Human Factors Human Factors PsychologyPsychology

Lecture 1: Course Lecture 1: Course IntroductionIntroduction

PSY-4340/PSY-5340, Dr. William Langston, MTSU

Gas PumpGas Pump

How Do I Open This?How Do I Open This?

Some human factors issues to consider:Some human factors issues to consider: The goal of human factors is to optimize system The goal of human factors is to optimize system

performance (operator + machine + environment). A performance (operator + machine + environment). A 50% failure rate is hardly optimizing system 50% failure rate is hardly optimizing system performance.performance.

(Picture from Darnell, 2003).(Picture from Darnell, 2003).

Will’s RulesWill’s Rules

1.1. The proper way to use a device The proper way to use a device should be obvious from looking at should be obvious from looking at it.it.

2.2. Even in a reasonably trivial Even in a reasonably trivial situation like this, wasted time and situation like this, wasted time and effort are frustrating and effort are frustrating and unnecessary. If it really mattered unnecessary. If it really mattered (like in a car), serious disaster (like in a car), serious disaster could result.could result.

The Infamous BallotThe Infamous Ballot

Some human factors issues to consider:Some human factors issues to consider:The side-by-side presentation is confusing.The side-by-side presentation is confusing.No consideration of even minimal visual impairment.No consideration of even minimal visual impairment.No consideration of even minimal motor impairment.No consideration of even minimal motor impairment.Why is it possible to punch two if you can only vote for one?Why is it possible to punch two if you can only vote for one?It presents extraneous information (e.g., the numbers).It presents extraneous information (e.g., the numbers).

Will’s RulesWill’s Rules

1.1. You have to consider You have to consider everyevery potential user, not just young, tech-potential user, not just young, tech-savvy people with perfect vision.savvy people with perfect vision.

2.2. You have to You have to anticipateanticipate common common mistakes the user might make and mistakes the user might make and preventprevent those mistakes. those mistakes.

3.3. NothingNothing the user does should the user does should result in a catastrophic error. result in a catastrophic error. EverEver..

Popping the TrunkPopping the Trunk

Some human factors issues to consider:Some human factors issues to consider: Physical limitations also need to be considered Physical limitations also need to be considered

in design. When hiding controls, keep in mind in design. When hiding controls, keep in mind that fingers have less visual acuity than eyes.that fingers have less visual acuity than eyes.

(Picture from Darnell, 2003).(Picture from Darnell, 2003).

Will’s RulesWill’s Rules

1.1. You have to consider the everyday You have to consider the everyday use of an object when planning its use of an object when planning its design. Will it work as intended in design. Will it work as intended in the heat of the moment?the heat of the moment?

HubrisHubris * Customer: "I'm looking at the back of the system, and I don't

know where to plug in the mouse. There are two holes that are the same size as the mouse."

* Tech Support: "Ok, what color is the tip of the mouse plug?" * Customer: "Orange." * Tech Support: "Do you see the orange 'hole' on the back of the

computer?" * Customer: "Yes." * Tech Support: "That is where the mouse plugs into." * Customer: "Oh. How about the keyboard?" * Tech Support: "What color is the plug on the keyboard?" * Customer: "Purple." * Tech Support: "And do you see the purple 'hole' on the back of

the computer?" Etc.From Stoddard, S., & RinkWorks Productions. (2003). Computer

stupidities: Calls from Hell. Retrieved May 10, 2003 from http://www.rinkworks.com/stupid/.

You try…You try…

Does the green label go with the top or the Does the green label go with the top or the bottom hole? (Ignore the arrows, they’re bottom hole? (Ignore the arrows, they’re not intended to be giving the answer.)not intended to be giving the answer.)

(Picture from Darnell, 2003).(Picture from Darnell, 2003).

Will’s RulesWill’s Rules

1.1. Blaming the user is Blaming the user is notnot the same thing the same thing as proper human factors design.as proper human factors design.

2.2. It’s important to step back and think like It’s important to step back and think like a novice user, not a developer/designer. a novice user, not a developer/designer. Of course Of course youyou know how it works. know how it works.

