I've been coding this new app with W for the past few days and this idea intrigued me. I've been taking inspirations from other apps to design the look and feel of the app, and I wonder if it's just based on my expectations because I'm a user of those apps, and whether they're transferrable if you're not a user.

It feels familiar to me, but it might not to others. However, since those apps are popular, I think it's safe to say it's good design to copy from.

When a user comes to your website and tries to do/use something, they come with preconceived notions and expectations, based on past experiences.

There's a term for this, it's called Jakob’s Law, and it's coined by Jakob Nielsen, a User Advocate and principal of the Nielsen Norman Group which he co-founded with Dr. Donald A. Norman (former VP of research at Apple Computer)

The law states:

Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know.

A few takeaways:

• Users will transfer expectations they have built around one familiar product to another that appears similar.
• By leveraging existing mental models, we can create superior user experiences in which the users can focus on their tasks rather than on learning new models.
• When making changes, minimize discord by empowering users to continue using a familiar version for a limited time.

Some examples:

• Form controls: form toggles, radio inputs, and buttons originated from their tactile, analog counterparts
• YouTube redesign: easing users into a new design, giving them the choice to preview (and revert), to gain familiarity and to submit feedback; empowering users to switch when they're ready.

More

• End of Web Design
• Top 10 Mistakes in Web Design
• The Power Law of Learning: Consistency vs. Innovation in User Interfaces
• Jakob's Law of Internet User Experience (2 min. video) (Video)

Check out Laws of UX for more.