MAYER AND MORENOWAYS TO REDUCE COGNITIVE LOAD
Nine Ways to Reduce Cognitive Load in Multimedia Learning
Richard E. Mayer
Department of Psychology
University of California, Santa Barbara
Educational Psychology Program
University of New Mexico
separate systems for processing pictorial and verbal material (dual-channel assumption), each
channel is limited in the amount of material that can be processed at one time (limited-capacity
assumption), and meaningful learning involves cognitive processing including building con-
nections between pictorial and verbal representations (active-processing assumption). Second,
basedonthecognitivetheoryofmultimedialearning,weexaminetheconcept of cognitive over-
loadin which the learner’sintended cognitive processing exceedsthe learner’s available cogni-
tive capacity. Third, we examine five overload scenarios. For each overload scenario, we offer
one or two theory-based suggestions for reducing cognitive load, and we summarize our re-
search results aimed at testing the effectiveness of each suggestion. Overall, our analysis shows
that cognitive load is a central consideration in the design of multimedia instruction.
WHAT IS MULTIMEDIA LEARNING AND
The goal of our research is to figure out how to use words and
pictures to foster meaningful learning. We define multimedia
learning as learning from words and pictures, and we define
multimedia instruction as presenting words and pictures that
areintendedto foster learning. The wordscanbe printed (e.g.,
on-screen text) or spoken (e.g., narration). The pictures can
bestatic(e.g.,illustrations, graphs, charts, photos, or maps)or
dynamic (e.g., animation, video, or interactive illustrations).
An important example of multimedia instruction is a com-
puter-based narrated animation that explains how a causal
system works (e.g., how pumps work, how a car’s braking
systemworks, how the humanrespiratory system works,how
lightning storms develop, how airplanes achieve lift, or how
We define meaningful learning as deep understanding of
thematerial, which includesattending to importantaspects of
the presented material, mentally organizing it into a coherent
cognitive structure, and integrating it with relevant existing
knowledge. Meaningful learning is reflected in the ability to
applywhatwastaught to new situations, sowemeasurelearn-
ing outcomes by using problem-solving transfer tests (Mayer
& Wittrock, 1996). In our research, meaningful learning in-
volves the construction of a mental model of how a causal
system works. In addition to asking whether learners can re-
call what was presented in a lesson (i.e., retention test), we
also ask them to solve novel problems using the presented
material(i.e.,transfer test). All theresultsreportedin this arti-
cle are based on problem-solving transfer performance.
In pursuing our research on multimedia learning, we have
repeatedly faced the challenge of cognitive load: Meaningful
learning requires that the learner engage in substantial cogni-
tive processing during learning, but the learner’s capacity for
cognitiveprocessingisseverely limited. Instructional design-
ers have come to recognize the need for multimedia instruc-
tion that is sensitive to cognitive load (Clark, 1999; Sweller,
1999;van Merriënboer, 1997). A centralchallenge facing de-
signersofmultimediainstruction is the potential forcognitive
overload—inwhich the learner’s intended cognitiveprocess-
ing exceeds the learner’s available cognitive capacity. In this
articlewe present a theoryofhow people learnfrommultime-
dia instruction, which highlights the potential for cognitive
overload. Then, we describe how to design multimedia in-
EDUCATIONAL PSYCHOLOGIST, 38(1), 43–52
Copyright © 2003, Lawrence Erlbaum Associates, Inc.
Requests for reprints should be sent to Richard E. Mayer, Department of
Psychology, University of California, Santa Barbara, CA 93106–9660.
struction in ways that reduce the chances of cognitive over-
load in each of five overload scenarios.
HOW THE MIND WORKS
We begin with three assumptions about how the human mind
worksbased on researchin cognitive science—the dualchan-
nel assumption, the limited capacity assumption, and the ac-
tive processing assumption. These assumptions are summa-
rized in Table 1.
First, the human information-processing system consists
of two separate channels—an auditory/verbal channel for
processingauditory input andverbal representations and avi-
sual/pictorial channel for processing visual input and picto-
rial representations.1The dual-channel assumption is a
central feature of Paivio’s (1986) dual-coding theory and
Baddeley’s (1998) theory of working memory, although all
theorists do not characterize the subsystems exactly the same
way (Mayer, 2001).
Second, each channel in the human information-process-
ing system has limited capacity—only a limited amount of
cognitive processing can take place in the verbal channel at
anyone time, andonly a limitedamount of cognitiveprocess-
ingcantakeplace in the visual channelatanyonetime. This is
the central assumption of Chandler and Sweller’s (1991;
Sweller, 1999) cognitive load theory and Baddeley’s (1998)
working memory theory.