Fundamental Attribution Fundamental Attribution ErrorError

When people make mistakes we tend to make When people make mistakes we tend to make an internal attribution. In other words, we an internal attribution. In other words, we perceive people’s mistakes as being their perceive people’s mistakes as being their fault.fault.

Research shows that people generally Research shows that people generally discount situational pressures that might discount situational pressures that might cause the average person to make the same cause the average person to make the same mistake.mistake.

Even though this is a difficult-to-overcome Even though this is a difficult-to-overcome human propensity, it’s an important thing to human propensity, it’s an important thing to avoid in design. If you create an error-likely avoid in design. If you create an error-likely situation, fix it, don’t blame the victim.situation, fix it, don’t blame the victim.

Will’s Ultimate RuleWill’s Ultimate Rule

1.1. There’s a big difference between There’s a big difference between being a grumpy old man and being a grumpy old man and making a legitimate point. The making a legitimate point. The goal of human factors is to improve goal of human factors is to improve human/machine interaction. Most human/machine interaction. Most of the time, if you make a mistake of the time, if you make a mistake using a product, it’s a design flaw, using a product, it’s a design flaw, not a human flaw.not a human flaw.

Human FactorsHuman Factors

Systems approach:Systems approach: Operator + machine/device + environment.Operator + machine/device + environment. Any failure = system failure. That’s to be avoided.Any failure = system failure. That’s to be avoided. There’s a lot more flexibility in manipulating the There’s a lot more flexibility in manipulating the

machine/device than in manipulating the operator.machine/device than in manipulating the operator. Consequences of failure:Consequences of failure:

Bad press (Microsoft).Bad press (Microsoft). Lost productivity.Lost productivity. Lost profit.Lost profit. Serious injury/death.Serious injury/death.

Human FactorsHuman Factors

Definition:Definition: ““The study of those variables that The study of those variables that

influence the efficiency with which the influence the efficiency with which the human performer can interact with the human performer can interact with the inanimate components of a system to inanimate components of a system to accomplish the system goals.” (Proctor accomplish the system goals.” (Proctor & van Zandt, 1994, p.2)& van Zandt, 1994, p.2)

Human FactorsHuman Factors

Or:Or: ““Human factors is that branch of science and Human factors is that branch of science and

technology that includes what is known and technology that includes what is known and theorized about human behavioral and theorized about human behavioral and biological characteristics that can be validly biological characteristics that can be validly applied to the specification, design, applied to the specification, design, evaluation, operation, and maintenance of evaluation, operation, and maintenance of products and systems to enhance safe, products and systems to enhance safe, effective, and satisfying use by individuals, effective, and satisfying use by individuals, groups, and organizations.” (Christensen, groups, and organizations.” (Christensen, Topmiller, & Gill, 1988, p.7, as cited in Proctor Topmiller, & Gill, 1988, p.7, as cited in Proctor & van Zandt, 1994, p.2)& van Zandt, 1994, p.2)

Human FactorsHuman Factors

Basic human capabilities:Basic human capabilities: PerceptualPerceptual Attention spanAttention span Memory spanMemory span Physical limitationsPhysical limitations Etc.Etc.

Historical Antecedents: Historical Antecedents: PsychophysicsPsychophysics

Weber (1846):Weber (1846): How can we tell that two stimuli differ?How can we tell that two stimuli differ? Weber’s Law: Weber’s Law: I/I = k. I/I = k. Application: Recognizing that an indicator Application: Recognizing that an indicator

light has come on.light has come on. Fechner (1860):Fechner (1860):

Attempt to produce a scale to relate a physical Attempt to produce a scale to relate a physical stimulus to the sensation produced.stimulus to the sensation produced.

Fechner’s Law: S = k log(I).Fechner’s Law: S = k log(I). Demonstrate the use of empirical methods Demonstrate the use of empirical methods

to understand human performance.to understand human performance.

