Schaffer and Emerson study procedure
1. 60 babies from Glasgow, most from working-class families
2. Babies and their mothers were visited at home every month for a year and at 18 months
3. Separation anxiety measured by asking mothers about their children's behaviour during everyday separations (e.g. adult leaving the room)
4. Stranger anxiety was measured by asking mothers questions about their children's anxiety response to unfamiliar adults