Third, meaningful learning requires a substantial amount
of cognitive processing to take place in the verbal and visual
channels. This is the central assumption of Wittrock’s (1989)
generative-learning theory and Mayer’s (1999, 2002) select-
ing–organizing–integrating theory of active learning. These
processes include paying attention to the presented material,
mentally organizing the presented material into a coherent
structure,and integrating thepresented material withexisting
Let us explore these three assumptions within the context
of a cognitive theory of multimedia learning that is summa-
rized in Figure 1. The theory is represented as a series of
boxes arranged into two rows and five columns, along with
arrows connecting them. The two rows represent the two in-
formation-processing channels, with the auditory/verbal
channelon top andthe visual/pictorial channelon the bottom.
Thisaspect of theFigure 1 is consistent with the dual-channel
The five columns in Figure 1 represent the modes of
knowledge representation—physical representations (e.g.,
words or pictures that are presented to the learner), sensory
representations (in the ears or eyes of the learner), shallow
working memory representations (e.g., sounds or images at-
tended to by the learner), deep working memory representa-
tions (e.g., verbal and pictorial models constructed by the
learner), and long-term memory representations (e.g., the
learner’s relevant prior knowledge). The capacity for physi-
callypresentingwords and pictures isvirtuallyunlimited,and
the capacity for storing knowledge in long-term memory is
virtually unlimited, but the capacity for mentally holding and
manipulating words and images in working memory is lim-
ited. Thus, the working memory columns in Figure 1 are sub-
ject to the limited-capacity assumption.
The arrows represent cognitive processing. The arrow
fromwordstoeyes represents printed wordsimpingingonthe
eyes; the arrow from words to ears represents spoken words
impinging on the ears; and the arrow from pictures to eyes
represents pictures (e.g., illustrations, charts, photos, anima-
tions, and videos) impinging on the eyes. The arrow labeled
selecting words represents the learner’s paying attention to
some of the auditory sensations coming in from the ears,
whereas the arrow labeled selecting images represents the
learner’s paying attention to some of the visual sensations
coming in through the eyes.2The arrow labeled organizing
words represents the learner’s constructing a coherent verbal
representation from the incoming words, whereas the arrow
labeled organizing images represents the learner’s construct-
ing a coherent pictorial representation from the incoming im-
ages. Finally, the arrow labeled integrating represents the
mergingoftheverbal model, the pictorialmodel,andrelevant
prior knowledge. In addition, we propose that the selecting
44 MAYER AND MORENO
1Based on research on discourse processing (Graesser, Millis, & Zwaan,
1997),itisnotappropriatetoequateaverbalchannelwithan auditory channel.
Mayer(2001)providedan extended discussion ofthenatureofdual channels.
Three Assumptions About How the Mind Works in Multimedia
Dual channel Humans possess separate information processing
channels for verbal and visual material.
Limited capacity There is only a limited amount of processing capac-
ity available in the verbal and visual channels.
Active processing Learning requires substantial cognitive processing
in the verbal and visual channels.
FIGURE 1 Cognitive theory of multimedia learning.
2Selecting words refers to selecting aspects of the text information rather
thanonlyspecificwords.Selecting images referstoselectingpartsof pictures
rather than only whole pictures.
and organizing processes may be guided partially by prior
knowledge activated by the learner. In multimedia learning,
active processing requires five cognitive processes: selecting
words, selecting images, organizing words, organizing im-
ages, and integrating. Consistent with the active-processing
assumption, these processes place demands on the cognitive
capacity of the information-processing system. Thus, the la-
beled arrows in Figure 1 represent the active processing re-
quired for multimedia learning.
THE CASE OF COGNITIVE OVERLOAD
Let us consider what happens in multimedia learning, that
is, a learning situation in which words and pictures are pre-
sented. A potential problem is that the processing demands
evoked by the learning task may exceed the processing ca-
pacity of the cognitive system—a situation we call cogni-
tive overload. The ever-present potential for cognitive
overload is a central challenge for instructors (including in-
structional designers) and learners (including multimedia
learners); meaningful learning often requires substantial
cognitive processing using a cognitive system that has se-
vere limits on cognitive processing.
We distinguish among three kinds of cognitive demands:
essential processing, incidental processing, and representa-
tional holding.3Essential processing refers to cognitive pro-
cesses that are required for making sense of the presented
material, such as the five core processes in the cognitive the-
ory of multimedia learning—selecting words, selecting im-
ages, organizing words, organizing images, and integrating.
For example, in a narrated animation presented at a fast pace
andconsisting of unfamiliar material,essential processing in-
volves using a great deal of cognitive capacity in selecting,
organizing, and integrating the words and the images.
