Issues in Sensorimotor Stage of Cognitive Development

An 8-month-old infant discovers that shaking a toy rattle produces a sound. The infant then begins to shake the rattle intentionally and repeatedly, smiling each time the sound is made. This behavior is a classic example of which key development during the first stage of cognitive growth?

An 8-month-old infant is playing with a small toy car. Their parent covers the car with a blanket. The infant, after a moment of surprise, lifts the blanket to retrieve the car. Which cognitive accomplishment, characteristic of this stage of development, is the infant demonstrating?