Mother-Baby Study - Observational

Mother participates in bonding activity with infant at ages 1, 3, and 6 months

Researcher elicits distress in the infant (sequence of unswaddling, pacifier removal, and arm restraint), followed by delivery of oral sucrose in one condition and water in other condition

Researcher gives infant opportunity to suck from two bottles, one containing sucrose and one plain water at infant ages 1, 3, and 6 months

Mother feeds infant on four counterbalanced days at infant ages 1, 3, and 6 months crossing two conditions: (1) regular size nipple versus smaller aperture nipple ('challenging') and (2) providing social interaction while feeding versus not.

Mother feeds infant on four counterbalanced days at infant ages 1, 3, and 6 months crossing two conditions: (1) offering a bottle feeding ad lib for 3 hours versus offering a bottle feeding every hour for 3 hours; (2) providing social interaction while feeding versus not.

When mother indicates infant is hungry, she presents the infant the bottle but withholds feeding for 5 minutes, feeds for one minute, withholds feeding for 30 seconds, and then resumes feeding. She does so under two conditions (providing social interaction during feeding versus not) on two counterbalanced days at infant ages 1, 3, and 6 months.