Incidentalprocessingrefersto cognitive processes thatare
not required for making sense of the presented material but
are primed by the design of the learning task. For example,
adding background music to a narrated animation may in-
crease the amount of incidental processing to the extent that
the learner devotes some cognitive capacity to processing the
Representational holding refers to cognitive processes
aimed at holding a mental representation in working memory
over a period of time. For example, suppose that an illustra-
tion is presented in one window and a verbal description of it
is presented in another window, but only one window can ap-
pear on the screen at one time. In this case, the learner must
hold a representation of the illustration in working memory
while reading the verbal description or must hold a represen-
tation of the verbal information in working memory while
viewing the illustration.
Table 2 summarizes the three kinds of cognitive-process-
ing demands in multimedia learning. The total processing in-
tended for learning consists of essential processing plus
incidental processing plus representational holding. Cogni-
tive overload occurs when the total intended processing ex-
ceeds the learner’s cognitive capacity.4Reducing cognitive
loadcan involve redistributingessential processing, reducing
incidental processing, or reducing representational holding.
In the following sections, we explore nine ways to reduce
cognitive load in multimedia learning. We describe five dif-
ferent scenarios involving cognitive overload in multimedia
learning.For eachoverload scenario we offer one or two sug-
gestionsregardinghowto reduce cognitive overloadbasedon
effectiveness of our suggestions based on a 12-year program
of research carried out at the University of California, Santa
Barbara (UCSB). Our recommendations for reducing cogni-
tive load in multimedia learning are summarized in Table 3.
Type 1 Overload: Off-Loading When One
Channel is Overloaded With Essential
Problem: One channel is overloaded with essential
Consider the following situation:
A student is interested in understanding how lightning works.
She goes to a multimedia encyclopedia and clicks on the entry
for lightning. On the screen appears a 2-min animation depict-
ing the steps in lightning formation along with concurrent
on-screen text describing the steps in lightning formation. The
on-screentextis presented at thebottomon the screen, so while
thestudent is readingshe cannot view theanimation, and while
she is viewing the animation she cannot read the text.
This situation creates what Sweller (1999) called a
split-attention effect because the learner’s visual attention is
split between viewing the animation and reading the
WAYS TO REDUCE COGNITIVE LOAD 45
3Essentialprocessingcorrespondstothetermgermaneloadasused in the
introduction to this special issue. Incidental processing corresponds to the
representational holding is roughly equivalent to the term intrinsic load.
4To maintain conceptual clarity, we use the term processing demands to
referto properties of the learning materials or situation and the term process-
ing to refer to internal cognitive activity of learners.
Three Kinds of Demands for Cognitive Processing in Multimedia
Type of Processing Definition
Essential processing Aimed at making sense of the presented ma-
terial including selecting, organizing, and
integrating words and selecting, organiz-
ing, and integrating images.
Incidental processing Aimed at nonessential aspects of the pre-
Representational holding Aimed at holding verbal or visual represen-
tations in working memory.
on-screen text. This problem is represented in Figure 1 by the
arrow from picture to eyes (for the animation) and the arrow
from words to eyes (for the on-screen text); thus, the eyes re-
ceivealotof concurrent information, butonlysomeof that in-
formation can be selected for further processing in visual
workingmemory(i.e.,the arrow from eyes toimagescanonly
carry a limited amount of information).
One solution to this problem is
to present words as narration. In this way, the words are pro-
cessed—at least initially—in the verbal channel (indicated by
the arrow from words to ears in Figure 1), whereas the anima-
tion is processed in the visual channel (indicated by the arrow
from picture to eyes in Figure 1). The processing demands on
the visual channel are thereby reduced, so the learner is better
able to select important aspects of animation for further pro-
cessing (indicated by the arrow from eyes to image). The pro-
cessing demands on the verbal channel are also moderate, so
thelearnerisbetter able to select importantaspectsofthenarra-
tion for further processing (indicated by the arrow from ears to
sounds). In short, the use of narrated animation represents a
methodfor off-loading (orreassigning) some ofthe processing
demands from the visual channel to the verbal channel.
In a series of six studies carried out in our laboratory at
UCSB,students performed betteron tests ofproblem-solving
transfer when scientific explanations were presented as ani-
mation and narration rather than as animation and on-screen
text (Mayer & Moreno, 1998, Experiments 1 and 2; Moreno
& Mayer, 1999, Experiments 1 and 2; Moreno, Mayer,
Spires,& Lester, 2001, Experiments 4 and 5).The median ef-
fect size was 1.17. We refer to this result as a modality effect:
Students understand a multimedia explanation better when
the words are presented as narration rather than as on-screen
text. A similar effect was reported by Mousavi, Low, and
Sweller (1995) in a book-based multimedia environment.
