Education Theory Made Practical – Volume 4, Part 6: Multiple Resource Theory

For the fourth year, we are collaborating with the ALiEM Faculty Incubator Program to serialize another volume of Educational Theory made Practical. The Faculty Incubator program a year-long professional development program for educators, which enrolls members into a small, 30-person, mentored digital community of practice (you can learn more here); and, as part of the program, teams of 2-3 participants author a primer on a key education theory, practically linking the abstract to practical scenarios.  

They have published their first and second e-book compendium of this blog series and you can find the Volume 3 posts here (the e-book is in progress!) As with the previous iterations, final versions of each primer will be complied into a free eBook to be shared with the health professions education community. 


Your Mission if you Choose to Accept it:

The ALiEM Faculty Incubator Program would like to invite you to peer review each post. Using your comments, they will refine each primer. No suggestion is too big or small – they want to know what was missed or misrepresented. Whether you notice a spelling or grammatical mistake, or want to suggest a preferred case scenario that better demonstrates the theory, they welcome all feedback! (Note: The blog posts themselves will remain unchanged.)

This is the sixth post of Volume 4!  You can find the previous posts here: Cognitive Load Theory; Epstein’s Mindful Practitioner; Joplin’s Five-stage Model of Experiential Learning; Maslow’s Hierarchy of Needs and Miller’s Pyramid.

Multiple Resource Theory

Authors: Matt Zuckerman (@matthew608b); Alison Hayward (@alisonation)

Main Authors or Originators: Christopher Wickens

Other important authors or works:

  • Daniel Kahneman

  • David Boles

  • David Strayer

Part 1: The Hook

Matt is an EM intern preparing for this week’s conference. He attempts to watch one of the suggested FOAMed videos about diabetic ketoacidosis (DKA) while washing the dishes and keeping an eye on his 12 month old daughter. He finished the video twice but each time he finds that he can’t remember anything. Matt feels frustrated because he knows that he’s attempting to do three things at once and doing them all poorly. Between his clinical responsibilities and trying to keep things going around the house, he rarely gets time alone to study. He’s worried that the only option is going to conference unprepared, neglecting his daughter, or switching to take out meals. He considers ponders his dilemma and realizes that the main issue isn’t necessarily needing more time, but figuring out some way to use that time more efficiently.

Part 2: The Meat


Multiple resource theory attempts to describe the demands placed on one operator performing multiple tasks simultaneously. Why is it easier to do some things simultaneously, while others interfere? Why do we turn down the radio when we’re lost in the car but not when we’re eating? The difference lies in how much processing each activity requires and whether they require similar resources. Tasks that require high levels of processing or similar resources (input channels, motor responses) will be done less efficiently simultaneously. Improved efficiency can be obtained by separating the overlap.

One example is pulse oximeters that warn of low oxygen levels or pulse rates with changing audio tones while an operator is looking at an airway and using muscle memory to place an endotracheal tube. Our brain localizes processing of different media to various areas (vision in the occiput, auditory processing in the temporal lobe). As such, we can monitor visual and auditory channels simultaneously without a serious degradation in efficiency. Researchers have demonstrated that brain lesions localized to the visual cortex vs the auditory cortex can have divergent effects on processing pictures vs sounds. The example of the pulse oximeter uses these divergent pathways to increase the amount of information we process simultaneously.

The degree of processing required (as a result of task complexity or operator experience) also has an effect on the example above. An experienced laryngoscopist notes a grade 3 view of the vocal cords and immediately adjusts the laryngoscope to improve to a grade 1 view. This muscle memory is gained through countless hours of consciously adjusting the laryngoscope to see whether raising or lowering the blade improves the view. Those same hours may be spent learning to drive. A student driver will have difficulty talking and driving simultaneously, but an experienced driver will have little difficulty. Alternatively, the experienced driver can safely listen to the radio but would be foolish to watch a movie while driving.

