A minimal model m4_m0 was fitted according to the structure of m2. All EMOTIKON tests were included in m4_mall. Six additional models were fitted (m4_mRUN, m4_mStar, m4_mS20, m4_mSLJ, m4_mBPT, & m4_mOLB), with each dropping one EMOTIKON test.
LRT shows no improvement of model fit for including interactions between Simon task parameters (i.e., Congruence, Colour, and Side) and EMOTIKON tests (Run, Star, and OLB).
Next, Run, Star and, OLB are included in the random effects without CP (i.e., m7) and with (i.e., m8).