UNIT 3 or UNIT 4

[nicestllmao]

Which one is easier? More intresting? Less content?

[Soul_Khan]

Less content - I would say Unit 4. See you choose to do an extended investigation which means that you exclude a couple of chapters.
Difficulty: Theories of learning, mechanisms of learning, etc. are not that bad however mental health is pretty difficult.

I enjoyed some parts of Unit 4 such as memory, sleep, and consciousness, forgetting, etc. a lot more than the stuff that we're learning in Unit 4, so I'd definitely go with Unit 3 as more interesting. But classical conditioning/operant conditioning is also really interesting at the moment.

I'd get back to the question once I start studying for the extended investigation

[Felicity Wishes]

Less content - unit 4 but personally, I found unit 3 more interesting and easier.

[WINGARDIUM]

Both are interesting, U4 easier (and less content). Learning = more application based questions. Mental Health is very straightforward.