In developmental psychology, if an infant is unresponsive when you tap her foot, which of the following reflexes is most likely absent?

• A. Palmar grasp reflex
• B. Rooting reflex
• C. Moro reflex
• D. Babinski reflex

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the context of the problem, which involves identifying a specific reflex in infants based on their response to a physical stimulus—in this case, tapping the foot.
2. Step 2: Review the definitions and typical responses of the listed reflexes: Palmar grasp reflex (grasping with the hand), Rooting reflex (turning head toward touch on cheek), Moro reflex (startle response with arms flinging out), and Babinski reflex (toes fan out when the sole of the foot is stroked or tapped).
3. Step 3: Recognize that the Babinski reflex is specifically tested by tapping or stroking the sole of the foot, and a normal response is the fanning of the toes, indicating neurological function.
4. Step 4: Analyze the problem statement that the infant is unresponsive to tapping the foot, which suggests the absence of the Babinski reflex rather than the other reflexes that involve different stimuli and responses.
5. Step 5: Conclude that the reflex most likely absent when an infant does not respond to tapping the foot is the Babinski reflex, as it directly relates to that specific stimulus and response.