46 MAYER AND MORENO
Load-Reduction Methods for Five Overload Scenarios in Multimedia Instruction
Type of Overload Scenario Load-Reducing Method Description of Research Effect Effect Size
Type 1: Essential processing in visual channel > cognitive capacity of visual channel
Visual channel is overloaded by
essential processing demands. Off-loading: Move some essential
processing from visual channel to
Modality effect: Better transfer when words
are presented as narration rather than as
Type 2: Essential processing (in both channels) > cognitive capacity
Both channels are overloaded by
essential processing demands. Segmenting: Allow time between
successive bite-size segments. Segmentation effect: Better transfer when
lesson is presented in learner-controlled
segments rather than as continuous unit.
Pretraining: Provide pretraining in
names and characteristics of com-
Pretraining effect: Better transfer when stu-
dents know names and behaviors of sys-
Type 3: Essential processing + incidental processing (caused by extraneous material) > cognitive capacity
One or both channels overloaded by
essential and incidental processing
(attributable to extraneous material).
Weeding: Eliminate interesting but
extraneous material to reduce pro-
cessing of extraneous material.
Coherence effect: Better transfer when ex-
traneous material is excluded. 0.90 (5)
Signaling: Provide cues for how to
process the material to reduce
processing of extraneous material.
Signaling effect: Better transfer when sig-
nals are included. 0.74 (1)
Type 4: Essential processing + incidental processing (caused by confusing presentation) > cognitive capacity
One or both channels overloaded by
essential and incidental processing
(attributable to confusing presenta-
tion of essential material).
Aligning: Place printed words near
corresponding parts of graphics to
reduce need for visual scanning.
Spatial contiguity effect: Better transfer
when printed words are placed near cor-
responding parts of graphics.
Eliminating redundancy: Avoid pre-
senting identical streams of
printed and spoken words.
Redundancy effect: Better transfer when
words are presented as narration rather
narration and on-screen text.
Type 5: Essential processing + representational holding > cognitive capacity
One or both channels overloaded by
essential processing and representa-
Synchronizing: Present narration
and corresponding animation si-
multaneously to minimize need to
hold representations in memory.
Temporal contiguity effect: Better transfer
when corresponding animation and nar-
ration are presented simultaneously
rather than successively.
Individualizing: Make sure learners
possess skill at holding mental
Spatial ability effect: High spatial learners
benefit more from well-designed instruc-
tion than do low spatial learners.
Note. Numbers in parentheses indicate number of experiments on which effect size was based.
The robustness of the modality effect provides strong evi-
dence for the viability of off-loading as a method of reducing
Type 2 Overload: Segmenting and
Pretraining When Both Channels are
Overloaded With Essential Processing
Demands in Working Memory
Problem: Both channels are overloaded with
essential processing demands.
Suppose a student
views a narrated animation that explains the process of light-
ning formation based on the strategies discussed in the previ-
oussection.In this case, someofthenarration is selected tobe
processed as words in the verbal channel and some of the ani-
mation is selected to be processed as images in the visual
channel (as shown by the arrows in Figure 1 labeled selecting
wordsandselectingimages,respectively). However, if the in-
formation content is rich and the pace of presentation is fast,
learners may not have enough time to engage in the deeper
processes of organizing the words into a verbal model, orga-
nizing the images into a visual model, and integrating the
models (as shown by the organizing words,organizing im-
ages, and integrating arrows in Figure 1). By the time the
learner selects relevant words and pictures from one segment
of the presentation, the next segment begins, thereby cutting
short the time needed for deeper processing.
This situation leads to cognitive overload in which avail-
able cognitive capacity is not sufficient to meet the required
processing demands. Sweller (1999) referred to this situation
asonein which thepresentedmaterial has high-intrinsic load;
that is, the material is conceptually complex. Although it
might not be possible to simplify the presented material, it is
possibletoallow learners todigestintellectually one chunk of
it before moving on to the next.
A potential solution to this
problem is to allow some time between successive segments
of the presentation. In segmenting, the presentation is broken
down into bite-size segments. The learner is able to select
words and select images from the segment; the learner also
has time and capacity to organize and integrate the selected
words and images. Then, the learner is ready for the next seg-
ment, and so on. In contrast, when the narrated animation is
presented continuously—without time breaks between seg-
ments—the learner can select words and select images from
the first segment; but, before the learner is able to complete
the additional processes of organizing and integration, the
nextsegmentispresented,which demands the learner’s atten-
tion for selecting words and images.
