1ISE 412

Human Error

2ISE 412

General People make errors routinely

recall attention lesson decision making lessons display, control lessons

Fundamental categories (“first cut”) slips - result from automatic behavior mistakes - result from conscious deliberation

3ISE 412

Slips

Most everyday errors are slips.

go home instead of to a meeting after class putting the cereal in the refrigerator and the milk in the

cupboard calling a well-known friend by another name etc.

Intend to do one thing and end up doing another.

Associated with skilled behavior.

4ISE 412

Types of slips Capture errors: a frequently done activity takes charge

instead of (captures) the one intended. Occurs when 2 action sequences have initial stages in common, but one is

more familiar than the other.

Description errors: the intended action has much in common with other possible actions Internal description of intent is not sufficiently precise. Perform the correct

action on the wrong object.

Different actions having similar descriptions leads to problems, especially with skilled operators not paying full attention.

You go to your room to change clothes for dinner, but find yourself ready for bed instead.

A person intends to put a lid on the sugar bowl, but instead puts it on a coffee cup (w/ same size opening.)

5ISE 412

Types of slips (cont.) Data driven errors: automatic actions are triggered by

sensory data and can intrude on other actions.

Associative activation errors: internal thoughts and associations trigger response.

“Freudian slips”

I intend to tell someone my phone number, but I’m looking at my VISA bill and start to give my account number.

My older brother answered the phone at the end of dinner and politely said, “May I be excused please?”I have been thinking about an old friend when I pass a student I know well - I call the student by the name of my friend.

6ISE 412

Loss-of-activation errors: forgetting Activation of goals has decayed.

Mode errors: Actions have meanings that depend on the mode of operation of the device. errors occur when the mode is not the one that is intended.

Types of slips (cont.)

You go to the kitchen and open the refrigerator door, only to stand and stare at the contents, trying to remember what you came in to get.

StopwatchComputer applications

Automatic pilotsMicrowave ovens

7ISE 412

Design lessons from slips PREVENTPREVENT

Minimize problems by increasing “distance” between possible actions.

Confirmation.

Problem: the user is confirming the action, not the file name. Confirmation alone cannot detect and prevent all slips.

DETECT AND CORRECTDETECT AND CORRECT Eliminate irreversible actions (e.g., automatic backups, “undo”

functions.)

CAR FLUIDS: oil, transmission, brakes, windshield, radiator, battery. Designers minimize errors through different shapes, sizes, and colors of fluids, indicators, and containers.

COMPUTER: Are you sure you want to delete the file “my most important work”?

8ISE 412

Examples Commentary: Human Error and the Design of Computer Systems

(http://www.jnd.org/dn.mss/error_design.html)

Study: Human Error Causes Most Security Breaches (http://www.cioupdate.com/trends/article.php/2120371)

Human Error and Clinical Systems (HECS'99) (http://www.dcs.gla.ac.uk/~johnson/papers/HECS_99/)

etc …

9ISE 412

Mistakes A “planning failure”

actions go as planned, but the plan was bad

Errors of judgment, inference, etc.

Result in incorrect intention incorrect choice of criterion incorrect value judgment.

Examples from your decision making lab …

10ISE 412

Error Classification: Rouse

Stage Error

1. Observation of system state

Improper rechecking of correct readings

Erroneous interpretation of correct readings

Incorrect readings of appropriate state variables

Failure to observe sufficient number of variables

Observation of inappropriate state variables

Failure to observe any state variables

2. Choice of hypothesis

Hypothesis could not cause the values of the state variables observed

Much more likely causes should be considered first

Very costly place to start Hypothesis does not functionally

relate to the variables observed

3. Testing of hypothesis

Stopped before reaching a conclusion

Reached wrong conclusion

Considered and discarded correct conclusion

Hypothesis not tested

11ISE 412

Error Classification: RouseStage Error

4. Choice of goal

Insufficient specification of goal

Choice of counterproductive or nonproductive goal

Goal not chosen

5. Choice of procedure

Choice would not fully achieve goal

Choice would achieve incorrect goal

Choice unnecessary for achieving goal

Procedure not chosen

6. Execution of procedure

Required stop omitted Unnecessary repetition

of required step Unnecessary step

added Steps executed in

wrong order

Step executed too early or too late Control in wrong position or range Stopped before procedure

complete Unrelated inappropriate step

executed

12ISE 412

Err

or C

lass

ifica

tion:

Ras

mus

sen

Sta

rt

The

situ

atio

n is

aro

utin

e si

tuat

ion

for

whi

ch t

he o

pera

tor

has

high

ly s

kille

d ro

utin

es?

