A Unifying Framework for Defining and Measuring Physical and Cognitive Load Eric Jonesa, Sandra Stankovica, Caroline Harriotta, Al Sciarrettab,

Andrea Webba aDraper bCNS Technologies Inc.

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DARPA Squad X Core Technologies (SXCT)

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Seeking to bring unprecedented capability to dismounted U.S. Army and U.S. Marine Corps squads…

Source: DARPA Artist’s Concept

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Mission vs. Warfighter Impact

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…in part by implementing system-level changes to the squad architecture

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Two Contributions

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1. Framework: Defines human performance in terms of the physical and mental effort that are expended when accomplishing physical and mental tasks

2. “Load factors:” Define the impact of physical and cognitive load on the individual and on the mission

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Mental vs. Cognitive Workload

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Mental Workload ISO-10075-1: How hard a part or multiple parts of a person’s brain is working during performance of a task VACP Mental Workload (Mitchell, 2000):

• Visual: Stimuli seen • Auditory: Stimuli heard • Cognitive: “Thinking” • Psychomotor: Movement

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Human Performance Framework

Energy Capacity (Volume)

Effort (Rate of

Expenditure) Observe/ Perceive Visual Workload

Auditory Workload Haptic Workload

Resilience (Rate of

Replenishment)

Act Psychomotor Workload Physical Load Factors

Orient/ Decide Cognitive Load Factors

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Effort (Rate of

Expenditure)

Resilience (Rate of

Replenishment)

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Individual Differences Factors

Innate Characteristics Past and Recent Experiences

Energy Capacity (Volume)

Observe/ Perceive Visual Workload

Auditory Workload Haptic Workload

Act Psychomotor Workload Physical Load Factors

Orient/ Decide Cognitive Load Factors

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Physical Load

Strength

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Coordination

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Physical Load Factors Derivation

Stamina: Magnitude of physical work performed

Endurance: Duration of sustained physical effort

Strength: Amount of directed force Posture: Difference between desired and achieved

body position Coordination: Difference between desired and

achieved body position over time Speed: Linear and angular displacement over time Acceleration: Ability to change speed over time Agility: Ability to change velocity vector over time

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We often turn to mechanical analogies when non-mechanical systems exhibit behaviors that are analogous to mechanical systems

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Cognitive Load Factors Derivation

The Maxwell Analogy (1861) – electrical circuits represented as mechanical

systems

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Physical and Cognitive Load Factors

Physical Load Factors Definition

Cognitive Load Factors Definition

Stamina Magnitude of physical work

performed

Endurance Duration of sustained physical

effort

Strength Amount of directed force

Posture Difference between desired and

achieved body position

Coordination Difference between desired and

achieved body position over time

Speed Linear and angular displacement

over time

Acceleration Ability to change speed over

time

Agility Ability to change velocity vector

over time

Stamina Magnitude of cognitive work performed

Endurance Duration of sustained cognitive effort

Skill Ability to deal with complexity; ability to oppose cognitive stress

Mental Stability

Ability to regulate or maintain mental state

Sensemaking Accuracy of projection of future outcomes

Processing Rate

Number of cognitive processes over time

Cognitive Acceleration

Ability to achieve a level of performance when switching tasks

and/or states Cognitive

Agility Ability to incorporate and prioritize

new cognitive demands

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Future Work

Physical and cognitive load factor decomposition Interaction between physical and cognitive loads Cognitive load factor operationalization Applications to team performance assessment

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Final Thought

Not all defined, but recognizing an underlying structure to derive new insight

“Periodic Table” for Human Performance

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Thank you Eric Jones ejones@draper.com 617-258-1698 www.draper.com

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