The fascination with the Other is inherently linked with the notion of the self. We are only created as subjects in relation to the other. Jacques Lacan's theory of the mirror stage is one way to understand the fascination/necessity/desire we have for images of the Other.

According to Lacan, humans are born undifferentiated from the world. We are not a subject because we know no Other to be in relation to. At first, when the child sees an image in the mirror, it still replaces this image of the Other with some sense of the self. Gradually, though, the mirror image becomes an image outside of the self: we become both subject and object. The image becomes a sign for a self. Once we get to this stage of the symbolic (the mirror image is a symbol for the self), we can never go back to the state where we were a unified self, where there was no symbol separate from the self. Lacan uses the notion of the Ego-Ideal to describe the memory of the state before our creation as a subject where the child and the image were the same, where there was no Other. This is a state of delight and one which we will always desire. Thus, we constantly try to fill in the gap of our fractured ego.

The mirror stage creates the division between the whole person who we see in the mirror and the fractured person we are. This gap between a person "broken up into little pieces" and our united Ego-Ideal is a gap of uncertainty and displeasure where we are both subject and object. So we are constantly on a search to fill this gap to find the delight of being whole. Images of the Other are important because our fractured identity made through difference also seeks the unification that is perceived in that difference (the Other is seen as whole and different from us with our fragmented egos and therefore must not have a fragmented ego). Our perception of the self depends on what images we use to fill in this lack.

We depend on the existence of the Other to fill in the gap of our desires, to create, if only for a moment, the wholeness before our subjectivity, before there was an Other. How this relates to ads and Otherness can be explained by the importance of the gaze, or more specifically, the image of the Other. Images constitute the self. Images of the literal Other create both a separation because it is through that difference that we are constituted but also as we look toward the Other, it is with the desire of being a unified self. So we depend on the Other both to create the self through difference and somehow to fill up the gap created by our subjectivity because the Other represents this unified self we have lost. We look to ads with their commodities and images of Otherness to constitute the self and somehow fill in the gap between our fractured identity and the ego-ideal.