It will be the average of what is NOT modelled by the instruction / condition regressors and thus 010000 is testing if condition 1 > baseline differs from 0 Sent from my mobile phone Dr Cyril Pernet Brain Research Imaging Centre www.sbirc.ed.ac.uk/cyril/ ----- Reply message ----- From: "Yann Quidé" <[log in to unmask]> To: <[log in to unmask]> Subject: [SPM] Question about implicit baseline Date: Wed, Jul 10, 2013 03:43 Dear all, We have a question concerning implicit baseline. In an experiment using a block design, we have 3 different conditions within 3 different sessions (3 different instructions, ie inst1cond1, inst1cond2, inst1cond3; inst2cond1, inst2cond2, inst2cond3; inst3cond1, inst3cond2, inst3cond3), all modelled with no rest or fixation cross, all in the same order across session. If at the 1st level analysis, I want for example to have a look at the effect of cond1 (say whatever the instruction) and create the vector [1 0 0], what exactly will be my implicit baseline here? Will it be an average of anything occuring during the other conditions (ie an average of what happens in the 0 0 of my [1 0 0] vector)? Is there anything wrong it that approach? Thanks in advance for your thoughts. Best, Yann