Complex sentence: In January 1971 doctors administered a Gesell Developmental Evaluation and found Genie to be at the developmental level of a 1--3 year old, noting that she was already showing substantial disparities in different areas of her development.
Split into simpler sentences: In January 1971 doctors administered a Gesell Developmental Evaluation, and found Genie to be at the developmental level of a 1--3 year old. At that time, they noted she was already showing substantial disparities in different areas of her development.