Final answer:
The statement that phonetic or mental representations of speech are stabilized by the age of 5-7 is false; language development is a continuous process that keeps evolving past this age range.
Step-by-step explanation:
The phonetic or mental representations of speech being stabilized by the age of 5-7 is a topic related to language development and cognitive psychology. Early language acquisition research suggests that children start to discern phonemes within the first year of life and are sensitive to the phonemes present in their environment. By age five, children engage in complex activities involving language and cognitive skills, such as having conversations, recognizing letters and words, and understanding humor in jokes. However, the notion that phonetic or mental representations are fully stabilized by the age of 5-7 is somewhat misleading. While significant development surely occurs by this age, language acquisition and refinement is a continuous process that extends beyond this range. Therefore, the statement is False.