Final answer:
In middle adulthood, there are changes in information processing, with a decline in fluid intelligence while crystallized intelligence tends to remain steady or improve. Engaging in mentally and physically stimulating activities can delay cognitive decline.
Step-by-step explanation:
In middle adulthood, some areas of information processing undergo changes. While crystallized intelligence (information, skills, and strategies gained through experience) tends to remain steady and may even improve, there is a decline in fluid intelligence (information processing abilities, reasoning, and memory).
As individuals age, their processing speed becomes slower. However, engaging in mentally and physically stimulating activities can help delay cognitive decline and reduce the risk of mild cognitive impairment and dementia.