Reducing Cognitive Load by Mixing Auditory and Visual ... · Reducing Cognitive Load by Mixing Auditory and Visual Presentation Modes Seyed Yaghoub Mousavi, Renae Low, ... Findings

Journal of Educational Psychology1995, Vol. 87, No. 2, 319-334

Copyright 1995 by the American Psychological Association, Inc." 0022-0663/95/$3.00

Reducing Cognitive Load by Mixing Auditory andVisual Presentation Modes

Seyed Yaghoub Mousavi, Renae Low, and John SwellerUniversity of New South Wales

This article reports findings on the use of a partly auditory and partly visual mode ofpresentation for geometry worked examples. The logic was based on the split-attention effectand the effect of presentation modality on working memory. The split-attention effect occurswhen students must split their attention between multiple sources of information, whichresults in a heavy cognitive load. Presentation-modality effects suggest that working memoryhas partially independent processors for handling visual and auditory material. Effectiveworking memory may be increased by presenting material in a mixed rather than a unitarymode. If so, the negative consequences of split attention in geometry might be ameliorated bypresenting geometry statements in auditory, rather than visual, form. The results of 6experiments supported this hypothesis.

In recent years, working memory limitations have beenidentified as a major factor that needs to be considered wheninstruction is designed. Researchers have used cognitiveload theory (e.g., Sweller, 1988, 1989, 1993, 1994) to sug-gest that many commonly used instructional procedures areinadequate because they require learners to engage in un-necessary cognitive activities that impose a heavy workingmemory load. Alternatives that reduce extraneous cognitiveload have been devised. This research has been generated bythe following assumptions concerning our basic cognitivearchitecture: (a) People have a very limited working mem-ory that is able to hold and process only a few items ofinformation at a time; (b) People have a huge long-termmemory that is effectively unlimited in size; (c) Schemaacquisition is a primary learning mechanism. Schemata aredefined as cognitive constructs that permit people to cate-gorize information in the manner in which it will be used(see Low & Over, 1990, 1992; Low, Over, Doolan, &Michell, 1994; Sweller & Low, 1992). Schemata have the

Seyed Yaghoub Mousavi, Renae Low, and John Sweller, Schoolof Education Studies, University of New South Wales, Sydney,Australia.

The work reported in this article was supported by a grant fromthe Australian Research Council to John Sweller.

We acknowledge the assistance of the New South Wales De-partment of School Education for cooperation in data collection.We are grateful for the assistance of John Ward, director ofeducational programs and planning, New South Wales Departmentof School Education; Mary Fyfe, principal, Our Lady of the SacredHeart College; Ancilla White, principal, Our Lady of the RosaryPrimary School; Ted Edwards, principal, South Sydney HighSchool; Gavin Patterson, principal, Eastlakes Public School; RitaHayes, principal, St. Mary's High School; Jeff Wallace, principal,Keira High School; and Kevin Riolo, principal, Wollongong HighSchool.

Correspondence concerning this article should be addressed toJohn Sweller, School of Education Studies, University of NewSouth Wales, Sydney 2052, Australia. Electronic mail may be sentvia Internet to [email protected].

functions of storing information in long-term memory andof reducing working memory load by permitting people totreat multiple elements of information as a single element;(d) Automation of cognitive processes, including automaticuse of schemata, is a learning mechanism that also reducesworking memory load by effectively bypassing workingmemory. Automated information can be processed withoutconscious effort.

A limited working memory is central to this architectureand central to cognitive load theory. Recent work has ex-panded researchers' knowledge of working memory char-acteristics and in turn, this work has the potential to expandthe instructional techniques generated by cognitive loadtheory. In this article, we discuss the split-attention effectthat previous research has suggested is a cognitive loadphenomenon. The split-attention effect occurs when learn-ers are required to divide their attention among and mentallyintegrate multiple sources of information. Mentally integrat-ing multiple sources of information results in less effectiveacquisition of information than if learners are presented thesame material in a physically integrated form. A physicallyintegrated format reduces the load on working memory.

We suggest that some obstacles associated with workingmemory limits can be ameliorated by using dual-modalitypresentation techniques. Some of the recent evidence will bereviewed that indicates the existence of separate workingmemory channels or processors for auditory (especiallyverbal) and visual (especially pictorial) information. Thiswork on modality effects has suggested that effective work-ing memory capacity may be enlarged by using multiplechannels. If so, the cognitive load associated with splitattention may be reduced by presenting information with adual rather than a unitary mode. We tested this hypothesis ina series of geometry learning experiments.

Split-Attention Effect

Assume students are presented with a geometry workedexample of the type depicted in Figure 1. To understand this

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320 S. MOUSAVI, R. LOW, AND J. SWELLER

Problem Statements

Given: O is the center of the circle.

AB = CB

Prove: A ABO = ACBO

Proof Statements

1) AO = CO ( radii of the circle)

2) AB = CB ( Given).

3) BO = BO (a common side of the triangles).

4) A ABO = A CBO (SSS Theorem).

Figure 1. First worked example in Experiments 1-4. Auditory-visual and simultaneous groups heard the problem and proofstatements.

example, students must simultaneously hold in workingmemory both the diagrammatic information and the infor-mation associated with the statements. In addition, the stu-dents must mentally integrate the statements with the dia-gram by holding a statement in memory and searching forthe appropriate referents in the diagram. The statementsalone are meaningless. Searching for relations between thediagram and statements requires working memory re-sources. The cognitive load associated with this search isextraneous. It is imposed purely because of the manner inwhich the material is presented. Furthermore, the cognitiveactivities associated with searching for relations betweenthe diagram and the statements are irrelevant to schemaacquisition.

Many experiments in various areas have demonstratedthat the cognitive load consequences of split attention canbe eliminated by physically integrating multiple sources ofinformation (Chandler & Sweller, 1991, 1992; Sweller &Chandler, 1994; Sweller, Chandler, Tierney, & Cooper,1990; Tarmizi & Sweller, 1988; Ward & Sweller, 1990).For example, placing the statements associated with a dia-gram at appropriate locations on the diagram can dramati-cally facilitate learning. Eliminating the need to search forrelations between the diagram and the statements reducesworking memory load thus freeing resources for schemaacquisition.

Mayer and his colleagues have provided two lines of

research that can be related to the split-attention effect.First, Mayer (1989) and Mayer and Gallini (1990) foundthat discrete text and unlabeled diagrams were ineffectivecompared with text and diagrams with appropriately placedlabels connecting the text with the diagram. Placing labelson a diagram is likely to be analogous to physically inte-grating two sources of information. Second, Mayer andAnderson (1991,1992) found that animation and associatednarration were most effective when presented simulta-neously rather than sequentially. Mayer and Anderson(1992) labeled this effect the "contiguity principle" (p. 444).There is every reason to suppose that this finding providesa temporal example of split attention.

Physically integrating multiple sources of informationfacilitates learning by reducing working memory load. Al-though reducing extraneous cognitive activities that imposea heavy load on working memory is an obvious way offacilitating learning, similar effects should be obtainable byincreasing the amount of information that can be held inworking memory. In other words, an alternative to reducingworking memory load is to increase its effective size. In thenext section we discuss some basic characteristics of work-ing memory that may be used to increase the informationheld in that store.

