To be successful in store, we must have fluency in consideration. Take the example of letters which we put on our POS or packaging design. We sometimes see information written in capital letters mostly for aesthetic reasons. Unfortunately, this creates a barrier for the autopilot to process the information.
Words presented in capital letters forces our brain to behave as if we had just learned to read. We must read letter by letter. Consequently, this makes reading relatively slow and energy consuming. Capital letters might look nice. But they are less fluent and therefore less effective if the message we send out in the store relies on efficient perception. So never use capital letters on your POS.