Errors: An Inherent Part of Human-System Performance - Foundations for Designing User-Centered Systems - page 290

Table 10.2 The CREAM
genotypes of human error

Person-related Observation

Interpretation
Planning
Temporary
Permanent

Organization-related Communication

Training
Ambient conditions
Working conditions

Technology-related Equipment failure

Procedures
Temporary interface problems
Permanent interface problems

refers to these as the logical phenotypes of human error—each of which can
manifest itself in several ways (shown in italics):

• Timing: the action is too early/too late/omitted.
• Duration: the action is too long/too short.
• Force: the action uses too much/too little force.
• Distance: the action is carried on too far/too short.
• Speed: the action is too fast/too slow.
• Direction: the action is performed in the wrong direction or involves the wrong
type of movement.
• Object: the action was carried out on a proximal object/similar object/unrelated
object rather than the required object.
• Sequence: in a sequence of actions there was an omission/skip forward/skip
backward/repetition/reversal or the wrong action was performed.

In addition, the CREAM makes provision for the inclusion of correct actions.
Hollnagel ( 1998 ) suggests that a category labeled no erroneous action should be
incorporated, either by adding it to each of the classification groups or by keeping
it as a separate group.
The category of error mode to which a particular instance of an erroneous
action belongs may not always be immediately obvious. In such cases, the par-
ticular situation at hand has to be carefully considered before any judgment can be
made. This need for considered judgments is critical to the field of human error
research, because the labeling of a particular action as being erroneous is invari-
ably a judgment made in hindsight (Woods et al. 1994 ).
The other part of the CREAM taxonomy is made up of the possible causes, or
genotypes. These are divided into three main categories as shown in Table 10.2 .
There is one category for each of the main factors that contribute to system
performance: people, technology, and context (described as organization-related in
the CREAM).