Modality Effects

Currently, many memory theorists assume that there aremultiple working memory stores, rather than a unitary one.The multiple stores, streams, channels, or processors (theterminology varies) most frequently are associated withauditory or visual processing. For example, Baddeley(1992) suggested a central executive and two supportingsystems, a "visual-spatial sketch pad" (p. 556) for dealingwith visual images and a "phonological loop" (p. 556) forprocessing verbal information. The two supporting sys-tems are assumed to process their different types of infor-mation in a largely independent fashion. This conception issimilar to the dual-coding theory of Paivio (1990), al-though he places less emphasis on working memory and itslimitations.

If the two systems are independent, then the amount ofinformation that can be processed by working memory may,in part, be determined by the modality (auditory or visual)of presentation. The effective size of working memory maybe increased by presenting information in a mixed (auditoryand visual mode) rather than in a single mode.

In fact, there is evidence that a mixed mode of presenta-tion can increase the amount processed by working mem-ory. Penney (1989) reviewed the evidence for the separateauditory and visual processors hypothesis. She consideredresearch in which material is presented in either an auditoryor visual mode. Several lines of evidence for the hypothesis,with the first two being of current interest, were presented.

The first line of research demonstrated that if people areasked to perform two tasks concurrently, performance isimproved if the two tasks are presented in different modal-ities rather than in the same modality. For example, Allport,

REDUCING COGNITIVE LOAD 321

Antonis, and Reynolds (1972) found that people could at-tend to and repeat (shadow) continuous auditory speechwhile processing unrelated visual scenes or sightreadingpiano music. Additional work indicated that while shadow-ing, if participants were presented with a series of words toremember, recall was worse if the words were presented inauditory rather than visual mode. (The two auditory mes-sages were presented to different ears.) Hearing words whilelistening to speech interfered with memory of those wordsmore than did reading them. This result suggests that morecapacity is available when two modalities are used ratherthan one.

The second, related line of research measures the amountpeople recall when presented with material in a dual ratherthan a unitary mode. For example, Frick (1984) found thatif people were presented visually with a set of items fol-lowed by a series of auditory items, recall was better than itwas if both sets of items were presented in either theauditory or the visual mode. (The dual mode result wasobtained only if participants were required to report theauditory items first.) Findings such as these provide directevidence of the enhancement of working memory underdual- as opposed to single-mode conditions.

There is other work pointing to the conclusion that work-ing memory can be enhanced by processing in a dual ratherthan a unitary mode. Brooks (1967) found that if peoplewere given a complex message that needed to be visualized(e.g., a verbal description of a layout that needed to bevisualized before it could be understood), recall of themessage was enhanced if it was presented solely in auditorymode rather than a combination of auditory and visualmodes in which people simultaneously had to listen to andread the message. Inclusion of written material, because itinvolved visual presentation, apparently interfered with thevisualization needed to recall the message. Levin andDivine-Hawkins (1974) presented children with prose pas-sages that they either had to listen to or read. Half of thechildren were requested to visualize the story content. On asubsequent test of content knowledge, children who listenedto the story performed better than those who read it but onlyunder visualization conditions. Visualization improved per-formance only when the visual system was not required toprocess the original material.

In combination, the evidence of enhanced working mem-ory capacity under dual-mode conditions is very strong.Although some of the effects have been known for over twodecades, as far as we know, they have never been applied ina classroom instructional context. This issue is discussednext.

Dual Mode Instructional Techniques

If, as suggested by cognitive load theory, working mem-ory limitations must be a primary consideration when in-struction is designed, then we have a theoretical rationalefor the use of dual-mode instructional techniques. Effectivecognitive capacity may be increased if both auditory andvisual working memory can be used. Instruction may be

enhanced by expanding working memory limits by simul-taneous visual and aural presentation of information. ThatMayer and Anderson (1991, 1992) found that simultaneouspresentation of visual and aural material was superior tosuccessive presentation lends cogency to the argument.Mayer and Anderson, and Paivio (1990), argued that audi-tory and visual material is processed by separate but inter-dependent systems.

Consider Figure 1 again; it consists of a diagram and textthat need to be integrated before they can be understood. Asindicated earlier, mental integration of these two sources ofinformation requires working memory resources, and as aconsequence, these resources are unavailable for learning. Ifworking memory resources can be enhanced by dual-modepresentation, then learning may be facilitated. Although thediagram obviously should be presented in its natural, visualmode, the associated statements can be presented aurallyjust as easily as visually. Simultaneous aural presentation ofthe statements and visual presentation of the diagram mayameliorate the negative consequences of split attention. Amixed-mode presentation may enhance learning comparedto a purely visual mode because of the effective expansionof working memory capacity. In the experiments in thisarticle, we test this hypothesis as an alternative to reducingcognitive load by physically integrating the diagram andstatements.

Experiment 1

Our purpose in Experiment 1 was to compare three modesof presenting geometry worked examples. One group ofstudents (simultaneous group) studied worked exampleswith the diagram and its associated statements presentedvisually and heard the statements played from a tape re-corder simultaneously. Thus, with reference to Figure 1, thisgroup could, for example, see the diagram, read the firstproof statement, "AO = CO (radii of the circle)" whilesimultaneously hearing this proof statement from the taperecorder. For this group, the visual statements and thediagram constitute a split-attention format and should im-pose a heavy cognitive load. Alternatively, if studentschoose to ignore the visual statements and attend to theauditory statements instead, the consequences of split-atten-tion may be eliminated and effective working memoryincreased because of the use of dual-sensory modes.

Another group of students (visual-visual group) receivedworked examples in which both the diagram and its asso-ciated statements were presented visually only. This groupdid not hear the statements. Split attention and its concom-itant cognitive load was unavoidable for this group. Thethird group of students (visual-auditory group) studiedworked examples in which the diagram was presented vi-sually while they were also listening to the audio tape of itsassociated statements. The written version of the statementswas not available. This group should have an unambigu-ously reduced cognitive load if, as hypothesized above,students can process the auditory statements while simulta-neously attending to the diagram. It was predicted that the


performance of the visual—auditory group would be superiorto that of the visual-visual group and possibly to that of thesimultaneous group (if the simultaneous group chose toattend more to the written than auditory input when dealingwith the statements) because of an expansion of effectiveworking memory capacity.

Method

Participants. The participants were 30 Year-8 {equivalent toeighth grade in the United States) students from two Wollongong,Australia high schools. The 15 students with the highest gradeswere selected from one top mathematics class in each high school.These classes were chosen after pilot studies indicated that thestudents' level of accomplishment in geometry was sufficient toallow them to complete the problem sets after some additionalstudy.

Procedure. The day before the experiment, all participantswere told that they would be taking a geometry test. No instructionwas given concerning the context. All students were tested indi-vidually. The procedure consisted of an explanatory, an acquisi-tion, and a test phase. The explanatory phase consisted of an initial,written explanation sheet that provided a maximum 5-min periodof instruction to familiarize students with the basic principles ofcongruent triangles, emphasizing the "side-side-side" (SSS) theo-rem and the links with circle and square geometry. Students wereasked if they had any questions, and questions were answered untilstudents were satisfied that they understood the material.

