Design historian Pat Kirkham has written the definitive article "Reassessing the Saul Bass and Alfred Hitchcock Collaboration."
Ms. Kirkham's exceptionally well researched and written January 11th, 2012 article for the Design Observer's Observatory webpage includes the following:
"Film director Billy Wilder, who knew both Bass’s and Hitchcock’s work inside out, had little patience with those who could not see the difference between the overall style of the film and that of the shower scene. He told [Ms. Kirkham in a 1994 interview], “Like most people in Hollywood you knew who did what if you were in the industry, especially if great stuff was involved. Everybody talked about that scene. Right from the beginning I understood that Saul did it. Everybody knew. Everybody knew Saul was brilliant. Who questioned it until those remarks of Hitchcock? . . . You only have to look at the sequence and look at the film and think. Think for one minute. You see the shower scene and you see it is not at all like Mr. Hitchcock — King of the Long Shot.”"