Describe the three major acquisitions that mark the culmination of the sensorimotor period. What is common to all three acquisitions?

What will be an ideal response?

Three major acquisitions that herald the end of the sensorimotor period are object permanence, deferred imitation, and inner problem-solving. Object permanence refers to the remarkable achievement of coming to behave as if objects and people have a continued existence even when they are not in sight or in hand. Although recent research indicates that the search behaviors Piaget required as evidence of understanding of an object's permanence led to underestimation of actual understanding of object permanence, evidence does indicate that it is not until 18 to 24 months that children show they can mentally represent invisible displacement of objects and inhibit the impulse to search for hidden objects at locations they know are incorrect. Deferred imitation refers to the ability to reproduce behavior observed in another in the absence of the model. It requires the use of a stored memory of the modeled behavior to guide/mediate recreation of the modeled sequence. Although recent research suggests that infants show some evidence of deferred imitation before the latter half of the second year, few can reenact complex behavioral sequences until 18 to 24 months. Inner problem-solving refers to the ability to arrive at a solution to a problem mentally without having to resort to overt trial-and-error activities. Both deferred imitation and inner problem-solving represent remarkable advances over the exercising and accommodation of inborn reflexes of the newborn, allowing for rapid expansion of the behavior repertoire. Common to all three acquisitions is the utilization of internal images, language, or other means of symbolic representation to guide or mediate behavior.