For example, Mayer and Chandler (2001, Experiment 2)
broke a narrated animation explaining lightning formation
into 16 segments. Each segment contained one or two sen-
tences of narration and approximately 8 to 10 sec of anima-
tion. After each segment was presented, the learner could
start the next segment by clicking on a button labeled CON-
TINUE. Although students in both groups received identical
material, the segmented group had more study time. Students
whoreceivedthesegmented presentation performed better on
subsequent tests of problem-solving transfer than did stu-
dentswho received a continuous presentation. The effectsize
in the one study we conducted was 1.36. We refer to this as a
segmentation effect: Students understand a multimedia ex-
planation better when it is presented in learner-controlled
segmentsrather than asa continuous presentation.Further re-
searchis needed todetermine the separate effectsof segment-
ing and interactivity, such as comparing how students learn
from multimedia presentations that contain built-in or
user-controlled breaks after each segment.
Although segmenting appears
to be a promising technique for reducing cognitive load,
sometimes segmenting might not be feasible. An alternative
techniquefor reducing cognitive loadwhen both channelsare
overloaded with essential processing demands is pretraining,
in which learners receive prior instruction concerning the
componentsin the to-be-learned system.Constructing a men-
tal model involves two steps—building component models
(i.e., representations of how each component works) and
building a causal model (i.e., a representation of how a
change in one part of the system causes a change in another
part,etc.). In processing a narrated animation explaininghow
a car’s braking system works, learners must simultaneously
build component models (concerning how a piston can move
forward and back, how a brake shoe can move forward or
back, etc.) and a causal model (when the piston moves for-
ward, brake fluid is compressed, etc.). By providing
pretraining about the components, learners can more effec-
tivelyprocessa narrated animation—devoting theircognitive
processing to building a causal model. Without pretraining,
students must try to understand each component and the
causal links between them—a task that can easily overload
In a series of three studies involving narrated animations
about how brakes work and how pumps work, students per-
formedbetter on problem-solving transfer testswhen the nar-
ratedanimation was preceded by a short pretraining aboutthe
names and behavior of the components (Mayer, Mathias, &
Wetzell, 2002, Experiments 1, 2, and 3). The median effect
size comparing the pretrained and nonpretrained groups was
1.00. Similar results were reported by Pollock, Chandler, and
Sweller (2002). We refer to this result as a pretraining effect:
Students understand a multimedia presentation better when
they know the names and behaviors of the components in the
system.Pretraining involves a specificsequencingstrategy in
which components are presented before a causal system is
WAYS TO REDUCE COGNITIVE LOAD 47
presented. The results provide support for pretraining as a
useful method of reducing cognitive load.
Type 3 Overload: Weeding and Signaling
When the System is Overloaded by
Incidental Processing Demands Due to
Problem: One or both channels are overloaded by
the combination of essential and incidental processing
In the two foregoing scenarios, the cognitive
system was required to engage in too much essential process-
ing—such as when complex material is presented at a fast
rate. Let us consider a somewhat different overload scenario
in which a learner seeks to engage in both essential and inci-
dental processing, which together exceed the learner’s avail-
ablecognitivecapacity.For example, suppose a learnerclicks
on the entry for lightning in a multimedia encyclopedia, and
heor she receivesa narrated animation describing thesteps in
lightning formation (which requires essential processing)
along with background music or inserted narrated video clips
of damage caused by lightning (which requires incidental
According to the cognitive theory of multimedia learning,
adding interesting but extraneous5material to a narrated ani-
mation may cause the learner to use limited cognitive re-
sources on incidental processing, leaving less cognitive
capacity for essential processing. As a result, the learner will
belesslikely to engageinthe cognitive processes requiredfor
meaningful learning of how lightning works—indicated by
thearrows in Figure 1. Sweller(1999) referred to the addition
of extraneous material in an instructional presentation as an
example of extraneous load.
Tosolvethis problem, we suggest
eliminating interesting but extraneous material—a load-re-
ducing technique can be called weeding. Weeding involves
making the narrated animation as concise and coherent as
possible, so the learner will not be primed to engage in inci-
dentalprocessing.Ina concise narrated animation, thelearner
is primed to engage in essential processing. In contrast, in an
embellished narrated animation—such as one containing
background music or inserted narrated video of lightning
damage—the learner is primed to engage in both essential
and incidental processing.
In a series of five studies carried out in our laboratory at
UCSB, students performed better on problem-solving trans-
fer tests after receiving a concise narrated animation than an
embellished narrated animation (Mayer, Heiser, & Lonn,
2001, Experiments 1, 3, and 4; Moreno & Mayer, 2000, Ex-
periments 1 and 2). The added material in the embellished
narrated animation consisted of background music or add-
ing short narrated video clips showing irrelevant material.
The median effect size was .90. We refer to this result as a
coherence effect: Students understand a multimedia expla-
nation better when interesting but extraneous material is ex-
cluded rather than included. The robustness of the
coherence effect provides strong evidence for the viability
of weeding as a method for reducing cognitive load.
