[Freesurfer] Optseq2 and Mixed ER

Dear Freesurfer Support,

I am using optseq2 to design my experiment and was wondering whether ER or Mixed Block-ER would work best.

Here's a brief description of my expt: I am looking at the effects of exposure to emotional stimuli on contrast sensitivity (gabor patches) during Easy and Challenging types of visual search.

2 runs of 3 Emotion Types x 3 Contrast levels during Easy search

2 runs of 3 Emotion Types x 3 Contrast levels during Challenging search

All runs are 8 minutes long with 20 trials per condition.

Is ER or Mixed Block-ER more appropriate, and if the latter, how would that be entered?

Thank you so much,

Michelle