Final answer:
Schaffer & Emerson's study on infant attachment is notable for its longitudinal approach but criticized for limited generalizability due to a small, culturally homogeneous sample.
Step-by-step explanation:
Schaffer & Emerson's 1964 study on infant attachment, emphasizing stages of attachment development, greatly contributed to attachment theory. However, it faced methodological challenges. The study's small sample size, mainly focused on working-class families, limits generalizability.
Additionally, reliance on mothers' reports may introduce bias. Observations were subjective, affecting reliability. Yet, the study's longitudinal design provided valuable insights into attachment dynamics. Recognizing these limitations is crucial for a comprehensive evaluation, acknowledging both its strengths in pioneering attachment research and the need for cautious interpretation due to inherent methodological constraints.