[Eeglablist] About contrasts and simple effects in LIMO

[Marina Pi Ruano]

Hello everybody,

I write this email because I would like to calculate simple effects with LIMO. I’ve already tried with the “contrasts” option. However, the graphs I get don’t make a lot of sense to me, which makes me think I must be doing something wrong. 

I have a 2x2 design. Specifically, 2 different groups of people (between-factor) and 2 different conditions for all subjects (within-factor). As I’ve found the interaction is significant, I would like to check the simple effects. Specially: (a) the simple effect of condition in Group 1, (b) the simple effect of condition in Group 2, (c) the simple effect of Group in Condition1, and (d) the simple effect of Group in Condition2. How should I write this information to LIMO? I’ve already tried this. For the simple effect of:
a) Condition in Group 1:	1 0 -1 0
b) Condition in Group 2:	0 1 0 -1
c) Group in Condition1:         1 -1 0 0
d) Group in Condition2:	        0 0 1 -1

Nevertheless, when trying to calculate (b) and (d), the program fails to respond. In addition, the graphs obtained for (c) are the same as the ones obtained for the interaction and the main effect of group, which makes me a bit skeptical about these analyses. 

It would be very appreciated if anyone could give some hints or advices in this regard.

Yours faithfully,
Marina Pi-Ruano