What is the deal with Graphical User Interface/app psychology?

If there was hard science behind UI design they wouldn't totally redesign everything every couple of years.

I would start with the classic: Don't Make Me Think by Steve Krug

https://en.m.wikipedia.org/wiki/Don't_Make_Me_Think

The Design of Everyday Things

Mid-to-late 00's had best UI design. Nowadays everything is less-functional and to do simple tasks you need to click through 5 different menus, and move your fingers in all directions, because there's no standard to do anything.

Just to see my watch later playlist on YouTube on my phone I need to click 2 buttons, scroll down through playlist list and click on the conventionally placed watch later playlist on the bottom of the list. What the fuck?

I wonder what all these UI specialists even do. Just blindly do everything upper management tells them to do, even if that makes no sense?

I think that's what is learnt on Design courses at university. Also ergonomics.

But IDK. I saw "professional" web-designers who don't consider colorblind peoples in their colors.

But I didn't ask if they had professional education.

Speaking as a designer, it’s important to separate the style/trend of a UI from its function. I think what you’re looking for is actually UX design.

As a discipline, User Experience uses evidence-based research to understand how and why users behave they do. This leads to specific design patterns and principles that underlie all the good UI design seen from the giants like Apple, Google, Microsoft, etc. It gives you the language to evaluate designs. This is the foundation of your UI and the rest is just style — fonts, colors, imagery and icons which is subjective and less important. I lost ambition to be a trendy UI designer, so every design looks the same, but usability will shines through. Clean, simple and accessible is timeless.

Study the articles from nngroup.com. They pretty much established the field of UX Design, with content talking about user behavior in the 1990s. https://lawsofux.com is a more attractive and consumable option, also heavily influenced by NN Group. Finally, accessible design is good design for all, not just those with disabilities. Understand the guidelines set by the W3C for accessibility, like minimum font sizes or contrast ratios for colors.

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Alan Dix’s book (aptly named “Human Computer Interaction”) is quite good, even if somewhat old by now. HCI is an actual academic discipline with, yes, tons of theoretical and empirical results that govern what a good UI should be. Many of which are indeed grounded in psychology, others in physiology, etc (what we call Human Factors). There is a whole special interest group of the ACM just about it: SIGCHI.

Do not confuse this with fashion/trends/taste. These change, resulting in widely different possible flavors of UI over the years. But the underlying principles are the same.

Another thing to remember is that the fact that Apple, Google, or someone else implemented an UI in a certain way doesn’t mean they are following best practices and guidelines. Novelty sells, even if at the end of the day it does a worse job of things…

Edit: added link to SIGCHI

Just wait until you hear about UX

Begin with The Design of Everyday Things. Is it specifically for tech or software? No and barely touches on it, but it outlines what UX is for and provides easy to imagine examples of realistic conflicts and solutions that are eminently realistic.

The ultimate goal is always intuitive interaction. I can’t appreciate the beauty of a functional object after it’s frustrated me when I tried to use it

This is one of the best/most effective UI courses I've seen that takes someone from 0 to very good. It's quite expensive though.

https://www.learnui.design/

Start with a book called “Tog on Interface”.

The book “Design of Everyday Things” might also provide some good background.

And then there are the endless Human Interface guidelines put out by Apple and many other companies that usually try to explain the “why” behind their decisions.

It may not be exactly what you’re looking for, but if you’re interested in user interface, I can’t recommend this book enough:
GUI Boopers by Jeff Johnson

Google for “Material Design Spec” for a super highly opinionated, highly-arbitrary, but still kind of interesting intro to UI standards.

UI design is increadibly complex.

A UI isn't just an app, or a program running on a screen, everything man has built to interact with by others have a UI, from simple tools cutlery, to complex industrial control systems.

UI design has a very simple goal, "simplify usage", from the shape of the handle of a knife to a color coded matrix of indicator lights at an industrial monitoring system, it all comes down to "simplify".

Unfortunately there are just so many, many different needs of the person interacting with different systems that there are very few exact rules to follow.

You mention apps, so let's limit outselves to software...

The first question that the UI designer needs to know is "what should the UI allow the user to do".

It could be as simple as "register a smartphone when issuing the phone to a user".

This means the UI needs to accept input of six pecies of data:

1. Manufacturer of the phone
2. Model of the phone
3. IMEI number of the phone
4. Name of the user
5. Date
6. Name of the person issuing the phone

Ok not that bad, so you make this, but then you quickly realize that the user of the system needs a way to check if the phone was added to the system correctly.

If this is just added in Excel, then it is a solved problem, but if you are building a completely new system, then you need to add a way to get a list of all phones issued in the system to the UI, you also need to add a way to update posts in the list.

Then you realize you it would be very helpful to have a way to see the actual status of phones in the system, there will be times to log if a phone is sent for service or if it gets stolen or so, so you add a status field.

After a few months of accumulating data, the list looks good, if a bit messy, you can't get a good overview of it.

So you add color coding to the status field, white for in storage, green for in production, yellow for on service, red for lost/stolen, grey for retired.

You have now a functioning UI.

Its incredibly cultural actually so there is no universal solution. Asian cultures tend to be able to and prefer having a higher density and more information compared to western world. Americans require more simplification than everyone else for some reason I recon iq.