Human error

Human error 

If human try to do decision , there have possible to make error . 

Error have 4 stages : slip / lapse / mistake / violation 

Basic error types (1/2/3) : 

1. mistake ( decision making ) include two things : 

• knowledge based mistake ( KB ) : knowledge based violation / rule based violation

put heavy demands on attentional resources / fault diagnosis and trouble shooting

• rule based mistake ( RB ) : procedure memory

make use of “ if - then " rules / mistakes occur when the rules do not match the actual situation 

    2.  lapses : skill based slip , failure in the storage stage (memory stage ) 

    3.  slips : skill based lapse , failure in the execution stage , respond execution

accidentally pressed shutdown button when intended to press the delete button 

Intention （planning failure - mistakes ) ---attention (execution failure - slips , lapses ) --- success 

     4.  violation : knowledge based violation / rule based violation / skill based violation 

As human a decision maker should consider many factors , but not everyone can full consideration , so we can`t error free , but we can try to reduce the occurance of human error by trying to understand how and why it occurs  , but we can prevent error by : resilient strategies / design for safety / device design 

1. Failure in knowledge level :insufficient knowledge / working memory overload / overconfidence / fail to consider all alternatives 
2. Failure mode in skill level : interruption by other event i.e , answer the phone in the middle of thinking / activation of incorrect but stronger schema due to the share attributes / overattention i.e , beware of finger movement during touch typing 

Active VS. Latent failures : 

Active failures :direct interaction between user and system . effect immediately 

Adverse consequence within they system for a long time i.e , faulty maintenance , bad management 

After knowledge points to explain , there comes a movie : error and events leading to the crash of midland flight 092 

The first is to display a design flaw - a control relationship leads to violations of SR compatibility judge pilots difficulties. The second design flaw is the air conditioning system is located around the engine, different from the previous plane, and finally in that the combustion engine of human error, it is relevant to the left engine failure indicator, is located on the right side of the cockpit midline.

Introduction 

        The human`s error is the people do something without common sense or make mistake .

        Human error definition :  an erroneous action can be defined as an action which fails to produce the expected result and / or which produces an unwanted consequence .

        We make errors far less frequently than making correct actions , but when they occurs , the consequences can be disastrous .

        We can`t totally eradicate errors , and still the decision maker and the problem solver .through trying to understand what human error is , the types of error , how it occurs and why it occurs to reduce the occurrence .

        Human error come from : 1. Nature of task its environmental circumstances  2. Nature of the individual 3. Mechanisms governing performance .

        Intention : an expression of the end-state ( goal ) to be attained , components with a desired goal , sub-goals , a formulation of a plan , action execution .

Intention ( planning failure ), attention( execution failure )  and error ( intended path )

Human error types :

1.                   Slips : errors result from some failure in the execution stage of an action sequence , regardless of whether or not the plan which guided them was adequate to achieve its objective .

2.                   Lapses : errors result from some failure in the storage of an action sequence , regardless of whether or not the plan which guided then was adequate to achieve its objective .

3.                  Mistakes : deficiencies or failures in the judgemental and /or inferential processes involved in the selection of an objective or in the specification of the means to achieve it , irrespective of whether or not the actions directed by this decision- scheme run according to plan .

Cognitive stages and error type :

Three levels of performance (SRK) model :

1.                   Basic level of complexity – skill-based performance

      Sensorimotor performance take place without conscious control as smooth , automated , and highly integrated patterns of behavior / based on patterns stored in long-term memory /

2.                 Medium level of complexity – rule-based performance

     Consists of a goal-oriented “sequence of subroutines in a familiar work situation “ (rules ) / subroutines based on stored rules forms from previous experiences / very often , the goal is not explicitly formulated , but is found implicitly in the situation releasing the stored rules .