An "acquisition" or learning phase followed the explanatoryphase. In this phase four problems were presented: Two problemswere presented as worked examples (see Figures 1 and 2), and twoproblems similar to the worked examples were presented as repeatproblems requiring solution. The first worked example problem(Figure 1) demonstrated relations between congruent triangles andcircle geometry, whereas the second (Figure 2) related congruenttriangles and the geometry of squares. Study times for the exam-ples as well as solution times and errors for the problems wererecorded for each participant.

There were three groups of 10 participants per group. Partici-pants were randomly assigned but there were equal numbers ofparticipants from each class in each group. The acquisition treat-ment differed among the three groups. The participants in thesimultaneous group were given the diagram and its associatedproblem and proof statements on a sheet of paper while theysimultaneously heard the statements played from a tape recorder(see Figures 1 and 2). Members of the simultaneous group wereinformed that they should study the worked example writtenmaterial and listen to the tape recording carefully until they un-derstood it because the following problem that they had to solvewas similar. The participants in the visual-visual group followedthe same procedure except that they only had the written materialswith no auditory component. The participants in the visual-auditory group were presented with the diagram but not a writtenversion of the statements. While looking at the diagram, thevisual-auditory group heard the audio tape of the statements.

Participants in the visual-visual group could study their mate-rials for as long as they wished up to a maximum of 5 min. Thesimultaneous and visual—auditory groups were required to listen tothe tape twice, and the tape playing time determined their studytime, which as a consequence, was identical for all participants inthese two groups. (There was no study time allocated other thanwhen the tape was playing.) Following the first worked example,all groups were given a similar (repeat) problem to solve. An

Problem Statements

Given: XY is a diagonal of the square XTYR.

Prove: AXTY =AXRY

Proof Statements

1) XT = XR ( sides of the square).

2) YT = YR ( sides of the square)

3) XY = XY ( a common side of the triangles)

4) A XTY =A XRY ( SSS Theorem).

Figure 2. Second worked example in Experiments 1-4.Auditory-visual and simultaneous groups heard the problem andproof statements.

identical procedure was followed for the second worked exampleand its associated problem.

While participants were solving the problems, whenever an errorwas detected, they were informed that an error had been made thatshould be corrected before proceeding. Participants were allowedmultiple solution attempts until the maximum time of 5 min hadlapsed. If the correct solution was not obtained during this period,they were shown the solution.

A test phase following the acquisition phase was identical for allgroups. The test phase consisted of two sets of two problems each.The first set was similar to the initial problems (Figures 1 and 2)in the acquisition phase. The second set, which consisted oftransfer problems, differed from the initial problems in that itrequired use of the same geometric theorems in a different dia-grammatic context (see Figures 3 and 4). Errors were not cor-rected. If participants provided an incorrect solution they wereinformed that it was incorrect and were asked to attempt thesolution again. Multiple solution attempts were permitted until thecorrect solution was attained or until the maximum time of 5 minhad elapsed. Participants who did not provide a correct solutionwithin the maximum time were not shown the correct solution butwere required to commence the next problem. Solution times anderrors for all problems were recorded for each participant, withnonsolvers (those who had either not completed solution or whohad completed one or more incorrect solutions without providinga correct solution) allocated the maximum time of 300 s. Thisapproach was based on the assumption that nonsolvers' perfor-mance was worse than that of any student who correctly solved aproblem within the time limit. Participants did not have access toprior materials or work at any stage of the acquisition or testphases.


Problem Statements

Given: H is the center of the circle.

LG = KG

Prove: A LHG = A KHG

Figure 3. First transfer example in Experiments 1-4.

Results and Discussion

The number of seconds taken by each group during bothacquisition and test phases was compared. Table 1 indicatesthe mean number of seconds for solution for the threegroups on the acquisition problems. Mean times were basedon all participants, regardless of whether the proof wassuccessfully completed. Participants who did not complete aproof were awarded a score of 300 s. It could be argued thatawarding maximum time scores to nonsolvers (a) is biasedin favor of the present hypotheses insofar as conditions withlarger numbers of nonsolvers are inappropriately penalizedand (b) is likely to produce markedly skewed distributions.To be conservative, therefore, we reanalyzed all measures ineach experiment with nonsolvers' times defined as 10 smore than the highest solver's times for that measure. In allcases, the statistical pattern of results was the same for thetwo scoring systems.

Because the visual-auditory and simultaneous groupswere presented with the same audio-taped recording of theworked examples statements, the time was identical for allparticipants and so time spent studying worked exampleswas ignored. Table 1 indicates the mean number of secondsfor solution for the three groups on Problems 2 and 4, whichwere presented as repeat problems (i.e., similar to theworked examples) for all groups. There was a significantdifference in the combined times of the two problems be-tween the three groups, F(2, 27) = 5.92, MSE = 5,695.27.(The 0.05 level of significance was used for all analysesexcept when stated otherwise.) Newman-Keuls testsshowed that the visual—auditory group required less time tosolve the problems than did the visual-visual group. Thesimultaneous group also took less time to solve the prob-lems than did the visual—visual group. There was no signif-icant difference between the simultaneous and visual-auditory groups.

Our major question is whether differential acquisitiontreatments have had consequences during the test phase. If

the visual-auditory group had a reduced cognitive loadcompared with the other two groups, and if as a conse-quence, learning has been enhanced, we might expect su-perior test performance by the visual-auditory group.

Table 1 indicates the mean times taken by the threegroups to solve the four test problems. For the combined,similar test problems, there was a significant differencebetween the three groups, F(2, 27) = 4.81, MSE =4,644.53. Newman-Keuls tests showed that the visual-auditory group spent less time solving the problems than didthe visual-visual and the simultaneous groups. There wasno significant difference between the simultaneous and thevisual-visual groups. On the transfer problems, although thevisual-auditory group again solved the problems more rap-idly than did the other two groups, the differences were notsignificant, F(2, 27) = 2.44, MSE = 11,105.28.

Table 1 also indicates the number of nonsolvers duringthe acquisition and test phases. As can be seen, with theexception of the second transfer problem, the number ofnonsolvers is very low, and differences between groups areslight.

In summary, the results of this experiment are consistentwith the hypothesis that the use of dual sensory modesreduces cognitive processing load by expanding workingmemory capacity. A mixed auditory and visual mode ofpresenting information was more effective than a single(visual) mode.

Experiment 2

The results of Experiment 1 have demonstrated that thepresentation of information in a mixed auditory and visualmode rather than in a single mode, has beneficial effects onlearning, presumably through expanding effective workingmemory capacity. However, it should be noted that thetimes taken by the visual-visual group to study workedexamples were shorter than the times of the other two

Problem Statements

Given: ABZD is a square.

W is the midpoint of BD

Prove: A DAW = A BAW

Figure 4. Second transfer example in Experiments 1-4.


