Conversation so far:
What happened in 1961 for Tippi Hedren?
On October 13, 1961, she received a call from an agent who told her a producer was interested in working with her.
who called Tippi Hedren?
An agent who told her a producer was interested in working with her.
then what happened after the agent told Tippi Hedren a producer was interested in working with her?
When she was told it was Alfred Hitchcock who saw her in a commercial for a diet drink called Sego, she agreed to sign a seven-year contract.
what movies did Tippi Hedren and Alfred Hitchcock make together?
The Birds (1963), Marnie (1964)
what else did Tippi Hedren do for Alfred Hitchcock besides Discovery, The Birds, and Marnie?
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 was the previous films from which Alfred Hitchcock had Tippi Hedren do during extensive color screen tests?