<p>While there is a single UC application, the procedures, rules and admissions process itself are exceedingly different among the campuses. Even in a campus, different colleges have their own rules and thresholds. </p>
<p>The answer above appears to be oriented to UC Berkeley, where the College of Letters and Sciences does not admit students to particular majors, instead expecting them to declare a major somewhere around the end of second year or beginning of third. However, applying as an engineering major instead of as a psychology major puts you in a different college and under stricter admissions standards. Thus, the major you list does have an impact in most cases.</p>