I'm new to mixed models, and I'm having trouble trying to figure out what the random structure should be for a specific example.
I'm using a shooter bias task (the paradigm where subjects are faster to shoot an armed black target) and I am interested in a 3-way interaction between Target Race (Black/White), Target Object(Gun/NoGun), Inhibitory Ability (continuous variable where higher numbers are better inhibitory ability).
DV = Reaction time
Fixed Factor 1 = Target Race (dichotomous variable; repeated measure) Fixed Factor 2 = Target Object (dichotomous variable; repeated measure) Fixed Factor 3= Inhibitory Ability (continuous variable)
Random Factor = SubjectID
I am interested in the 3-way interaction, and while I understand the fixed factor model, specifying the random factor model has never made sense to me.
Assuming, I'll be using LME for R...
Reaction Time ~ Target Race + Target Object + Inhibitory ability+ all two-way interaction terms + three-way interaction term + ...random model....?
would the random model be something like (Target Race:Target Object:Inhibitory Ability | SubjectID)? I really don't get how to specify the random model. So, any help would be appreciated. Including readings on how to specify the random effects structure would be appreciated.