3.                High level of complexity – knowledge-based performance

     Relies upon a feedback control and a “ mental model “ of the system in question / used only when the stock of stored problem-solving routines is exhausted / slow , sequential , laborious and resource-limited conscious processing / process : setting local goals , initiating actions to achieve them , observing the extent to which the actions are successful and then modifying them to minimize the discrepancy between the presented position and the desired state .

Knowledge-based mistakes :

•         Occur in decision making stage
•         Incorrect plans of action are arrived at because of a failure to understand the situation (incorrect knowledge )
•         Make use of declarative knowledge
•         Put heavy demands on attentional resources and the central executive

5                   Often involves in fault diagnosis , troubleshooting and reasoning in a novel situation

Rule-based mistakes :

1.       Occur in the decision making stage when the situation is familiar because they have encountered similar situations in the past

2.       Make use of existing (IF(situation ) ,THEN(situation / action)) rules in the procedural knowledge 

3.       Mistakes occur when the if part of the rule invoked do not match the actual situation .

Skill-based lapses :

1.       Occur as a result of memory failure at the execution stage

2.       What we often called “ forgetfulnessz”

3.       Omission of action from a familiar sequence of actions

4.       Often due to interruption of thought resulting in momentary attentional failure

5.       Occur frequently in maintenance and installation procedures

Skill-based slips

1.       Occur in the response execution stage

2.       The right intention and plan is formed , but incorrectly carried out

3.       Sometimes termed a “ commission error “

4.       Involve in a routine and fairly automatic task in a familiar setting

5.       Require minimum attentional resource and central executive

6.       Can be due to either inattention or overattention

Failure mode at each level of performance

       Failure mode at slip based level

Inattention :

• .       Capture errors : attention momentarily redirected to internal preoccupation or external distractor at a time that it is needed to set the action along the currently intended pathway / activation of incorrect but stronger due to shared attributes / the current action departs from the norm .
• .       Interruption by the occurrence of external events : answer the phone in the middle of thinking – forgot the train of thought .

Failure mode at SB level  :

Inattention continue …

        Time delay between the formulation of intention and the action / perceptual confusion : mistaking a similar object to be the target object / entangling of two active schemata

Overattention :

        When attention is paid to the task at hand at an inappropriate time resulting in the disruption to the smooth running of an automated task

Failure mode at RB level :

        Strong-but –wrong rule from first impression / explain away of countersigns ( information against the activation of a particular rule ) and mistaking non-signs ( irrelevant information to the decision ) as signs ( information that satisfy the activation of that rules ) / information overload / rule strength : strong ( often used and successful ) rules need less increase in activation level to be activated .

Failure mode at KB level :

        Insufficient knowledge or expertise ( incorrect mental models ) / working memory overload : out of sight out of mind / confirmation bias : fail to consider all the alternatives , biased reviewing / overconfidence : experts tends to be confident in the correctness of their knowledge

Switching between levels :

        SB-RB level : attentional checks result in a detection of a deviation from the planned-for condition / attempt to apply a rule to correct the situation / if the corrective rules re easily found and successfully applied , performance is returned to the SB level

        RB-KB level : when the problem solver realize that none of the RB  solutions available is adequate to solve the problem / repeated cycles between KB and RB levels as various possibilities are explored .

        KB-SB level : when an adequate solution found / a formulation of a new plan of action requiring the execution of a fresh set of SB routine

Error detection and correction rate :

        Performance at each level : SB and RB performance happen far more frequently than KB performance / but opportunity for errors in the KB level of performance is a lot higher .

        Correction rate : SB- twice as high as those for RB errors ( almost all detected are corrected ) / RB- three times as high as those for KB errors / KB- poor record of error correction

Latent vs active failures :

        Active failures : associated with the direct interaction between the user and the product or system / effects are felt almost immediately

        Latent failures : adverse consequences that lie formant within the system for a long time , only becoming evident in combination with other factors / activities removed in time and space from the direct control interface / incorrect installation , faulty maintenance , bad management decision

        Designer`s role in system failure : often designer`s contribution to accidents or incidents are as latent failures as a result of poor design