Christopher Wickens, the originator of multiple resource theory, lays out the principles that define multiple resource model architecture: demand, resource overlap, and allocation policy. These principles are used to change the characteristics of the particular activities that are being done simultaneously. These characteristics can include stages of processing (encoding inputs, processing them, responding), modalities (visual or auditory), responses (manual or vocal) or coding (spatial or verbal).1(See figure)


Christopher Wickens created the multiple resource theory model to explain why some tasks are easier to do simultaneously (walking and chewing gum) while others are much harder (talking and reading). He recognized that several different schools of thought were attempting to explain the same phenomenon in different ways.

Historical explanations of dual task performance relied on mechanical analogies of workload and power. Improvements in process required changes in torque and lubrication, such as in an engine. As electronic computers became more popular, the conception of learners having a central processor also became popular. Kahneman’s 1973 book, “Attention and Effort,” attempted to explain human performance using a general pool of mental “effort” without differentiated resources.2 Other scientists in the field (Isreal, Wickens, Chesney, & Donchin) had noted that resources seemed to be specialized, as the nature of simultaneous tasks affected our ability to do them. In an expansive review of the literature, Wickens attempted to reconcile these theories and integrate experimental literature.

Wickens posited that tasks compete for a shared pool of multiple resources. Simultaneous tasks that require similar resources may interfere with each other (e.g. reading a book while listening to another book). Performing two tasks simultaneously will usually reduce the efficiency of each task, however this effect is not the same for every task or every operator. To clarify, tasks are easier to perform and most efficient when done without competing demands. Even listening to music while driving requires some occasional moments when the driver is focused on the music to the exclusion of the road or is focussed on navigating and misses part of a song. Exceptions may include those who have undergone a callosotomy, allowing different areas of the brain to operate independently.

However, multiple resource theory recognizes that in reality we frequently must complete multiple tasks simultaneously. By understanding what types of tasks can be combined with the least drop in efficiency, we can improve outcomes.

In a particular multitasking scenario, the reduction in efficiency resulting from performing any given tasks simultaneously is thus known as task interference.3,4 This decrease in efficiency can vary depending on the difficulty of the tasks and whether they require overlapping resources. 1,5,6,7,8

Multiple resource theory model
Graphical representation of Wickens’ Multiple Resource Theory Model.
Drawn by KT Smith of HFE Solutions

Listening to music while writing a letter requires handling different modalities (visual and auditory) but these tasks share a central verbal processor for composing the letter and comprehending the lyrics. This task will be easier to accomplish than listening to an audio book while writing a letter because the cognitive demands for audio book comprehension are higher. An unfamiliar audiobook requires the listener to encode each word and sentence as it contributes to the character or plot. If the listener is distracted or not operating efficiently, he or she may miss key information and have to repeat a section. Whereas song lyrics are often familiar and have repetition and themes (rhyme, alliteration, shared vocabulary) that decrease processing loads. For example, “I heard it . . . the grapevine, not much longer would you be . . . “ is familiar and understandable even if it’s incomplete.

It is unclear if the idea of a shared pool of resources is reflected structurally in how the different parts of the brain handle different tasks. Regardless of whether the model is anatomically accurate, it is conceptually useful.

Modern takes or advances

The modern ubiquity of mobile phones increases the tendency to multitask as we constantly respond to texts or lookup information while driving, walking, or engaging in live meetings. This ubiquitous source of work and pleasure is an unanticipated driver of multitasking, not conceived of when Wickens wrote his paper in 1981.

Based on experimental testing of multiple resource theory, Boles has suggested adding tactile input as a separate modality of input apart from visual and auditory. For example, pilots that are focusing on a visual display and listening to audio instructions perform better with tactile warnings communicated with vibrations than with visual warnings. These researchers point out that tactile input is an underutilized modality in the design of safety alerts, which tend to rely heavily on visual attention.9 Boles additionally has differentiated the auditory and visual processing modalities, breaking auditory processing into linguistic and emotional components, and visual into positional spatial versus quantitative components, for example reviewing lab values in chart format instead of as a spreadsheet of numbers.10,11 The practical implications of this are that we can actually do much more much better if we can separate the input and processing channels and not only rely on visual sources of input.

