Control of eye movements by working memory load.

During steady keying at a text processor touch typists scan copy and display in a repetitive way. Within a single cycle a certain text string is read from the copy by the subject and subsequently the remaining time is used to check the typed keys on the display. This behavioral pattern allows to analyse the input-output relationship between read characters and typed keys with respect to the storage characteristics of the working memory. In order to achieve a continuous transcription process the reading time is negatively correlated with the checking time. This allows to investigate the amount of information stored during the reading time and the chunking strategies. On the basis of model simulations evidence is provided that working memory load is not determined by a fixed capacity limit but by an increasing probability that the reading process is interrupted at the next word delimiter.