Dept. of Computer Science, George Washington University, 801 22nd Street NW, Washington, DC 20052, USA
C-C. Tsai
Graduate School of Technological and Vocational Education, National Taiwan University of Science and Technology, #43, Sec. 4, Keelung Rd., 106 Taipei, Taiwan
J. Underwood
Dept. of Social Sciences, Div. of Psychology, Nottingham Trent University, Burton Street, Nottingham, NG1 4BU, UK