Weedingseemsto help facilitate theprocessof selecting rel-
When it is not feasible to remove
all the embellishments in a multimedia lesson, cognitive load
can be reduced by providing cues to the learner about how to
select and organize the material—a technique called signaling
(Lorch, 1989; Meyer, 1975). For example, Mautone and
Mayer(2001) constructed a 4-min narrated animation explain-
ing how airplanes achieve lift, which contained many extrane-
ous facts and somewhat confusing graphics. Thus, the learner
might engage in lots of incidental processing—by focusing on
nonessential facts or nonessential aspects of the graphics. A
signaledversion guided thelearner’s cognitive processes of(a)
selecting words by stressing key words in speech, (b) selecting
images by adding red and blue arrows to the animation, (c) or-
ganizing words by adding an outline and headings, and (d) or-
ganizingimages by addinga map showing which of three parts
of the lesson was being presented. In the one study we con-
ducted on signaling of a multimedia presentation (Mautone &
Mayer, 2001, Experiment 3), students who received the sig-
naled version of the narrated animation performed better on a
subsequent test of problem-solving transfer than did students
who received the unsignaled version. The effect size was .74.
Werefertothisresult as a signaling effect:Studentsunderstand
a multimedia presentation better when it contains signals con-
cerning how to process the material. Although there is a sub-
stantial amount of research literature on signaling of text in
printed passages (Lorch, 1989), Mautone and Mayer’s study
offers the first examination of signaling for narrated anima-
tions. Signaling seems to help in the process of selecting and
organizing relevant information.
Type 4 Overload: Aligning and Eliminating
Redundancy When the System is
Overloaded by Incidental Processing
Demands Attributable to How the Essential
Material is Presented
Problem: One or both channels are overloaded by
the combination of essential and incidental processing
The problem is the same in Type 3 and Type 4
overload—the learning task requires incidental process-
ing—butthecause of the problemis different. In Type3over-
48 MAYER AND MORENO
port the educational goal of the presentation.
load the source of the incidental processing is that extraneous
material is included in the presentation, but in Type 4 over-
load the source of the incidental processing is that the essen-
tial material is presented in a confusing way. For example,
Type 4 overload occurs when on-screen text is placed at the
bottom of the screen and the corresponding graphics are
placed toward the top of the screen.
Solution: Aligning words and pictures.
In Type 3
overload scenarios, incidental cognitive load was created by
adding extraneous material. Another way to create incidental
cognitiveloadis to misalign wordsandpictures on the screen,
such as presenting an animation in one window with concur-
rent on-screen text in another window elsewhere on the
screen. In this case—which we call a separated presenta-
tion—the learner must engage in a great deal of scanning to
figure out which part of the animation corresponds with the
words—creating what we call incidental processing.In
eye-movement studies, Hegarty and Just (1989) showed that
learners tend to read a portion of text and then look at the cor-
responding portion of the graphic. When the words are far
from the corresponding portion of the graphic, the learner is
required to use limited cognitive resources to visually scan
the graphic in search of the corresponding part of the picture.
The amount of incidental processing can be reduced by plac-
ing the text within the graphic, next to the elements it is de-
scribing. This form of presentation—which we call inte-
grated presentation—allows the learner to devote more
cognitive capacity to essential processing.
Consistent with this analysis, Moreno and Mayer (1999,
Experiment 1) found that students who learned from inte-
grated presentations (consisting of animation with integrated
on-screen text) performed better on a problem-solving trans-
fer test than did students who learned from separated presen-
tations (consisting of animation with separated on-screen
text). The effect size in this single study was .48. Similar ef-
fects have been found with text and illustrations in books
(Mayer, 2001). We refer to this result as a spatial contiguity
effect: Students understand a multimedia presentation better
whenprintedwordsareplaced near rather than farfromcorre-
sponding portions of the animation. Thus, spatial alignment
of words and pictures appears to be a valuable technique for
reducingcognitive load. As you can see, aligningis similar to
signaling in that it guides cognitive processing, eliminating
the need for incidental processing. Aligning differs from sig-
naling in that aligning applies to situations in which essential
wordsandpictures are separatedandsignaling applies to situ-
ations in which extraneous material is placed within the mul-
Solution: Eliminating redundancy.
of Type 4 overload occurs when a multimedia presentation
consists of simultaneous animation, narration, and on-screen
text. In this situation—which we call redundant presenta-
tion—the words are presented both as narration and simulta-
neously as on-screen text. However, the learner may devote
cognitive capacity to processing the on-screen text and recon-
ciling it with the narration—thus, priming incidental process-
ing that reduces the capacity to engage in essential processing.