A variable spectrum of effects on resource utilization described within the model has also been further elucidated. It has been observed, for example, that not all visual information can be considered equally interfering based on the distance in space of the sources of relevant information. If information must be gathered from sources that require only eye movements, for example, this would cause a lower level of visual interference than information that requires head movement to be acquired.8

Other examples of where this theory might apply in both the classroom & clinical setting

Other examples of where this theory might apply in both the classroom & clinical setting
This theory has important implications for medical education as learners are frequently asked to perform multiple tasks simultaneously. Consideration should be given to multiple resources theory when planning any lecture or workshop, in order to optimize the use of inputs while minimizing task interference for learners. For example, avoiding distracting music or lecture while learners are focusing on learning a manual task or procedural skill. This theory also supports the cognitive theory of multimedia education, as both address communicating information through different channels to avoid overload.

Multiple resource theory can also help explain the task efficiency learners gain when procedural tasks become more automatic and require less processing. The surgical intern who must focus solely on tying her knots well becomes the senior who can tie knots effortlessly while monitoring bleeding and case progression. It can also help explain why task switching and interruptions in the emergency department can affect efficiency and processing, or why the ED provider can passively monitor the ambient audio announcements of ambulance arrivals and nursing conversations and simultaneously visually review the CT scan on a trauma patient.

Modern high fidelity simulation design should factor these concepts in to simulations that require a provider to handle multiple patients at once or watch vital signs while EMS gives report attempts to reflect the demands that multiple resources place on a provider, to reflect real world scenarios in which interruptions in care are commonplace and help trainees to practice task management, task prioritization, and task scheduling which can help to minimize the effects of high demand situations, such as periodically “running the board.” Through these exercises and through practicing during “senior” shifts where residents practice acting as attending physicians, they can develop strategies to deal with the cognitive load and optimize multitasking abilities. Studies suggest, as might be expected, that high stress/high cognitive load situations with frequent interruptions may result in significant medical errors.12, 13, 14

The model also has important implications for clinical practice and contributes to how we present information on patient monitors and in electronic medical records, as well as alarms and when those processes break down (e.g. alarm fatigue). Design of safety related alerts must take into account that utilizing different resources will likely increase staff responsiveness to a potential error or problem. For example, some monitors utilize flashing lights, rather than just auditory stimuli, to indicate alerts. Using tactile vibrating phones that specifically alarm with a cardiac arrest could increase successful responses when compared to adding yet another beeping machine in the ED. Color coding labs or vital signs that are abnormal or providing the option of displaying values in a graphical format helps to highlight the abnormal values and increases likelihood of providers taking note and responding appropriately.

Annotated Bibliography of Key Papers

Processing Resources in Attention1: Christopher Wickens 1981.

Wickens’ seminal paper on multiple resources theory discusses historical views of the source of variance in time-sharing performance and the formulation of a “performance resources function” that describes the relationship between the quality of performance and the quantity of resources invested in a task. The applications of multiple resource theory are detailed in practice.

Multiple Resources and Performance Prediction7: Christopher Wickens 2001.

The theory is approached from the perspective of its predictions of task interference dependent on the modality used to complete a task or convey information. For example, whether reviewing a map while driving will affect the operation of the vehicle and whether placement of that map on a heads up display will modulate this interference. The multiple resource model is reviewed in great detail with regard to how the components of each dimension of the model may affect one another in either creating or avoiding task interference, thus affecting time-sharing ability, and, ultimately, performance.

Multiple Resources and Mental Workload8: Christopher Wickens 2008.

In this paper, Wickens details the origins of the multiple resource theory. He describes additional research done since his seminal paper on the subject and how it has bolstered as well as challenged the theory. He describes the related but distinct concept of mental workload, reporting that the multiple resource theory is most relevant to performance breakdowns related to dual-task overload. Multiple resource model architecture consists of three components demand, resource overlap, and allocation policy; whereas, mental workload focuses mainly on demand regardless of whether there are single or multiple tasks occuring.


