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As a developing discipline, research results in the field of human computer interaction (HCI) tends to be "soft". Many workers in the field have argued that the advancement of HCI lies in "hardening" the field with quantitative and robust models. In reality, few theoretical, quantitative tools are available in user interface research and development. A rare exception to this is Fitts' law. Extending information theory to human perceptual-motor system, Paul Fitts (1954) found a logarithmic relationship that models speed accuracy tradeoffs in aimed movements. A great number of studies have verified and / or applied Fitts' law to HCI problems, such as pointing performance on a screen, making Fitts' law one of the most intensively studied topic in the HCI literature.
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Accot et al. (1997) studied this question.