In the book Jeffery A. Gray, Consciousness: Creeping up on the Hard Problem there was a discussion on whether an infant has conscious experience.
p. 119 “A mother is normally in no doubt that a cry of pain is a reliable sign that her infant is consciously experiencing pain; but many scientists and philosophers have grave doubts on the score. (So grave, indeed, that some of the more radical opponents of experiments with animals reckon that it would be ethically sounder to work with human infants – a curious opinion that I do not share).”
Then Jeffery Gray describes experiments on joint attention (according to Peter Hobson, The Cradle of Thought) that show that a twelve-month-old baby has conscious visual experience.
I have searched in Internet and have found on http://infancyresearch.com/ a paper
Striano, T. & Stahl, D. (2005). Sensitivity to triadic attention in early infancy. Developmental Science, 8(4), 333-343.
http://infancyresearch.com/PDFs/2005_SensitivitytotriadicattentioninearlyinfancyDevelopmentalScience.pdf
“The findings from Study 2 showed that both alternating visual attention and positive affect are aspects of joint attention to which 3- to 9-month-old infants are sensitive.”