Historical Antecedents: Historical Antecedents: PhysiologyPhysiology

Helmholtz:Helmholtz: Nervous transmission is not instantaneous.Nervous transmission is not instantaneous. Attach electrodes at two points on a frog leg, Attach electrodes at two points on a frog leg,

stimulate, look for effect. Difference in time can stimulate, look for effect. Difference in time can be used to compute speed of nervous be used to compute speed of nervous transmission.transmission.

Speed = 27 m/s.Speed = 27 m/s. If nervous transmission is not If nervous transmission is not

instantaneous, then we can study instantaneous, then we can study components, including mental components.components, including mental components.

Historical Antecedents: Historical Antecedents: TimingTiming

Donders (1868):Donders (1868): Analyze components of speeded tasks:Analyze components of speeded tasks:

Detect.Detect. Identify.Identify. Discriminate target from other stimuli.Discriminate target from other stimuli. Select a response.Select a response.

Subtractive method: Create tasks that vary by Subtractive method: Create tasks that vary by only one component, compare times in the only one component, compare times in the various tasks to compute how long each various tasks to compute how long each component takes.component takes.

We can actually break mental activity into We can actually break mental activity into its component parts. Response time is the its component parts. Response time is the handle on doing this.handle on doing this.

Historical Antecedents: Historical Antecedents: Role of Mental ActivityRole of Mental Activity

Wundt (1879):Wundt (1879): First psychology laboratory.First psychology laboratory. Believed that mental events play a Believed that mental events play a

causal role in human behavior.causal role in human behavior. Understand mental by decomposing Understand mental by decomposing

sensory and perceptual experience into sensory and perceptual experience into basic elements.basic elements.

Introspection.Introspection. The method had problems, the ideas The method had problems, the ideas

are still with us.are still with us.

Historical Antecedents: Historical Antecedents: MemoryMemory

Ebbinghaus (1885):Ebbinghaus (1885): Created lists of nonsense syllables, Created lists of nonsense syllables,

memorized them, studied properties of memorized them, studied properties of memory (e.g., savings).memory (e.g., savings).

Demonstrated empirically that Demonstrated empirically that mental constructs like memory could mental constructs like memory could be studied in the laboratory.be studied in the laboratory.

Historical Antecedents: Historical Antecedents: AttentionAttention

James (1890):James (1890): Outlined the basic components of Outlined the basic components of

attention.attention.

Historical Antecedents: Historical Antecedents: Information ProcessingInformation Processing

We have the basic foundation for a We have the basic foundation for a human information processing approach:human information processing approach: Cognition is a series of operations Cognition is a series of operations

performed on information originating from performed on information originating from the senses.the senses.

Human factors implication: The human Human factors implication: The human operator can be analyzed in the same way as operator can be analyzed in the same way as the machine/device.the machine/device.

For example, a computer has input, For example, a computer has input, processing, output just like the operator.processing, output just like the operator.

Human FactorsHuman Factors World War II was a major force in bringing all World War II was a major force in bringing all

of this together. New technologies, many of this together. New technologies, many untrained users, and profound consequences untrained users, and profound consequences of failure highlighted the critical need for of failure highlighted the critical need for human factors research.human factors research.

Find human factors research applied to:Find human factors research applied to: Military technology.Military technology. Nuclear power plants.Nuclear power plants. Aviation.Aviation. Automobiles.Automobiles. Consumer products.Consumer products. Human-computer interaction.Human-computer interaction.

Human Factors Human Factors PsychologyPsychology

Lecture 1: Course IntroductionLecture 1: Course IntroductionEndEnd

References:References: The notes are based on Proctor, R. W., & van The notes are based on Proctor, R. W., & van

Zandt, T. (1994). Zandt, T. (1994). Human factors in simple Human factors in simple and complex systems.and complex systems. Boston: Allyn and Boston: Allyn and Bacon.Bacon.

Most pictures and bad design examples are Most pictures and bad design examples are from Darnell, M. J. (2003). from Darnell, M. J. (2003). Bad human Bad human factors designs.factors designs. Retrieved May 10, 2003 from Retrieved May 10, 2003 from http://www.baddesigns.com.http://www.baddesigns.com.