Table 1Mean Seconds Spent Studying or Solving and Number of Nonsolvers for Each Groupfor Each Problem in Experiment 1

Problem and no. ofnonsolvers

Acquisition phaseFirst worked exampleFirst repeat problemNumber of nonsolversSecond worked exampleSecond repeat problemNumber of nonsolvers

Test phaseFirst similar problemNumber of nonsolversSecond similar problemNumber of nonsolversFirst transfer problemNumber of nonsolversSecond transfer problemNumber of nonsolvers

Visual-Visual

108.30224.30

284.90

155.801

147.502

87.200

136.700

202.204

Group

Simultaneous

151.00165.90

1157.00128.20

0

135.001

87.800

115.100

189.903

Visual-Auditory

151.00159.30

1157.00110.20

0

77.300

70.200

103.400

133.402

Note, n = 10 for each group.

groups, which were dictated by the audiotaped recording ofthe worked examples statements. These differences in studytimes might have contributed to the results obtained, withstudents in the visual-visual group performing worst be-cause they spent less time studying the worked examplesthan did students in the other two groups. Experiment 2 wasdesigned to equalize the presentation times of the threegroups.

Method

Participants. The participants were 30 Year-8 students fromthe top mathematics class of a Sydney, Australia metropolitan areahigh school. This class was chosen after pilot studies indicated thatthe students' level of accomplishment in geometry was sufficientto allow them to complete the problem sets after some additionalstudy.

Procedure. Ten students were randomly assigned to each ofthree groups. The general procedure was similar to that used inExperiment 1, with the only major difference being in the presen-tation time of material for the visual-visual group. In Experiment1, the presentation times for the visual-auditory and simultaneousgroups were identical, because they were determined by the tapelength, whereas for the visual—visual group, participants deter-mined presentation times. In Experiment 2, the presentation timesfor the three groups were equal. The time for the visual-visualgroup was constant for each participant and equal to the timeavailable to participants listening to the auditory tape. Participants,rather than being told to study the worked examples until theywere ready, were asked to study the examples for a fixed time.These times were 151 s and 157 s for the first and second workedexamples, respectively.


Table 2 indicates the mean number of seconds to solutionfor the three groups on the four acquisition problems. Meantimes were based on all participants, regardless of whether

the proof was successfully completed, as in Experiment 1.Participants who did not complete a proof were allocatedthe maximum time of 300 s.

The primary question examined in Experiment 2 waswhether there were significant differences in times to solu-tion as a result of differences in modes of presentation. Thedifference in times spent on the two repeat acquisitionproblems was not significant, F(2, 27) = 1.68, MSE =13,490.3. A significant difference between groups wasfound on the two similar test problems, F(2, 27) = 3.74,MSE = 1,838.39. Newman-Keuls tests showed that thevisual—auditory group spent less time to solve the problemsthan did the visual-visual group. There were no significantdifferences between the simultaneous group and the othertwo groups. On the transfer problems, although the visual-auditory group again solved the problems more rapidly thandid the other two groups, the differences were not signifi-cant, F(2, 27) = 2.09, MSE = 9,718.36.

Table 2 indicates the number of nonsolvers. As was thecase for Experiment 1, there were few nonsolvers.

Overall, the pattern of results of this experiment is similarto that found in Experiment 1 (except that there were nosignificant differences on the repeat acquisition problems).We were able to conclude that the differences found in bothExperiments 1 and 2 were not due to differential acquisitiontimes. Rather, the results were consistent with the hypoth-esis that presenting the worked examples in a dual modeformat expanded effective working memory, thus allowingthem to be processed more effectively.

Experiment 3

Experiments 1 and 2 demonstrated the beneficial effectsof presenting instructional material in a mixed auditory andvisual mode. This finding is in accordance with the sugges-tion that effective working memory capacity may be in-




Acquisition phaseFirst repeat problemNumber of nonsolversSecond repeat problemNumber of nonsolvers


Visual-Visual

150.401

128.001

61.100

79.900

66.800

173.503

Group

Simultaneous

154.601

127.201

60.600

63.100

59.200

137.102

Visual-Auditory

93.300

104.400

42.300

47.200

51.600

98.601


creased if both auditory and visual working memory can beused.

However, the superiority of the visual-auditory presenta-tion mode over the visual-visual presentation mode foundin Experiments 1 and 2 is open to an alternative explanation.Assume that in the visual-visual presentation mode it isnecessary to hold in working memory information from onesource (e.g., the statements) when information from anothersource (e.g., the diagram) is being processed. Because thestatements and the diagram cannot be viewed simulta-neously, students are likely to need to read a statement, holdit in working memory, and then attend to the diagram tointegrate it with the statement. Although attention may beshifted between sources of information rapidly, neverthe-less, it is not possible to look at the diagram and read astatement simultaneously. The act of holding a statement inworking memory and then attending to the diagram may beunnecessary for the visual-auditory group, which may beable to attend to both simultaneously. Differences betweena visual-visual group and a visual-auditory group may bedue entirely to the visual-visual group having to hold ma-terial from one source of information in working memorybefore attending to the other source. This difference maydisappear if the visual-auditory group is forced to similarlyhold material in working memory.

The cognitive load hypothesis is that working memorycapacity is increased with a dual mode of presentation, thusmaking it easier for students to integrate the diagrams andstatements irrespective of whether they are attended tosimultaneously or successively. Under this hypothesis, forc-ing a visual-auditory group to process the information suc-cessively, as occurs for a visual-visual group, should noteliminate its advantage. The increased working memorycapacity available when using a dual mode of presentationshould still be available even if students must hold anauditory statement in memory before viewing the diagram.The increased capacity should still make it easier to men-tally integrate the diagram and the statements than a visual-visual presentation.

We designed Experiment 3 to test these two hypothesesby comparing four modes of presenting geometry workedexamples: a visual-visual mode and a visual-auditory modeunder either simultaneous or sequential presentation condi-tions. The two simultaneous modes presented the diagramand its associated statements at the same time. The simul-taneous modes were identical to the presentation modesgiven to the visual-visual and visual-auditory groups ofExperiment 1. The two sequential modes presented studentswith the statements and the diagram sequentially, ratherthan simultaneously, requiring them to hold in workingmemory information to which they had just attended, byblocking all other relevant information. Thus, for example,when students saw or heard the statements, they could notsee the diagram because it was covered. Similarly whenthey saw the diagram, they could not see or hear the state-ments. If the difference between groups is due to studentshaving to hold in working memory information they hadearlier processed while attending to new information, thenthere should be a difference between the two simultaneousgroups but no difference between the two sequential groups.Alternatively, if the difference is not due to students needingto hold in working memory information they had earlierprocessed while processing incoming information, butrather is due to increased memory capacity being availablewhen a dual mode of presentation is used, the differenceexpected for the two simultaneous groups is also to beexpected for the two sequential groups.

Method

Participants. The participants were 40 Year-8 students fromthe two top mathematics classes of a Wollongong, Australia highschool. These classes were chosen after pilot studies indicated thatthe students' level of accomplishment in geometry was sufficientto allow them to complete the problem sets after some additionalstudy.

Procedure. This experiment again was conducted in threephases. The first phase was the explanatory phase. The procedure


and the instructional material for this phase were identical to thoseused in Experiments 1 and 2.

