A function of the consciousness with which it observes both external and internal phenomena or objects; when a stimulus crosses a certain threshold, it awakens the interest of the consciousness and moves into the central field of the attention. That is, the attention functions through interest; it follows things that in some way impress the consciousness and create a register. A stimulus that awakens interest stays in the central attentional field which we call the field of the "present." This is related to perception. All objects that are not strictly part of the given central object become gradually diffused in the attentional field, that is, less attention is paid to them. However, other objects which are not actually present may accompany or be linked to the central object through associative relationships. We call this attentional phenomena the field of the "co‑present" and it is related to the memory. In the act of evocation, one moves one's attention from an object in the attentional presence to an object in the co‑presence; this is possible because there is a register of both the object present and the co‑present object. Through co‑presence one can structure and interpret new data never before seen. We say that when one attends to an object, what is evident is made present, while the non‑evident appears in a co‑present way. This occurs in the consciousness when it perceives something, so that one always structures more than one literally perceives, overlaying other things onto the object under observation. The co‑presence also includes the different levels of consciousness; thus, in vigil there is a co‑presence of vigil. This gives rise to the different states (See Consciousness, Levels of; see Directed Attention and Tense Attention).