A New Test of Throughput Invariance in Fitts' Law: Role of the Intercept and of Jensen's Inequality

This is the nearly final version of an article presented at HCI 2012 People and Computers XXVI, an annual conference of the British Computer Society held on September 12-14, 2012 in Birmingham (UK). The article appears on pp 119-126 of the conference proceedings. The paper having obtained the conference's Best full-paper award, it will be republished as such in the December 2012 issue of INTERFACES, the award winning magazine of the British Computer Society http://www.bcs.org/content/ConWebDoc/3