First includes those which increases processing capacity requirements either because they require more processing per unit time (for example dense or fast speeches and enumerations) or because their signal is noisy or distorted (for example heavily accented speeches, speeches with unusual grammar or logic, noisy physical environment and inadequate acoustic equipment). The second category includes speech segments which raise difficulties for the Listening Effort because of their brevity and lack of redundance (for example numbers, short words and names). Also errors in the interpreting of seemingly easy speech segments by attributting them to saturation or processing-capacity deficit involving earlier, more difficult segments and leading to the transfer of prcessing capacity and to a chain reaction in which the failure occurrs at some distance from the actual triggerers.
The concept of ‘processing capacity’ is also linked to the type of mastery of working languages required from interpreters. Because of time constraints and limited processing capacity, the interpreter not only has to know the words and linguistic rules in his/her working languages, but their active use in comprehension or production must be fast and take up little processing capacity; in other words, the interpreter’s linguistic knowledge must be highly ‘available’. This requirement is critical in interpreters, as opposed to translators, who do not have to share attention and who can devote minutes, hours or more to the comprehension of text segments or to the retrievel of words or linguistic rules for use in their target text.
The concept of ‘processing capacity’ can shed some light on the much debated issue of the desirability of working from an A into a B language or vice-versa. The issue of the ‘DIRECTION OF TRANSLATION’ can be addressed in terms of time and processing capacity requirements in the Listening Effort and in the Production Effort. If it can be shown that the Listening Effort takes up much more processing capacity, the A into B argument becomes more convincing. If, on the other hand, it turns out that it is the Production Effort which takes up much more processing capacity, the B into A argument becomes more plausible. If no major difference is found to exist between the two, both arguments would have to be assessed by reference to other factors, such as the individual interpreter’s command of the language involved, his/her flexibility in adapting the structure of the output to accommodate the incoming input despite anticipation difficulties, and any lexical or grammatical peculiarities of the source or target languages which might influence ease or difficulty of comprehension (for example the level of redundancy).