learners may not know they are learning

In second language acquisition, there are many theories; one is the attention-processing theory. It can occur below the level of awareness, so (the) learners may not know they are learning.

Is THE optional? It seems here LEARNERS without THE would imply learners in general, rather than those who are using the attention processing theory; but in English we could say LEARNERS WHO ARE...ARE.... Then even without the we can still use a restrictive relative clause to define those LEARNERS.