Cognitive psychology studies human cognition, focusing on mental processes such as thinking, understanding, decision-making, and problem-solving. The cognitive revolution of the 1950s shifted the focus from merely observing human behavior to exploring the human mind. For example, cognitive psychologists study how people solve math problems, how an individual recognizes a friend's face in a crowded room or decides to carry an umbrella outside on a cloudy day. Swiss cognitive psychologist Jean Piaget noted that children perceive the world differently from adults. He discovered that children often believe the amount of water changes when it's poured into a taller glass because they focus more on the height than the actual volume. Cognitive psychology uses techniques like MRI and fMRI to study how brain activities support cognitive functions such as perception and memory. This approach has profoundly influenced various disciplines, including linguistics, computer science, and neuroscience.