Conversation so far:
what happened with tippi hedren in 1961?
On October 13, 1961, she received a call from an agent who told her a producer was interested in working with her.
who called?
it was Alfred Hitchcock.
then what happened?
she agreed to sign a seven-year contract.
what movies did they make together?
and was asked by Hitchcock to play the leading role in his upcoming film The Birds.
.
what else did she do?
Hitchcock put Hedren through an extensive color screen test that lasted two days and cost $25,000, doing scenes from his previous films.

Question: what was the previous films?
Self-contained rewrite: What were the previous films of  Alfred Hitchcock?