasks were easily isolated due to the sequential nature of the problems. However, these
tasks are somewhat limited mathematically. Consequently, in order to generalize the
findings further other mathematical domains need to be considered. Fourthly, no
instructional times were collected in the study as sufficient timewas allowed for students to
finish all tasks. Such a measure may have provided further insights into the instructional
modes in terms of efficiencies. Again future research might include this measure.
Lastly, it was surprising, considering the research support for a two-phase model (see
Mayer et al., 2002; Pollock et al., 2002; van Merrienboer et al., 2003) the mixed strategy
did not appear to be effective for either of the ability groupings. Whereas the higher ability
students could learn from the integrated mode alone and did not need a mixed strategy, the
lower ability students also did not benefit from a sequenced approach. It is not possible to
explain this latter result from the data collected, but it’s feasible that the lower ability
students may have needed a greater exposure to the isolated mode before switching. Future
research could investigate the conditions under which a two-phase model could be
effective.
ACKNOWLEDGEMENTS
This research was supported by a grant from the Faculty of Arts and Social Sciences at the
University of New South Wales, Sydney Australia. I also thank the reviewers.
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Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
Impact of reducing intrinsic cognitive load 297
APPENDIX A
APPENDIX B
Examples of test problems per group given in Experiment 1
Test problem for the integrated group Test problems for the isolated group
For each problem expand the bracketsQ.1 �3 (2x� 4)þ 9 (4� 2x)
¼
For each problem expand onlythe calculations indicated by the arrows
Q1. �3 (2x� 4)þ 9 (4� 2x)#
¼Q2. �3 (2x� 4)þ 9 (4� 2x)
#¼
Q3. �3 (2x� 4)þ 9 (4� 2x)#
¼Q4. �3 (2x� 4)þ 9 (4� 2x)
#¼
Examples of worked examples provided in Experiment 1
Worked-example for the integrated group Worked-example for the isolated group
�3 (5x� 2)þ 9 (7� 2x) �3 (5x� 2)þ 9 (7� 2x)¼�3� 5x� 3� �2þ 9 � 7þ 9 � �2x #¼�15xþ 6þ 63� 18x. # ¼�3 � 5x
¼�15x
#Note: students were required to stop at this stage, and not group the terms together further, thus emphasizing theconcept of bracket expansion only.
Copyright # 2006 John Wiley & Sons, Ltd. Appl. Cognit. Psychol. 20: 287–298 (2006)
298 P. Ayres