An acquisition phase followed in which students were given aset of four acquisition problems identical in content to those ofExperiments 1 and 2. Again, Problems 1 and 3 were in the form ofworked examples, whereas Problems 2 and 4 took the form ofsimilar ("repeat") problems that students were required to solve.

Participants were randomly allocated to one of either twovisual-visual groups or two visual-auditory groups, with 10 par-ticipants per group. The procedure for the initial worked examples(1 and 3) for the simultaneous visual-visual group and the simul-taneous visual-auditory group was the same as for the visual-visual group and the visual-auditory group in Experiment 1. Forthe sequential visual-visual group, the experimenter showed stu-dents the first line of the first worked example (in Figure 1,"Given: O is the center of the circle") with the remaining sevenlines and the diagram covered. When the participant had read theline, the experimenter covered all the statements and revealed thediagram. When the participant was ready, the experimenter thenshowed the second line of the first worked example ("AB = CB")while covering all the other lines, including the first line and thediagram. This procedure of revealing only one line at a time andthen the diagram alone was followed until every problem andproof statement line of the worked example was completed. Anidentical procedure then was used for the second worked example.

For the sequential visual-auditory group the experimenterplayed the first line of the first worked example problem using acassette record player and keeping the diagram covered. Thediagram was revealed after the first line was played. The partici-pant indicated when he or she was ready for the next line. Thediagram was recovered, and the procedure was repeated for thesecond line. This procedure was followed until every line of theworked example was completed. An identical procedure was fol-lowed for the second worked example. The procedure for therepeat acquisition problems and test problems for all four groupswas identical to that used in Experiments 1 and 2.


Table 3 shows the mean number of seconds to solve eachproblem. The performance of each group during bothacquisition and test phases was compared. The simulta-neous visual-visual group spent less time studying theirworked examples than did the simultaneous visual-auditorygroup, which had a fixed time determined by the tapelength. The sequential visual-visual group also spent lesstime studying worked examples than did the sequentialvisual-auditory group. (Unlike the simultaneous visual-auditory group, the sequential equivalent did not have afixed study period because the time to study diagramsvaried between students.)

Table 3 indicates the mean number of seconds to solutionfor the four groups on the two repeat problems. A 2 X 2analysis of variance (ANOVA) indicated a significant mo-dality (visual-visual vs. visual-auditory) effect, F(l, 36) =11.18, MSE = 16,800.11, with the visual-auditory groupsrequiring less time to solve the two repeat problems. Therewas no significant effect that was due to presentation se-quence (simultaneous vs. sequential) and no significantmodality by presentation sequence interaction, both Fs < 1.The lack of a significant interaction suggests that the ad-vantage of the visual-auditory procedure occurs irrespectiveof whether the material is presented simultaneously or suc-cessively. Specifically, successive presentation of the audi-tory and visual material has not destroyed the advantage ofthe visual-auditory procedure.

With respect to the test phase, the differences betweenconditions on the two similar problems, also indicated asignificant modality effect, F(l, 36) = 12.88, MSE =5,627.56; again this was due to a visual-auditory advantage.There was no significant effect that was due to presentation





Simultaneous

Visual-Visual

111.40180.60

274.10

163.702

113.000

92.400

72.300

131.102

Group

Sequential

Visual-Auditory Visual-Visual Visual-Auditory

151.00128.40

0157.0088.30

0

63.800

48.500

54.900

100.500

159.50206.50

4144.90156.80

2

100.100

76.900

89.200

162.800

251.80101.80

0224.90115.00

0

47.700

52.100

65.400

108.400



sequence and no significant interaction, both Fs < 1. Again,the fact that we did not find a significant interaction sug-gests that using the visual-auditory procedure is advanta-geous even when information from the two modes cannot beprocessed simultaneously. Analyses of the differences be-tween conditions on the two transfer problems indicated aneffect that was due to modality, favoring the visual-auditorygroup, F(l, 36) = 3.63, MSE = 10,965.57, p < .05 (one-tailed), but no effect that was due to presentation sequence,F(l, 36) = 1.02, MSE = 10,965.57, nor an interaction effect(F < 1).

Table 3 indicates the number of nonsolvers for eachproblem. As can be seen, there were very few nonsolvers.

The results of this experiment demonstrated that regard-less of whether the two sources of information (diagramand statements) were altered to simultaneous or successivepresentation, a dual mode of presentation was superior.This finding suggests that the advantage of the dual modeover the single mode of presentation is not due to having tohold material from one source of information in work-ing memory before attending to the other source in singlemode processing. The superiority of the sequential visual-auditory group over the sequential visual-visual was just asmarked as the superiority of the simultaneous visual-auditory group over the simultaneous visual-visual group.On the basis of these results, the advantage of the dualmode over the single mode of presentation is more likely toderive from an expanded memory capacity rather than fromthe need for visual-visual students to hold informationfrom the statements in working memory before attending tothe diagram.

It might be noted, that on the surface, the results ofExperiment 3 might appear to contradict those of Mayer andAnderson (1991, 1992) who found that simultaneous audi-tory and visual presentation was superior to successive. Infact, cognitive load theory can explain both sets of results(R. E. Mayer, personal communication, May 2, 1994). Inthe Mayer and Anderson studies, relatively large blocks ofanimation and narration were presented successively ratherthan in the line-by-line presentation of Experiment 3. Theselarge blocks are likely to have imposed a heavy workingmemory burden, thus resulting in poor performance by thesuccessive-presentation groups.

Experiment 4

The results of Experiment 3 suggest that the superiority ofthe mixed auditory and visual presentation over the singlevisual mode presentation found in Experiments 1 and 2 wasnot due solely to the suggestion that, in the visual mode butnot in the mixed auditory and visual modes of presentation,students need to hold in working memory information re-quired to process new information. Rather, the results aremore likely to be due to an expanded effective workingmemory capacity. However, as in Experiment 1, the studytimes for the single-mode groups were shorter than theywere for the corresponding mixed auditory and visualgroups. We designed Experiment 4 to equalize study times

by allowing students in the visual-visual groups the sametime to go through the worked examples as was taken by thecorresponding auditory groups.

Method

Participants. The participants were 40 Year-8 students fromthe top two classes of a Sydney, Australia metropolitan area highschool. These students were chosen after pilot studies indicatedthat their level of accomplishment in geometry was sufficient toallow them to complete the problem sets after some additionalstudy.

Procedure. The general procedure was similar to that used inExperiment 3, with the major difference being in the acquisitionpresentation times of worked examples. In Experiment 3, thepresentation times of materials for the two visual-auditory groupswere not identical to those of the two visual-visual groups. In thisexperiment, for the simultaneous presentation condition the timefor the visual-visual group was constant for each participant andwas equal to the time available to participants listening to theauditory tape (as in Experiment 2). For the sequential presentationcondition, the time available to the visual-visual group to readeach statement was identical to the auditory tape playing time forthat statement. The time available to study the diagram after eachstatement was heard or read was determined by the time requiredby the first participant in the visual-auditory group. All otherparticipants were allocated the same times for each view of thediagram. In this manner, study times were equalized for eachworked example for both groups.


