What determines consumers’ demand?

Demand and supply are the two probably most important concepts in economics. Demand is determined by consumers’ preference and price. In the majority of cases, when a product’s price goes down, the demand for this product will increase. However, what determines if a person demands the product at a given price is this person’s preference. There are many factors determining a person’s preference and people’s preferences vary across different individuals. Often these factors can be very personal. For example, if someone wants to buy a pair of headphones, the sound quality provided by a pair of headphones is not necessarily consistent, as the performance may vary based on what song the user is listening to, therefore how much this person is willing to buy a particular pair of headphones can depend on his or her preference of music. Moreover, his or her preference may also be influenced by his or her work. If his or her work requires a lot of travelling, he or she may want a pair of noise cancelling headphones and is likely to value noise cancelling headphones mor than those who do not travel so often.
Therefore, a person’s preference is based on his or her previous experience and expectation about the future. Let’s focus on how a person forms expectation. People generally form their expectation based on what they see at the moment, what they have learned and experienced. What they have learned and experienced can also be seen their experience so far. What they see at the moment depends on their accessibility to information. A person’s accessibility to information is based on their network connections, jobs. However, these elements (even including experience) may depend on people’s family and background.
If the hypotheses are true, then we can use the population characteristics to model the population preference as a whole, due to all factors are correlated with people’s background and family, which are known objectively.