Technical Translation: Usability Strategies for Translating Technical Documentation

Capacity Models 
Capacity models work on the assumption that the human cognitive system 
has a limited, finite set of resources. When we are aware of more than one 
stimulus, the available resources are allocated in varying amounts to differ-
ent stimuli. For instance, a complex stimulus will require more of the avail-
able resources with the result that there are fewer resources available for 
processing other stimuli. Accordingly, attention can thus be defined as “the 
process of allocating processing resources or capacity to various inputs” 
(Ellis & Hunt 1993:62). This model is demonstrated in what Ellis & Hunt 
(1993:63) refer to as the 
secondary technique and cognitive effort
. This 
technique is used to show how much cognitive effort (or processing re-
sources) is needed for a secondary task while a person is already performing 
a primary task. Experiments conducted on this basis showed that the more 
complex the primary task, the more difficult it is to perform a second task. 
Interestingly, the greater the cognitive effort required for a task, the better 
the memory for that task and related information (
ibid.
). 
Gavin (1998:38-39) characterises the model as follows: Competing stimuli 
produce non-specific interference – the two tasks do not directly interfere 
with each other but they do compete for the same finite set of resources. 
The more resources that are needed for one task, the fewer resources are 
available for the other task. It follows, therefore, that we can theoretically 
perform two tasks provided the total processing demand does not exceed 
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Attention & Selection
the available capacity. When total processing demand exceeds the available 
capacity, performance on one task deteriorates (cf. Raskin 2000:21). The 
allocation of resources is flexible and can be adjusted to meet the demands 
of stimuli.