The performance of each group during both the acquisi-tion and the test phases was compared. Table 4 shows themean time spent on each problem by each group.

With respect to the two repeat problems, a 2 X 2 ANOVAindicated no significant effects: modality, F(l, 36) = 2.67,MSE = 7,182.43; presentation sequence and interaction,both Fs < 1. With respect to the test phase, the differencesbetween conditions on the two similar test problems indi-cated a significant modality effect, F(l, 36) = 7.31, MSE =2,956.58, with the visual—auditory groups demonstratingsuperiority over the visual-visual groups. There was noeffect that was due to presentation sequence (simultaneousvs. sequential) and no significant interaction, both Fs < 1,thus indicating that the use of a sequential presentationprocedure did not eliminate the modality effect. The differ-ences between conditions on the two transfer problems alsoindicated a significant modality effect, F(l, 36) = 5.29,MSE = 8,934.75, but no effects that were due to presenta-tion sequence nor to the interaction, both Fs < 1, thusreplicating the results for the similar test problems.

Table 4 indicates the number of nonsolvers for eachproblem. As for the previous experiments, there were veryfew nonsolvers, and differences between groups were slight.

The results of this experiment are consistent with thoseobtained in Experiment 3. Again, the results indicate thebeneficial effects of presenting instructional material in amixed auditory and visual mode. The fact that we did notobtain a significant interaction indicates that the modality






Simultaneous

Visual-Visual

151.00128.10

2157.00129.20

1

74.100

65.100

76.200

172.701

Group

Sequential

Visual-Auditory Visual-Visual Visual-Auditory

151.0098.10

1157.0091.100

50.900

45.200

50.500

120.501

210.00119.60

0190.00117.60

1

71.800

75.500

71.500

166.902

210.00112.50

0190.00105.20

0

47.200

50.200

51.200

127.601


effect is probably due to increased working memory capac-ity under dual-mode presentation conditions rather than tosequential or simultaneous presentation of information.

Experiment 5

The previous four experiments, which were based ongeometry worked examples, suggest that effective cognitivecapacity may be increased if both auditory and visual work-ing memory can be used. Results indicated that a mixedauditory and visual mode presentation was superior to asingle visual mode presentation when the problem consistedof a diagram and the solution consisted of text. However,the theory used to generate the experiments is quite generaland should not be restricted to instructional materials inwhich one source of information is a diagram and the otherconsists of text.

We designed Experiment 5 to test the mixed-mode effectwith mathematical problems in which both sources of in-formation consisted of verbal statements, rather than a dia-gram and statements. Four modes of presenting workedexamples concerning the dimensions of a rectangle werecompared. Whereas the verbal-written mode presented boththe problem information and the solution statements in avisual sentence format, the verbal-auditory mode presentedthe problem information in a visual sentence format andthe solution statements aurally from a tape recorder. Thediagram-written mode presented the problem informationas a diagram and the solution statements in written form,whereas the diagram-auditory mode presented the probleminformation as a diagram and the solution statements au-rally. In accordance with cognitive load theory and theresults of the four experiments reported earlier, we predictedthat the performance of students who learned under theverbal-auditory and the diagram-auditory conditions would

be superior to that of students who learned under the verbal-written and diagram-written conditions, respectively.

Method

Participants. The participants were 40 Year-4 students (equiv-alent to US 4th graders) randomly chosen from a Sydney, Australiametropolitan area primary public school. None had any prior,formal training in geometry.

Procedure. All students were tested individually. The proce-dure consisted of three phases. The explanatory phase, with aninitial, written explanatory sheet, provided a maximum 5 minperiod of instruction to familiarize students with the basic princi-ples of rectangles with an emphasis on the perimeter.

An "acquisition" or learning phase followed the explanatoryphase. Two similar problems were presented as worked examples(see Figure 5 for an example). The worked examples were iden-tical in format, with the only difference being in the numericalvalues used. Each of the worked examples consisted of twosources of information: (a) the problem presented either in dia-grammatic or written verbal format and (b) a set of statementsreferring to relations between elements of the problem presentedeither visually (written) or aurally (from a tape recorder). Attentionhad to be divided between the problem and the set of statements.The time for the four groups was constant for each participant andequal to the time available to participants listening to the auditorytape. All students were required to study each worked example fora fixed period of 60 s before going on to the next similar ("repeat")problem. A maximum of 3 min was allowed to solve each prob-lem. Students were informed of any incorrect solutions and wereallowed additional attempts until the maximum time had elapsed.If the correct solution was not obtained during this period, thestudent was shown the solution.

Students were assigned randomly to the four groups, with 10students per group. Each group was given the same materials withdifferent presentation formats. The verbal-written group receivedthe problems and the set of statements both in a visual sentenceformat. The verbal-auditory group received the problems visually


Problem Statements

The length of a rectangle is 3 cm. Its width is 1 cm.

What is the perimeter

of the rectangle?

Answer

Length + width = 3 cm + 1 cm

= 4 cm

The perimeter = 4 cm x 2

= 8 cm

Figure 5. A worked example used in Experiment 5. The verbal-written group received the problem and the answer both in visualsentence format. The verbal-auditory group received the problemvisually in sentence form and the answer aurally from a taperecorder. The diagram-written group received the problem as adiagram and the answer in written form. The diagram-auditorygroup received the problem as a diagram and the answer aurallyfrom a tape recorder.

in sentence form and the set of statements aurally from a taperecorder. The diagram—written group received the problems as adiagram and the statements in written form. The diagram-auditorygroup received the problems visually and the statement aurallyfrom a tape recorder.

The test phase following the acquisition phase was identical forall groups. The test phase consisted of two sets of two problemseach. The first set was similar to the worked example problems inthe acquisition phase. The second set, which consisted of transferproblems, was different from the worked example problems in thatit required using the same geometric procedures in a differentcontext (see Figure 6). Each problem consisted of a verbal problemstatement, a diagram, and the question. During the test phase of theexperiment, participants did not have access to previous workcarried out during any phase of the experiment or to previouslyseen example problems.

Table 5 indicates the mean number of seconds to solutionfor the four groups on the two repeat problems. A 2 X 2ANOVA indicated significant main effects: problem pre-sentation format, F(l, 36) = 5.93, MSE = 4,925.09, indi-cating that a diagrammatic presentation was superior to averbal presentation; statement presentation format, F(l,36) = 17.88, indicating that an auditory presentation of thestatement was superior to a written presentation. There wasno significant interaction (F < 1) suggesting that auditorystatements resulted in an equivalent improvement whetherpaired with written or diagrammatic problems.

With respect to the test phase, if the two groups, verbal-auditory and diagram-auditory, had a reduced cognitiveload compared with the other two groups and if, as aconsequence, learning has been enhanced, we might expectsuperior test performance by these two groups giving asimilar pattern of results to the acquisition problems. Table5 indicates the mean number of seconds to solution pergroup for the two similar and the two transfer problems.

The differences between conditions on the two similarproblems indicated significant main effects: problem pre-sentation format, F{\, 36) = 15.32, MSE = 725.90; state-ment presentation format, F(l, 36) = 9.21. There was nosignificant interaction F(l, 36) = 1.18.

