Strength of research into infant-caregiver interactions
(P) used well controlled procedures
(E) This is because interactions between infants and their caregivers are usually filmed, often from multiple angles, meaning very fine details can be recorded and analysed later.
(E) Also, babies don't know they are being observed, so their behaviour does not change in response to observation.
(L) This is a strength of this line in research because it means that studies are high in validity.