<p>At my HS foreign language usually conflicts with advanced science
APs in the Junior year. So a number of students leave out
the foreign language. In Top 25 schools below the top 5 it
does not seem to matter whether the student does 3 or 4 years.</p>
<p>At top 5 schools, it is clear that demonstrated proficiency in a foreign
language is something that makes a difference. Having 4 yrs does not
get you admitted; not having the qualification on the other hand hurts
the applicant.</p>
<p>OP, it does not seem to be a myth based on anectodal evidence at my HS.
In '08, I applied and was admitted to the specific top 10 schools I applied to
(I did have 4 yrs of a foreign language in HS leading to an AP level).
In '09 a student with a very simialr profile minus foreign language
(had only 2 yrs) applied to and was waitlisted/rejected at all the
top 10 schools he applied to. Sure, there could have been other
reasons. His lack of foreign language proficiency did seem to
stick out significantly.</p>
<p>Also I have noticed that those students who attain proficiency in
multiple foreign langauges are admitted routinely from my HS
at Harvard. (Asian-origin students studying their own language do
not fall in this category though)</p>