Essentially what it is is a reaction to something new that appears in your surroundings, be it a noise (such as someone saying your name), something visual, etc.
In class we were using the cocktail party effect as an example, talking about how you can orient your attention, aka your cognitive "resources," onto a specific person or group of people talking within a crowded room, but then when someone says your name somewhere across the room--Aha! The novel stimulus, inciting the orienting response--your attention shifts to whoever said your name, trying to figure out who said it, if they are getting your attention or gossiping about you, what might they be gossiping about...yada yada yada...and suddenly your focus has shifted completely from the original conversation you were involved in.
While discussing this in class, I was trying to think of other relevant examples and it occurred to me that I was picturing my cat walking through the door of the classroom. As in, Dibbs the cat is my novel stimulus that incites an orienting response in me.
People, I have a problem. Someone faints, you wave ammonia under his nose, he comes to. Bailey starts to lose focus, Dibby appears anywhere in her peripheral vision, and her attention is instantly reoriented to the tabby cat.
(If you care): The only reason this goes against the characteristics of the orienting response is that over time within a specific context, as you become accustomed to a stimulus you don't react to it quite as quickly. So, if your name is John and there are lots of Johns at the party, after a while you'll stop paying attention if you hear someone say "John." That said, you would think that after seeing Dibbs thousands of times I would no longer view him as novel.
It was both comical and disturbing to me as I realized this during our discussion today. I almost raised my hand to share it with the class, but I felt that would be too public and embarrassing.
So I took it to my blog. ;)