To add my penny’s worth to this. Years ago, my final thesis at university was about the perception and acceptance of designed information systems.
Specifically I wanted to study the effectiveness of travel signage systems which needed to work, even if the recipient did not speak the given language. I spent a month travelling around a Europe by train, documenting the good, the bad and the ugly; how placement, font, colour, etc, etc, affected the experience with both a designer and end-user head on.
I did loads of research on signage systems (see Margaret Calvert and Jock Kinneir – very UK centric, but relevant all the same). Most importantly this all lead me to delve fairly deeply into the psychology of how the human brain perceives and accepts lexical and pictorial information. How context, visual noise etc has a huge bearing.
Importantly, How – despite the fact we think we do – we never look at things objectively and moreover see only the information expect to see – more specifically, we only perceive the information we need to receive. This can prove potentially catastrophic in certain situations if the the expected information leaves out pertinent elements.
Think about last time you went into the kitchen to find your favourite mug. You didn’t see what colour the tea-towel was, or whether you needed to refill the washing up liquid, etc. You just found your cup and made a coffee. This is hugely important to human survival, in terms of the fight or flight mechanism. To be distracted by what types of birds are singing is hugely detrimental when being chased by a sabre-toothed tiger!
This was only one aspect. There are so many other factors thar govern how we perceive and act on any given information. It is a rabbit hole you could spend a a lifetime studying down, but it is hugely fascinating and as a grounding has served me very well throughout my career. I think psychology should be a requisite of any design education, but for signage and information system design, it is a definite necessity.