In contrast, when the multimedia presentation consists of nar-
rated animation—which we call nonredundant presenta-
tion—thelearner is notprimed to engagein incidental process-
ing.Inaseries of three studies (Mayer etal.,2001,Experiments
1 and 2; Moreno & Mayer, 2002, Experiment 2) students who
learned from nonredundant presentations performed better on
problem-solvingtransfer tests thandid students who learned from
redundant presentations. The median effect size was .69, indicat-
ing that eliminating redundancy is a useful way to reduce cogni-
tive load. We refer to this result as a redundancy effect: Students
understand a multimedia presentation better when words are pre-
sentedas narration rather than asnarration and on-screentext. We
use the term redundancy effect in a more restricted sense than
Sweller (1999; Kalyuga, Ayres, Chandler, & Sweller, 2003). As
you can see, eliminating redundancy is similar to weeding in that
both involve cutting aspects of the multimedia presentation. They
differ in that weeding involves cutting interesting but irrelevant
material,whereas eliminating redundancyinvolves cutting an un-
needed duplication of essential material.
When no animation is presented, students learn better
from a presentation of concurrent narration and on-screen
text (i.e., verbal redundancy) than from a narration-only pre-
sentation (Moreno & Mayer, 2002, Experiments 1 and 3). An
explanation for this effect is that adding on-screen text does
not overload the visual channel because it does not have to
compete with the animation.
Type 5 Overload: Synchronizing and
Individualizing When the System is
Overloaded by the Need to Hold
Information in Working Memory
Problem: One or both channels are overloaded by
the combination of essential processing and
In the foregoing two sections,
cognitive overload occurred when the learner attempted to
engage in essential and incidental processing, and the solu-
tionwasto reduce incidental processingthroughweeding and
signaling (when extraneous material was included), or
through aligning words and pictures or reducing redundancy
(when the same essential material was presented in printed
and spoken formats). In the fifth and final overload scenario,
cognitive overload occurs when the learner attempts to en-
gage in both essential processing (i.e., selecting, organizing,
and integrating material that explains how the system works)
and representational holding (i.e., holding visual and/or ver-
WAYS TO REDUCE COGNITIVE LOAD 49
bal representations in working memory during the learning
For example, consider a situation in which a learner clicks
on the lightning entry in a multimedia encyclopedia. First, a
short narration is presented describing the steps in lightning
formation; next, a short animation is presented depicting the
steps in lightning formation. According to a cognitive theory
of multimedia learning, this successive presentation can in-
creasecognitiveload because thelearnermust hold the verbal
representation in working memory while the corresponding
animation is being presented. In this situation, cognitive ca-
pacitymust be usedto hold a representation in working mem-
ory, thus depleting the learner’s capacity for engaging in the
cognitiveprocessesofselecting,organizing, and integrating.
A straightforward solution
to the problem is to synchronize the presentation of corre-
sponding visual and auditory material. When presentation of
corresponding visual and auditory material is simultaneous,
there is no need to hold one representation in working mem-
ory until the other is presented. This situation minimizes cog-
nitive load. In contrast, when the presentation of correspond-
ing visual and auditory material is successive, there is a need
to hold one representation in one channel’s working memory
until the corresponding material is presented in the other
channel. The additional cognitive capacity used to hold the
representation in working memory can contribute to cogni-
For example, in a series of eight studies carried out in our
laboratory at UCSB (Mayer & Anderson, 1991, Experiments
1 and 2a; Mayer & Anderson, 1992, Experiments 1 and 2;
Mayer,Moreno, Boire, & Vagge, 1999,Experiments 1 and 2;
Mayer & Sims, 1994, Experiments 1 and 2), students per-
formed better on tests of problem-solving transfer when they
learnedfrom simultaneous presentations (i.e.,presenting cor-
responding animation and narration at the same time) than
from successive presentations (i.e., presenting the complete
animationbeforeorafterthe complete narration). The median
effect size was 1.30, indicating robust evidence for synchro-
nizing as a technique for reducing cognitive load. We refer to
a multimedia presentation better when animation and narra-
tion are presented simultaneously rather than successively.
Note that the temporal contiguity effect is eliminated
when the successive presentation is broken down into
bite-size segments that alternate between a few seconds of
narration and a few seconds of corresponding animation
(Mayer et al., 1999, Experiments 1 and 2; Moreno & Mayer,
2002,Experiment2). In this situation,workingmemoryis not
likely to become overloaded because only a small amount of
material is subject to representational holding.
not be possible, an alternative technique for reducing cogni-
tive load is to be sure that the learners possess skill in holding
mental representations in memory.6For example, high-spa-
tial ability involves the ability to hold and manipulate mental
images with a minimum of mental effort. Low-spatial learn-
ersmay not beable to take advantageof simultaneous presen-
tation because they must devote so much cognitive process-
ing to hold mental images. In contrast, high-spatial learners
are more likely to benefit from simultaneous presentation by
being able to carry out the essential cognitive processes re-
quired for meaningful learning. Consistent with this predic-
tion, Mayer and Sims (1994, Experiments 1 and 2) found that
high-spatial learners performed much better on prob-
lem-solving transfer tests from simultaneous presentation
thanfromsuccessivepresentation, whereas low-spatial learn-
ers performed at the same low level for both. Across two ex-
periments involving a narrated animation on how the human
respiratory system works, the median effect size was 1.13.