The limitations of multiple resource theory include variability in measuring efficiency of tasks, as well as the challenge of estimating a ‘baseline’ level of demand for tasks, since the level of demand for a given task may be very reliant on the experience level of the individual in question with the task.15

The multiple resource model assumes that resources will be deployed logically and optimally towards each task being completed. More recent studies suggest that this may not be the case: there are tasks which are more engaging than others, such that they preempt other tasks. Studies have found that drivers became so engrossed by cell phone conversations that they failed to continue to pay attention to their surroundings, despite the fact that there is little overlap in resource allocation between the two tasks.3, 16, 17

There are often parallel suboptimal processes in medicine, for example, when emergency physicians working on a critical airway become distracted by a lower priority task (e.g. answering a call about a critical lab value which does not actually require any urgent response, like a markedly elevated BUN level in a dialysis patient). Further study is needed to elucidate how to identify and minimize these distractions.

Part 3: The Denouement

Matt realizes that he is struggling to process visual inputs from his FOAMed video while simultaneously looking at the dishes and his daughter. He instead finds an audio FOAMed resources on DKA that he listens to while singing to his daughter about DKA and washing the dishes. In this way he separates visual from auditory inputs and reduces mental load thinking about what his daughter is doing by entertaining her with a fun song. He also reinforces the material he is learning through simultaneous repetition. By the time he is done with the podcast, the dishes are clean, his daughter is ready for bed, and he is prepared for his conference small group on DKA.

Don’t miss the seventh post in the series, coming out Tuesday, March 24, 2020!



1. Wickens CD. Processing resources in attention. in Parasuraman R and Davies R, eds. Varieties of attention. New York, NY: Academic Press,1984.

2. Kahneman D. Attention and Effort. Englewood Cliffs, NJ: Prentice-Hall;1973.

3. Pashler, H. Dual Task Interference in Simple Tasks: Data and Theory. Psychological Bulletin. 116(2):220–244.

4. Wickens CD, Sandry D, & Vidulich, M. Compatibility & Resource Competition. Human Factors, 1983;25,227-248.

5. Wickens CD. Processing resources and attention. Multiple-task performance. Mar 2;1991:3-4.

6. Boles D. Multiple Resources. International Encyclopedia of Ergonomics and Human Factors, Vol 3.

7. Wickens CD. Multiple resources and performance prediction. Theoretical issues in ergonomics science. 2002 Jan 1;3(2):159-77.

8. Wickens CD. Multiple resources and mental workload. Human factors. 2008 Jun;50(3):449-55.

9. Sklar AE, Sarter NB. Good vibrations: Tactile Feedback in Support of Attention Allocation and Human-Automation Coordination in Event-Driven Domains. Human Factors. Human Factors. 1999 Dec 41(4),543–552.

10. Boles DB, Law MB. A simultaneous task comparison of differentiated and undifferentiated hemispheric resource theories. Journal of Experimental Psychology: Human Perception and Performance. 1998 Feb;24(1):204.

11. Boles DB. Lateralized spatial processes and their lexical implications. Neuropsychologia. 2002 Jan 1;40(12):2125-35.

12. Pawar S, Jacques T, et al. Evaluation of cognitive load and emotional states during multidisciplinary critical care simulation sessions. BMJ Simul Technol Enhanc Learn. 2018 Apr;4(2):87-91.

13. Li SY, Magrabi F, et al. A systematic review of the psychological literature on interruption and its patient safety implications. J Am Med Inform Assoc. 2012 Jan-Feb;19(1):6-12.

14. Ratwani RM, Fong A, et al. Emergency Physician Use of Cognitive Strategies to Manage Interruptions. Ann Emerg Med. 2017 Nov;70(5):683-687.

15. Wickens CD & Boles D. The Limits of Multiple Resource Theory. University of Illinois Engineering Psych. Lab Tech Report; Nov 1983.

16. Strayer DL, Drews FA. Cell-Phone–Induced Driver Distraction. Current Directions in Psychological Science, 2007;16(3),128–131.

17. Strayer DL, Johnston W. Driven to distraction: dual task studies of simulated driving and conversing on a cellular telephone. Psychological Science,12,462-466.

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