But

the

ope

rato

rex

ecut

es a

ski

lled

act

inap

prop

riate

ly

The

act

is n

ot p

erfo

rmed

with

adeq

uate

pre

cisi

on (

time,

forc

e, s

patia

l acc

urac

y)M

anua

l var

iabi

lity

The

situ

atio

n de

viat

esfr

om n

orm

al r

outin

e.D

oes

oper

ator

res

pond

to t

his

chan

ge?

Ope

rato

r re

aliz

es a

ndre

spon

ds t

o ch

ange

s.Is

the

situ

atio

nco

vere

d by

nor

mal

wor

k kn

ow-h

ow o

rpl

anne

d pr

oced

ures

?

The

act

is p

erfo

rmed

at

wro

ng p

lace

, co

mpo

nent

insp

ite o

f pr

oper

inte

ntio

n

Yes

No

Top

ogra

phic

mis

orie

ntat

ion

Doe

s ot

her

high

ly s

kille

d ac

tor

act

ivity

inte

rfer

e w

ith t

ask?

Ste

reot

ype

take

over

Yes

No

Ste

reot

ype

fixat

ion

Doe

s th

e op

erat

orre

aliz

e th

is?

Fam

iliar

pat

tern

not

reco

gniz

ed

Doe

s op

erat

orre

spon

d to

prop

er t

ask-

defin

ing

info

rmat

ion?

Doe

sop

erat

orre

call

proc

edur

eco

rrec

tly?

Oth

er s

lip o

fm

emor

y

Mis

take

s,al

tern

ativ

es

For

gets

isol

ated

act

Yes

, bu

tfa

ilsdu

ring

exec

utio

n

Yes

Yes

Yes

No

No

No

Yes

The

situ

atio

n is

uni

que,

unkn

own,

and

cal

ls f

orop

erat

ors

func

tiona

lan

alys

is a

nd p

lann

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Doe

s op

erat

or r

ealiz

e th

is?

Ope

rato

r re

spon

dsto

fam

iliar

cue

whi

ch is

inco

mpl

ete

part

of

avai

labl

ein

form

atio

n

No

No

Fam

iliar

asso

ciat

ion

shor

t cu

t

Doe

s th

e op

erat

orco

rrec

tly c

olle

ctth

e in

form

atio

nav

aila

ble

for

his

orhe

r an

alys

is?

Info

rmat

ion

not

seen

or

soug

ht

Info

rmat

ion

assu

med

not

obs

erve

d

Info

rmat

ion

mis

inte

rpre

ted

Are

fun

ctio

nal

anal

ysis

and

dedu

ctio

n pr

oper

lype

rfor

med

?

Sid

e ef

fect

s or

con

ditio

ns n

otad

equa

tely

con

side

red

Oth

er,

spec

ify

Yes

Yes

Yes

No No

Knowledge-basedRule-basedSkill-based

13ISE 412

Examples to classify A person intends to put a lid on the sugar bowl, but instead puts it on a

coffee cup (w/ same size opening.)

Rouse classification: _________

Rasmussen classification: _________

The stock clerk entered 11,000,000 into the shares field instead of the dollars field, resulting in the sale of $50,000,000 of stock and a brief but memorable run on the stock market.

• Rouse classification: _________

• Rasmussen classification: _________

14ISE 412

Examples to classify

In the absence of explicit information, the power system operator assumed the feeder line from the north was still providing power to the grid.

Rouse classification: _________

Rasmussen classification: _________

During an airshow demonstration, the Airbus A320 crashed during low-level maneuvers because the pilot had left the autopilot in a mode that did not allow manual correction of airspeed.

Rouse classification: _________

Rasmussen classification: _________

15ISE 412

Design lessons from mistakes PREVENT

Situation awareness.

Training.

Aiding.

DETECT AND CORRECT Provide feedback on the real or expected results of decisions.

GPS systems use maps to display navigation information so users can understand where they are in the world and make decisions accordingly.

RECALL Klein’s work on naturalistic decision making.

EXPERT SYSTEMS based decision aids give decision makers the benefits of years of experience gained by others in the field.

PREDICTOR DISPLAYS in aircraft show the predicted result of planned control actions.

16ISE 412

Systems View to Prevent Errors From your book

Environmental factors spills, obstructions, etc. glare, noise, temperature, etc.

Job factors workload, shift rotation, fatigue, etc. ergonomics, procedures, etc.

Social/cultural factors managerial practices, incentives, etc. social norms, morale, etc. training, reminders, visibility

Hazard analysis Recall ISE 311, Fault Tree Analysis