Insight learning can also be latent.
How though? Doesn't the organism learn the solution to the problem in the period of incubation and verifies it immediately?
Okay, I'll try to explain my logic through an example. Correct me if I'm wrong.
Let's say that someone is trying to solve a certain puzzle. Eg, let’s say the person is given this stimulus: "IX". And they are asked to make it '6' or 'six' using only one line.
In the preparation stage they identify the elements of the stimulus, and the instructions that they are given. Eventually they become frustrated etc, and reach the incubation stage, when they may not be solving the problem consciously (thought process is still occurring on a subconscious level). They experience the 'ah-ha' moment as they realise the answer to the problem. Now, they do not necessarily have to display that they have 'realised' the answer to the problem – almost ‘self-verification’ if you will.
They have the choice to display that they have undergone the learning process (it’s a form of cognitive learning, so they could just look at the answer and an observer would not be able to determine whether the individual actually ‘learned’ the answer. This also depends on the experimental conditions) – like in latent learning. Therefore afaik, insight learning can be latent as well. I’ll let you know if I can think of a better example.