Gottlieb's major contribution to the field of psychology was his theory of probabilistic epigenesis, which explains that there is no predetermined path to trait development.
[1] in 1982 he was an Excellence Foundation Professor and Head of the Department of Psychology at the university of North Carolina at Greensboro.
The developmental age that Gottlieb measured characterized this "critical period" with an "appropriate" independent variable.
[4] Gottlieb continued his research involving birds by depriving mallard ducks of auditory sensory stimulation experienced in normal development.
[1] Gottlieb's major contribution to psychology was his theory of probabilistic epigenesis, which states that behavioral development does not have a predetermined course.