The Mere Ownership Effect, also known as the "possession effect", is a psychological phenomenon that describes the human tendency to value things that they own or have in their possession more highly than comparable things that they do not own. This effect manifests itself in various aspects of human behaviour and has an impact on our decision-making, our purchasing behaviour and even our social interactions.

One of the most remarkable manifestations of the Mere Ownership Effect can be observed in the world of consumption. People tend to value the products or items they own more favourably, regardless of their actual quality or usefulness. This can lead to a tendency to hoard our own possessions and acquire new things, even if they are not really necessary.

Another interesting feature of this phenomenon is its effect on social interactions. When people feel they have established an emotional or personal connection to an object, they tend to present it more favourably to others and see it as part of their identity. This can lead to interesting social dynamics where possessions serve as status symbols or identity markers.

Psychologists and behavioural researchers have intensively studied the Mere Ownership Effect and developed various theories to explain its causes. One approach argues that ownership of an object conveys a sense of control and autonomy, which in turn leads to a more positive evaluation. Another approach views ownership as a kind of "psychological ownership", in which people develop an emotional attachment to their possessions.

In the world of marketing and advertising, the Mere Ownership Effect is often used to promote customer loyalty and sales promotion. Companies rely on strategies that give customers the feeling that they already own products or services, be it through test phases, free samples or personalised experiences.

In summary, the Mere Ownership Effect is an interesting and complex phenomenon that influences our behaviour and decisions in many ways. It illustrates the extent to which ownership and emotional attachment to things can influence our perception and judgement.