What did Alfred Hitchcock use as blood in the film "Psycho"?

Alfred Hitchcock used chocolate syrup as blood in the film Psycho because it provided a stark contrast against the black and white film. The light consistency and dark color of the syrup showed up well on the black and white film, creating a realistic and dramatic effect that would have been challenging to achieve using real blood or other substitutes. Additionally, chocolate syrup was readily available and cost-effective, making it a practical choice for the production.