Distractibility

Winning the Nobel Prize inevitably brings with it, besides a brief period of wider publicity (which in America evaporates particularly fast), a steady stream of invitations, varied honors and recognitions, as well as more general public involvement. Professors and scientists in American life are usually not exactly at the top of the social ladder, nor are they used to much recognition. Personally, I rather like this, because it helps not to attach overgrown significance to one s importance, keeps one humanized, and, most important, allows one to stay centered without much distraction from one s work. It was, therefore,... 

The accident at the Three Mile Island nuclear plant clearly demonstrated that an alarm system can be counterprociuc tive. An excessive number of alarms can distract the operator s attention from the real problem that needs to be addressed. Alarms that merely tell the operator something that is already known do the same. In fac t, a very good definition of a nuisance alarm is one that informs the operator of a situation of which the operator is already aware. The only problem with applying this definition is determining what the operator already knows. 

Another serious distraction to a process operator is the multiple alarm event, where a single event within the process results in iTuuti-ple alarms. When the operator must individually acknowledge each alarm, considerable time can be lost in silencing the obnoxious annunciator before the real problem is addressed. Air-handling systems are especially vulnerable to this, where any fluctuation in pressure (for example, resulting from a blower trip) can cause a number of pressure alarms to occur. Point alarms (high alarms, low alarms, status alarms, etc.) are especially vulnerable to the multiple alarm event. This can be addressed in one of two ways ... 

For single rings (i.e. mononuclear systems) up to ten atoms in size, there is no question but that Hantzsch-Widman names are overwhelmingly the most widely used, and specialists can be presumed to recognize them readily. However, when one of the trivial names of Table 1 can be used, it prevails almost exclusively. Thiophene will be immediately understood by specialists and most nonspecialists, whereas thiole will distract the reader s attention from the chemistry while he considers the writer s intention is the Hantzsch-Widman system indeed being used, or is it a typographical error Chemical Abstracts also uses these trivial names in its indexes. 

Noise An unwanted sound that causes annoyance or distraction. 

Off-site groups. Off-site training provides a concentrated focus and eliminates distractions. In addition, off-site meetings can often help promote a sense of teamwork among participants. 

When planning an on-site review, worit to be sure that your visit will not be too disruptive. You do not want your visit to distract people from system installation and become the cause of a delay, so tiy to keep your visit brief. You should not need more than a day at a time on site, and should only do on-site reviews infrequently. 

The worker closed valve B very frequently as part of his everyday job. The operation of A was embedded within a long sequence of other operations that were similar to those normally associated with valve B. The worker knew that he had to close A in this case, but he was distracted by a colleague and reverted back to the strong habit of operating B. Possible cause intrusion of a strong habit due to external distraction (correct intention but wrong execution). 

At the time that the alarm occurred, the worker was helping a colleague to fix a problem on an adjacent panel. The initiating event was therefore a distraction from another person (see Figure 2.15). 

The fact that the worker normally operated reactor B, and he reverted to this operating mode when distracted, indicates that the internal error mechanism was a Stereotype Takeover. 

The PIFs increased the likelihood of the strong stereotype takeover in the case study were the fact that the worker was more used to operating the valve for reactor B than reactor A, together with the distracting environment. In addition, the panel was badly designed ergonomically, and valves A and B were poorly labeled and quite close physically. On the basis of the evaluation of the PIFs in the situation, the internal error mechanisms could be stereotype takeover or spatial misorientation. 

Further links exist between the PIF concept and topics considered in previous chapters. In Chapter 2 the sequential model developed by Rasmussen to represent the error process from its initiator to its consequences was described (Figure 2.9). In this process, the PIFs were shown as being involved in both the initiating event and the internal error mechanisms. In the application example of the model in Appendix 2C, the PIF which constituted the initiating event was the distracting environment, and poor ergonomics of the panel was a PIF which influenced the internal error mechanism. 

Defensive avoidance Can take a number of forms. For instance, a person could become selectively Inattentive to threatening cues and avoid thinking about the dangers through distracting activities. Another form of defensive avoidance is "passing the buck" where someone else is relied upon to make the decision. 

TASK STEPS (CUES) (ACTIONS) FEEDBACK CHARACTERISTICS DEPENDENCIES DISTRACTIONS COMMENTS... 

Initial Alert Aleiting/Signal Detection of initial stages of problem Distraction/Absent-Mindedness/Low Alertness... 

Is there a mechanism for keeping place in a sequence of instructions, so that it can be returned to after an interruption or distraction ... 

Level of distractions score (score 7, ideal value 1)... 

Figure 5.9 illustrates some of the possible error reduction strategies available. Apart from the specific strategies set out in Figure 5.9, the PIF analysis also indicates which PIFs should be modified to reduce the likelihood of error. In the case of the chlorine loading example, the major scope for improvements are the reduction of time stress and distractions and the development of better quality procedures. 

The basic premise of the SLIM technique is that the probability of error associated with a task, subtask, task step, or individual error is a function of the PIFs in the situation. As indicated in Chapter 3, an extremely large number of PIFs could potentially impact on the likelihood of error. Normally the PIFs that are considered in SLIM analyses are the direct influences on error such as levels of training, quality of procedures, distraction level, degree of feedback from the task, level of motivation, etc. However, in principle, there is no reason why higher level influences such as management policies should not also be incorporated in SLIM analyses. 

Ideally, data bases will have been developed within a company such that predetermined PIFs are associated with particular categories of task. If this is not the case, the analyst decides on a suitable set of PIFs. In this example, it is assumed that the main PIFs which determine the likelihood of error are time stress, level of experience, level of distractions, and quality of procedures. (See Section 5.3.2.6.)... 

These ratings can be interpreted as follows. In the case of the Time Stress PIF, all the operations have a high level of time stress, apart from close test valve, where stress is low. The operators are very experienced in carrying out all the tasks. Distractions are moderately high for close test valve, but otherwise low. Procedures are poor for secure locking nuts and secure blocking device, but above average for the other two tasks. 

OPERATION TIME STRESS EXPERIENCE DISTRACTIONS PROCEDURES... 

Distractions or competing activities (demand/resource mismatch). Experience or familiarity with the task (useful for identifying slips and mistakes)... 

Wrong instructions received (R2) Wrong instructions transmitted (T2) High noise levels. Distractions. Unfamiliarity with instructions. Retrieval from memory rather than job card used. 

Log book/record card not filled in, 1.3 or incorrectly filled in (T1, T2) Lack of time. Lack of perceived importance. Distractions. 

TIME OP SYSTEM STATUS INFO AVAILABLE OPERATOR EXPECTA- TION PROEOURE (WRITTEN, MEMORIZED) DECISION/ COMMUNICATION ACT EQUIP- MENT/ LOCATION FEEDBACK SECONDARY DUTIES AND DISTRACTIONS COMMENTS 1... 

Make PA announcement for personnel to stop hotwork and stay away from MSM PA systems This message takes up time and distracts operator from watching Fire Gas panel. Consider taped messages. 

Forget to blowdown (due to workload, distractions, or low prominence of information). 

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