Werefer to thisinteraction as thespatial ability effect,and we
notethat individualization—matchinghigh-quality multime-
dia design with high-spatial learners—may be a useful tech-
nique for reducing cognitive load.
Meeting the Challenge of Designing
Instruction That Reduces Cognitive Load
Amajorchallengefor instructional designers is thatmeaning-
fullearning can require a heavy amount of essentialcognitive
processing, but the cognitive resources of the learner’s infor-
mation processing system are severely limited. Therefore,
multimedia instruction should be designed in ways that mini-
mize any unnecessary cognitive load. In this article we sum-
marized nine ways to reduce cognitive load, with each
load-reduction method keyed to an overload scenario.
Our research program—conducted at UCSB over the last
12years—convincesus that effective instructionaldesignde-
pends on sensitivity to cognitive load which, in turn, depends
onanunderstanding of how thehumanmind works. Inthisar-
ticle, we shared the fruits of 12 years of programmatic re-
searchat UCSB andrelated research, aimedat contributing to
cognitivetheory (i.e., understanding thenatureof multimedia
learning) and building an empirical database (i.e., re-
search-based principles of multimedia design).
We began with a cognitive theory of multime-
dialearningbased on threecoreprinciples from cognitive sci-
ence, which we labeled as dual channel, limited capacity, and
active processing (shown in Table 1). Based on the cognitive
theory of multimedia learning (shown in Figure 1), we de-
50 MAYER AND MORENO
6Individualization is not technically a design method for reducing cogni-
tiveloadbutrathera way to select individuallearnerswhoarecapableof ben-
efitting from a particular multimedia presentation.
rived predictions concerning various methods for reducing
cognitive load. In conducting dozens of controlled experi-
ments to test these predictions, we were able to refine the the-
ory and offer substantial empirical support. Thus, the seem-
ingly practical search for load-reducing methods of
multimedia instruction has contributed to theoretical ad-
vances in cognitive science—a well-supported theory of how
people learn from words and pictures. Overall, our approach
has been based on the idea that the best way to improve in-
struction is to begin with a research-based understanding of
how people learn.
Our search for theory-based principles of
instructional design led us to conduct dozens of well-con-
trolled experiments—thereby producing a substantial re-
searchbase(summarized in Table3).For each of ourrecom-
mendations for how to reduce cognitive load, we see the
need to conduct multiple experiments. In some cases when
we report only a single preliminary study (i.e., segmenting,
signaling, and aligning) more empirical research is needed.
Clear and replicated effects are the building blocks of both
theory and practice. Overall, our approach has been based
on the idea that the best way to understand how people learn
is to test theory-based predictions in the context of student
Additional research is needed on
the measurement of cognitive load (cf. Brüncken, Plass, &
Leutner, 2003; Paas, Tuovinen, Tabbers, & Van Gerven,
2003).In particular, weneed ways to gauge(a) cognitive load
experiencedbylearners,(b)the cognitive demands of instruc-
tional materials, and (c) the cognitive resources available to
individual learners. Although we hypothesize that our nine
recommendationsreduce cognitive load, itwouldbe useful to
have direct measures of cognitive load.
Inourresearch,concise narrated animation fostered mean-
ingful learning without creating cognitive overload. How-
ever, additional research is needed to examine situations in
which certain kinds of animation can overload the learner
(Schnotz, Boeckheler, & Grzondziel, 1999) and to determine
therole of individualdifferences in visual andverbal learning
stylesin influencingcognitive overload (Plass, Chun, Mayer,
& Leutner, 1998; Riding, 2001). In addition, it would be
worthwhile to examine whether the principles of multimedia
learning apply to the design of online courses that require
many hours of participation, to problem-based simulation
games, and to multimedia instruction that includes on-screen
pedagogical agents (Clark & Mayer, 2003).
In short, our program of research convinces us that the
search for load-reducing methods of instruction contributes
to cognitive theory and educational practice. Research on
multimedia learning promises to continue to be an exciting
venue for educational psychology.
This research was supported by Grant N00014–01–1–1039
from the Office of Naval Research.
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