Hissing is also a vocalization associated with either offensive or defensive aggression. They are usually accompanied by a postural display intended to have a visual effect on the perceived threat. Cats hiss when they are startled, scared, angry, or in pain, and also to scare off intruders into their territory. If the hiss and growl warning does not remove the threat, an attack by the cat may follow. Kittens as young as two to three weeks will potentially hiss when first picked up by a human.