Final answer:
Mariana, who reacts strongly to unpleasant stimuli, may have a difficult temperament and could be susceptible to colic. Soothing techniques such as swaddling and gentle rocking are often effective for calming such infants.
Step-by-step explanation:
According to the work of developmental psychologists Alexander Thomas and Stella Chess, newborn Mariana, who reacts strongly to unpleasant stimuli, might be displaying early signs of a difficult temperament. Thomas and Chess' research included the categorization of temperaments of children into three basic types: easy, difficult, and slow-to-warm-up. A child like Mariana, who cries a lot and is hard to soothe, similar to the mentioned 18-month-old Brianna, would likely be classified as having a difficult temperament. This means that Mariana could potentially be susceptible to colic and may exhibit behaviors such as frequent crying, difficulty calming down, and possible sleep disturbances.
Soothing methods for infants with a difficult temperament often involve the sense of touch. Well-documented techniques include swaddling, gentle rocking, and the use of pacifiers, which can help calm a distressed newborn, contradicting the option that such an infant is 'unlikely to respond to swaddling'. Neonates, or newborns, with their well-developed sense of touch, typically find comfort in these tactile stimuli.