The first impression is made by the brain. In the first moment it projects everything into the subject that is similar to it.

The next impressions may already be different. But often the first impression is established and directly determines the view and your own behaviour from this perspective towards the subject.

It particularly determines the emotional attitudes and sees e.g. another person from that point of view. A change is often difficult, also because the brain has already stored it in this form.

It looks different with factual circumstances. First, there are usually not so many feelings involved, and second, if there are new circumstances, you have to adapt to them. This is more a forehead brain task.