1. Sequence Production Lab, Department of Psychology, McGill University, 1205 Dr Penfield Avenue, Montreal, Quebec H3A 1B1 Canada.
2. School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Queensland, 4072 Australia.
3. Australasia CRC for Interaction Design, PO Box 2008, Kelvin Grove, Queensland, 4059 Australia.
4. Department of Psychology, Macquarie University, Sydney, New South Wales, 2109 Australia.