Designing Experimental Webapps and Avoiding Bias

I am designing a webapp for psychological research and my goal is two fold:

  1. Make a user feel as though they can trust this experiment (especially when they look at the consent form). University IRB offices often ask for many disclosures that may look scary.
  2. Avoid any bias in the design of the website.

In our experiment, we are testing how individuals react to someone who is a member of an affinity group (such as an alum of the same university).

This will be presented as rapid images and then they will be asked to quickly respond positively or negatively.

What are some considerations, I should take into account while designing the web-app?

So far I've considered:

  1. Color Theory. Colors such as blue have been shown to induce trust while white doesn't have a biasing effect in the same way studies have shown red does.
  2. Randomization of ordering. In terms of how the data is presented.

What else haven't we thought of in terms of avoiding bias/increasing user trust (while not biasing a user)