human factors psychology: strategies for anticipating and ... pollack.pdf · of hazards with common...

Safety of Consumer Products: Risk, Responsibility and Reputation

Cartagena de Indias, Colombia September 3-4, 2015

Carol Pollack-Nelson, Ph.D. Independent Safety Consulting 301-340-2912 [email protected]

Human Factors Psychology: Strategies for Anticipating

and Addressing Product Hazards

Human Factors Psychology

Seeks to understand & enhance interaction

between consumers and products


Objectives of a HF Analysis

• How will consumer use and respond to product? - Who are foreseeable users? - What are intended &

reasonable unintended uses? - What are reasons for

“misuse”; Can these be prevented?

• Identify hazardous components, procedures


Behavioral Task Analysis:

How will the product be used?


1. Assembly 2. Product use 3. Cleaning, Troubleshooting 4. How consumers leave product (e.g.,

disassembly, storage, turning product off)

Consider all Steps in Using a Product


Assembly: Instruction Manuals


Used as needed Stored in a drawer Consulted as needed

Consumers Assemble Products Intuitively


Guide Intuitive Assembly with Sensory Feedback

• Consumers rely on senses

to guide assembly

• Provide overlapping or redundant sensory cues, (especially if vision is limited)

• No erroneous or conflicting

cues


• If so, does this lead to a “critical” error? • Design components that should not be

interchanged so that they cannot be interchanged.

Are Components Interchangeable?


Are instructions easy to follow by intended user?

– Readability of text – Are all components

depicted & identified? – Do pictures & words

correspond? – Have instructions

reviewed by native speaker


#2 - Using the Product


Consumers Expectations & Hazard Awareness • They don’t expect major

surprises (hazards) • Consumers are often unaware

of hazards with common household products

• They expect product has been tested & is safe


Ensure Product Meets or Exceeds Mandatory & Voluntary Standards

• Standards are minimum requirements

• Compliance does NOT assure product is safe

- Limited number of standards - Written for a class of products - Developed as part of a consensual process • Develop internal standards - For specific product - Likely use behaviors

Consumers are Efficient

• They overtax products • Design products to

withstand reasonable abuse


Consumers Multi-Task

• May not watch product consistently for extended time

• Build prevention devices

into the product (e.g., automatic shut-off; whistle)


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Consumers Forget to Turn Things Off

• They get distracted; they fall asleep

• They think the product should be safe to stay on for a long time

• Built-in safety devices (auto shut-off;

timer)


Past Experiences Guide Behavior • Past experience with similar products

leads to expectations of how new product functions

• “Behavioral script”

• Potential problem: Familiar product that functions differently or has new interface

• New designs need to respect

consumer habits… or need to break the “script” by impeding old behaviors.


Children are Attracted to Adult Products

• Features that Appeal To

Children – Appears child-like, looks like

product intended for play – Has responsive features –

produce visual or auditory reaction

– Allows for imitation of adults – Sweet smells; looks like

candy • Utilize child-resistant

features


More Likely to Use Safety Equipment When It Is Included


• Perception: If the safety device is truly necessary, it would be included

• Extra cost

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#3 - Cleaning & Fixing Product


When Something Goes Wrong,

People Explore with their Fingers

• …Or they use whatever is

handy • No accessible sharp, moving

components, or “live” components


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• Is there a practical way to clean or fix the product?

• Are suitable cleaning

products specified; consumers use what is handy

More on Troubleshooting &

Cleaning


#4 - Disassembly & Storage


“Store Away From Children” • Consumer storage = out of child’s

reach + convenient, practical • Storing “out of reach” does not make

a product inaccessible • Common place for storage = the

garage, shed or storage room (where toys may also be stored)

• Child-resistant features protect best


Identifying Hazardous Components: Anthropometry Data

Anthropometry

The scientific study of the measurements and proportions of the human body

Types of Anthropometric Measurements

Static Anthropometry

• Measures body in standardized static postures – Stature (height) – Weight – Center of gravity – Body breadths, depths,

circumferences – Height of body landmarks from

floor – Seated height

Used to ensure product will fit the intended user

Avoid Entrapment Retention of fingers, hand, foot, & head in openings

• Dynamic measurements • Strength of arms, hands,

fingers, legs & mouth – Gross behaviors -

Pushing, pulling, lifting – Fine motor behaviors -

(wrist) twisting, pinching, gripping, squeezing, biting forces, lip strength

Strength Data

Strength Data - For inclusion

• Useful for determining if intended user will be able to open container or operate product

Exclusion - Preventing access and operability by unintended users

Factors to Consider When Applying Anthropometry Data

Be Aware of Human Variability

• Inconsistency within an age group

• Sex differences, puberty

• Inconsistency within a person’s body

• Cultural differences

• Subject – Posture for static

measurements of body dimensions

– Effort for dynamic measurements

• Tester – Directions given – Read-out of certain

devices

Potentially Confounding Factors

Addressing Product Hazards: Follow the Safety Hierarchy


First - Eliminate the Hazard


Second - Guard Against the Hazard:

Block Access


Guard Against Hazard: Auto Shut-Off


Last – Warn About the Hazard


Even Large and Conspicuous Warnings are often Overlooked


Consumers Don’t Notice Warnings on Familiar Products


High “Cost” Reduces Compliance


Warnings Cannot Overcome

Intuitive Use


Warnings Cannot Overcome Product Affordances

Warnings are not a substitute for safe design

Thank You


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