 A second general pattern is that such ambiguity was no barrier to the sheer volume of studies claiming to identify instincts. Indeed, it might even be the case that lack of precision in the meaning of this term fostered the growth of the instinct industry in late 19th and early 20th century. A third general pattern is the persistent complaint that instinct theorists ignore early or subtle opportunities for learning. Wallace criticized Darwin for failing to consider the influence of experience in early development. The same objection can be found in Kuo’s criticism of instinct theory. Lehrman and his fellow critics likewise noted the failure of ethologists to consider possible influences of experience on development.