The differences between conditions on the two transferproblems also indicated significant main effects: problempresentation format, F(l, 36) = 5.51, MSE = 2,072.48;statement presentation format, F(l, 36) = 4.52. There wasno significant interaction (F < 1).

Table 5 indicates the number of nonsolvers. As wasthe case for the previous experiments, there were fewnonsolvers.

In summary, the results of this experiment demonstratethe superiority of auditory solution statements over writtensolution statements regardless of whether problem informa-tion is presented in written or diagrammatic form. Thisfinding, together with the results of the previous experi-ments can be best explained with cognitive load theory.When multiple sources of information must be mentally

Problem Statements

The length of a rectangle is 4 cm. Its width is half of its length.

What is the perimeter

of the rectangle?


The mean number of seconds taken by each group tosolve the problems during both acquisition and test phaseswere compared. Mean times were based on all participants,regardless of whether the problem was successfully com-pleted. Participants who did not complete a problem wereallocated the maximum time of 180 s. Figure 6. A transfer example used in Experiment 5.






Verbal-Written

60.00154.50

660.00

110.703

53.700

48.400

58.000

79.401

Verbal-Auditory

60.00126.00

460.0054.00

0

39.000

28.000

55.000

42.300

Group

Diagram-Written

60.00146.00

660.0073.80

1

32.100

27.400

47.500

46.600

Diagram-Auditory

60.0084.000

60.0033.300

22.600

20.300

41.900

31.100


integrated before they can be understood, working memoryresources are not available for learning. However, if the twosources of information are presented in different modalities,then learning may be facilitated by an expansion of avail-able working memory capacity.

Experiment 6

The previous five experiments demonstrated the benefi-cial effects of presenting instructional material in a mixedauditory and visual mode. This finding supports the sugges-tion that working memory capacity can be increased with adual-presentation mode. However, the superiority of themixed mode over the purely visual mode found in theprevious experiments is open to an alternative explanation.It might be argued that, in general, a visual mode of pre-sentation is more demanding than an auditory mode. Forexample, reading may be a more cognitively demandingtask than listening, perhaps because the reading process maynot have been automated. If so, the excessive cognitive loadthat may occur when reading statements may be due toreading difficulties rather than to the fact that reading solu-tion statements uses the same modality as reading problemstatements.

Experiment 6 was designed to test the possibility that theresults of the prior experiments may be due to visual pro-cesses, such as reading, being more cognitively demandingthan the listening process. With similar materials to thoseused in Experiment 5, we compared two modes of presen-tation: a visual-visual mode and an auditory-auditorymode. Whereas the visual-visual mode presented both theproblem information and the solution statements in a visualsentence format, the auditory-auditory mode presented theidentical information aurally, from a tape recorder. Wehypothesized that if the results of the previous experiments

were due to reading difficulties by students required to readrather than to hear text, then the performance of theauditory-auditory group should be superior to that of thevisual-visual group.

Method

Participants. The participants were 20 Year-4 students ran-domly chosen from a Sydney, Australia metropolitan area publicprimary school. None had any prior formal training in problemsdealing with the dimensions of a rectangle.

Procedure. All students were tested individually. The proce-dure consisted of three phases. The explanatory phase was iden-tical to that used in Experiment 5. An "acquisition" or learningphase followed. Two similar problems were presented as workedexamples (Figure 7 provides an example). The worked exampleswere identical in format, with the only difference being in thenumerical values used. As was the case in Experiment 5, each ofthe worked examples consisted of two sources of information: theproblem and a set of statements referring to relations betweenelements of the problem. Attention had to be divided between theproblem and the set of statements. Both the problem and theassociated set of statements were presented either entirely aurallyor entirely visually.

All students were required to study each worked example for afixed period of 55 s before proceeding to the following similarproblem. A maximum of 3 min was allowed for each similarproblem. Students were informed of any incorrect solutions andallowed additional attempts until the maximum time had lapsed. Ifthe correct solution was not obtained during this period the stu-dents were shown the solution.

Students were assigned randomly to the two groups, with 10students per group. Each group was given the same materials withdifferent presentation formats. The auditory-auditory group re-ceived the worked example problems and statements from a taperecorder. The visual-visual group read the worked example prob-lems and the set of statements from the written sheets.


Problem Statements

The width of a rectangle is 1 cm. Its length is 3 cm.

What is its perimeter?

1 cm + 3 cm = 4 cm

The perimeter = 4 cm x 2

= 8 cm

Figure 7. A worked example used in Experiment 6. Theauditory-auditory group heard the problem and the answer.

The test phase following the acquisition phase was identical forboth groups. The test phase consisted of two sets of two problems.The first set was similar to the worked example problems in theacquisition phase. The second set, which consisted of transferproblems, was different from the worked example problems in thatit required the students to use the same knowledge of perimeter ofa rectangle in a different context (e.g., "The perimeter of a rect-angle is 10 cm. Its length is 3 cm. What is its width?"). During thetest phase of the experiment participants did not have access toprevious work carried out during any phase of the experiment or topreviously seen example problems. No diagram was provided inthis experiment during either the acquisition or test phases.


Table 6 shows the mean number of seconds to solve eachproblem and the number of nonsolvers. The performance ofeach group during both acquisition and test phases wascompared. A / test indicated a significant difference be-tween the two groups in the acquisition phase. The visual-visual group spent less time solving their repeat problemsthan did the auditory-auditory group, t(18) = 2.12, SE =37.08.

Our major question was whether differential acquisitiontreatments have consequences during the test phase. If thelistening process is less cognitively demanding than thereading process, then we would expect superior test perfor-mance for the auditory-auditory group.

Table 6 indicates the mean number of seconds to solutionper group for each of the two similar and the transferproblems. The difference between groups on the two similarproblems was not significant, /(18) = 0.90, SE = 28.89.Similarly, there was no significant difference betweengroups on the transfer problems, f(18) = 0.21, SE = 31.43.Nevertheless, as was the case in the acquisition phase, thetimes taken to solve both the similar and transfer test prob-lems were actually shorter for the visual-visual group thanfor the auditory-auditory group.

Table 6 indicates the number of nonsolvers. There werefew nonsolvers except for the transfer tasks, which moststudents found insoluable.

In summary, the results of Experiment 6 demonstrate thatfor the students included, reading problem and solutionstatements is no more cognitively demanding than is lis-tening to the same information. In fact, the reverse may betrue: Although test differences were not found to be sig-nificant, the results provide some indication that listeningto problem statements and solution statements requiresmore cognitive resources than does reading the same infor-mation. A significant difference in solving repeat problemsduring acquisition favored the visual-visual group. It alsoshould be noted that these results were obtained withYear-4 students whose reading skills are likely to be sub-stantially inferior to those of the Year-8 students whoparticipated in Experiments 1-4.

