Sandy has a huge crush on casey. when he is nearby, sandy doesn't pay attention to anything or anyone else. psychologist donald broadbent explained that we selectively attend to the most important information in this model, which he developed.

The answer in the given statement above is filter theory. It is what Sandy is portraying above for filter theory involves in mating selection and dating. This theory makes a person have the selection which is only limited for the individual in having his or her mate. It could be seen above as Sandy does not see anybody else but Casey for she does not pay attention to anyone but her.