More generally, it is worth noting the basic point that in the many experiments which seek to study time perception, the observer's percept is never directly observable.
(Example: the individual observes a vehicle. The time needed is not directly observable and therefore it is rejected).
Because the paramecia are not directly observable without instruments, we can only hypothesize that there are objects being observed for which the invariant geometric relations hold.
Paul seems to agree when he writes that "the unconscious mind... is by definition not directly observable".
Propositions in this language would describe objectively existing, directly observable states of affairs or events.
Such features as colour, ripple marks, mud cracks, raindrop imprints, and slump structures are directly observable in the field.
Consequently, it was the most distant object ever recorded that was bright enough to be directly observable with the unaided eye.
They are not directly observable.
Unlike cognitive states, social action is directly observable.
Determinants are not directly observable but can be measured indirectly.
Feelings are not directly observable, but have measurable correlates or consequences.