General Discussion

We began by indicating that basic research into the char-acteristics of working memory has suggested that this pro-cessing system is divided into at least two partially inde-pendent subprocessors: an auditory system devoted heavilyto language and a visual system for handling images, in-cluding writing. Because both systems can be used simul-taneously, limited working memory capacity might be ef-fectively increased if information that must be stored orsimultaneously processed is presented in a manner thatpermits it to be divided between the two systems, rather thanprocessed in one system alone. As a consequence, informa-tionally equivalent material that may be difficult to processin a purely visual manner may be more easily handled if itcan be presented partially in both modalities.

This research into working memory modality effects can

Table 6Mean Seconds Spent Studying or Solving and Number ofNonsolvers for Each Group for Each Problem inExperiment 6



Test phaseFirst similar text

problemNumber of nonsolversSecond similar text

problemNumber of nonsolversFirst transfer text

problemNumber of nonsolversSecond transfer text

problemNumber of nonsolvers

Group

Auditory-Auditory

55.00144.20

555.0079.302

44.600

60.402

170.408

158.706

Visual-Visual

55.0093.60

055.0051.30

1

43.100

35.900

170.108

152.408



be applied directly to the cognitive load consequences ofsplit attention. If students are required to split their attentionamong multiple sources of information that must be men-tally integrated before they can be understood, learning maybe inhibited because the act of mental integration requiresworking memory resources that consequently are unavail-able for schema acquisition and automation. Alternatively,if effective working memory can be increased by havingtwo sources of information presented via different modali-ties, the negative effects of split attention may be amelio-rated. This hypothesis was tested in this article.

In Experiments 1 and 2, we compared the conse-quences of presenting students with geometry workedexamples in which the statements accompanying the di-agram were presented in written mode, in auditory mode,or in both modes. Learning was comparatively enhancedby the auditory mode of presentation in both experi-ments, thus supporting the suggestion that working mem-ory capacity was increased by a dual-presentation mode.In Experiments 3 and 4, we tested the possibility that thesuperiority of the mixed mode of presentation was due tothe fact that auditory statements can be processed simul-taneously with the diagram, whereas written statementshave to be held in memory while attention is switchedfrom the statements to the diagram. In both experiments,results indicated that the mixed mode of presentation wassuperior even when both groups were forced to hold theinformation contained in the statements in working mem-ory before sighting the diagram. In Experiment 5, wetested the hypothesis that a modality effect could beobtained even when both sources of information con-sisted of statements rather than a diagram and statements.A mixed mode of presentation proved superior irrespec-tive of whether information concerning the dimensions ofa rectangle was presented in diagrammatic or writtenstatement form. Experiment 6 provided evidence that theresults of the previous experiments were unlikely to bedue to students simply finding listening an easier taskthan visually based processes such as reading. Therewere few differences between a group required to listento information as opposed to a group reading the samematerial. Minor differences that were obtained favoredthe reading group.

It is doubtful that reading skills reflect a significant factorin the results of these experiments. The number of wordsthat required reading was minimal. Furthermore, when read-ing, students could read the material as many times as theywished and, in Experiments 1 and 3, for as long as theywished. We might expect that any reading slowness or otherminor difficulties should be overcome with multiple read-ings. In contrast, the auditory groups only were able to hearthe material twice.

It also should be noted that the positive effects of avisual-auditory over a visual-visual mode of presentationextended to transfer problems as well as to problems similarto those used in the acquisition phase. Although our proce-dure of using multiple replications with small samples re-sulted in only some of the transfer comparisons yieldingsignificant effects, all of the differences in Experiments 1-5

favored the visual-auditory mode of presentation (see Ta-bles 1-5). We conclude that the visual-auditory presenta-tion of the information may have had the potential to permita deeper understanding of the material being studied thandid the visual-visual presentation modes, assuming thatspeed of solving transfer problem is indicative of depth ofunderstanding.

The materials used in the experiments required coor-dination between auditory and visual components. Coor-dination between components can be assumed to be gov-erned by the central executive (Baddeley, 1992), whichhas been the subject of recent research. Logie, Gilhooly,and Wynn (1994) found evidence that disruption of thecentral executive could severely disrupt working memoryperformance. Yee, Hunt, and Pellegrino (1991) foundevidence that the ability to coordinate perceptual andverbal information, which is a central executive function,was distinct from perceptual and verbal performancealone. If coordinating perceptual and visual informationrequires a central executive function that can be readilydisrupted, it could be argued that the visual-auditorygroups in the present experiments should perform worsethan the visual-visual groups, rather than better. In fact,coordination of the diagrammatic and verbal informationis just as important irrespective of the presentation mo-dality of the verbal information. The diagram and state-ments must be coordinated before a worked example canbe understood irrespective of whether the statements arepresented visually or aurally. If so, the act of coordina-tion should make equal demands of the central executiveunder both presentation modes. Our suggestion is thatmore working memory resources are available for coor-dination when a dual-presentation mode is used becausemore information is likely to be held in both auditory andvisual working memory rather than in just one.

As indicated earlier, the experiments were generated by acombination of cognitive load theory and recent theoriesand findings concerning basic working memory processes.In turn, that the results accord with the hypotheses strength-ens the theories that generated the hypotheses. Specifically,we see these results as supporting the suggestion that (a)consideration of limited working memory is a major deter-minant of instructional design success, and (b) workingmemory capacity can be increased with a dual-presentationmode.

Although the results are consistent with cognitive loadtheory, we have not attempted to measure cognitive loaddirectly. Our primary aim was to use the theory to generateexperiments providing direct instructional implications. Webelieve our experiments have succeeded in this aim. Nev-ertheless, the possibility of plausible alternative explana-tions of our results should not be discounted. Further workcould include subjective measures of cognitive load andefficiency measures of instructional conditions such asthose introduced recently by Paas and Van Merrienboer(1993, 1994).

There now is considerable work demonstrating theimportance of cognitive load in instructional design andthe presentation of information in general (e.g., Carroll,


1994; Paas, 1992; Paas & Van Merrienboer, 1994; Pierce,Duncan, Gholson, Ray, & Kamhi, 1993; Robins &Mayer, 1993; Trafton & Reiser, 1993; Van Merrienboer& De Croock, 1992). This work covers various proce-dures and materials and, we believe, suggests that in-structional design that does not emphasize cognitive loadfactors is likely to be deficient. The current work isintended as an extension of cognitive load factors ininstructional design. It differs in that whereas previousresearchers considered techniques designed to reduceextraneous cognitive load, we also considered techniquesfor increasing effective working memory. Both proce-dures can be highly effective.

In the current series of experiments, we have obtainedresults suggesting that when students must split their atten-tion between multiple sources of information that requiremental integration, cognitive resources available for learn-ing can be increased by presenting some of the verbalmaterial in auditory rather than written form. Frequently, ofcourse, it is not possible to present material in an auditorymode. Under these conditions, split attention can be reducedby physically integrating disparate sources of information(e.g., see Chandler & Sweller, 1991; Sweller et al., 1990).Nevertheless, the availability of computer-based educa-tional technology that can handle auditory material hasincreased markedly in recent years. Our results providetheoretically motivated and empirically tested techniquesfor the use of this technology. In more general terms,we believe that cognitive load theory can provide a usefulguide to instructional design under an increasing number ofcircumstances.

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