PS. I should add that before you get carried away with the recent 'advice' by Nieuwenhuis et al. (2011, Nature Neuroscience) consult VIckers and Altman (2001)! ******************************************************************** Philip Quinlan E-Mail: ptq1(a)york.ac.uk Department of Psychology FAX: (01904) 323181 The University of York Tel: (01904) 320000 Ext. 3135 Heslington Direct : (01904) 323135 York YO10 5DD U.K. ********************************************************************