This paper presents a predictive model of a simple, but
important, data entry task. The task requires participants to
perceive and encode information on the screen, locate the
corresponding keys for the information on different layouts of
the keyboard, and enter the information. Since data entry is a
central component in most human-machine interaction, a
predictive model of performance will provide useful
information that informs interface design and effectiveness of
training. We created a cognitive model of the data entry task
based on the ACT-R 5.0 architecture. The same model
provided good fits to three existing data sets, which
demonstrated the effects of fatigue with prolonged work,
repetition priming, depth of processing, and the suppression
of subvocal rehearsal. The model also makes predictions on
how performance deteriorates with different delays after
training, how different amounts of rehearsal during training
affect retention, and how re-training helps retention of skills.