Final answer:
Failure to achieve developmental tasks in an infant's stage of development can lead to negative outcomes such as learning disabilities, behavioral problems, and lower IQ later in life.
Step-by-step explanation:
A lack of achievement of developmental tasks in an infant's stage of development can result in developmental delays. In the case of the 1-year-old infant mentioned, failure to achieve the tasks of their developmental stage can lead to negative outcomes such as learning disabilities, behavioral problems, and lower IQ later in life. The impacts of lead exposure in infancy and toddlerhood, for example, can affect the brain's development and result in irreversible effects on the nervous system.