 The idea of instinct in classical ethology was strongly criticized by several North American psychologists including Theodore C. Schneirla (1952; 1963; 1966), Howard Moltz (1960; 1965), and most famously by Schneirla’s student Daniel S. Lehrman in ‘A critique of Konrad Lorenz’s theory of instinctive behavior’ (1953). Lehrman objected to ethologists’ resurrection of the innateness concept on both empirical and theoretical grounds. Empirically, Lehrman documented the role of environmental factors in the development of species-typical behavior patterns, drawing on many existing studies, including some by Kuo. These experiments revealed that certain prototypical fixed action patterns depend on environmental feedback for their development. This is true despite the fact that such behaviors are species-typical and present in animals that were raised in isolation. For Lehrman, such evidence undermined the attempt to distinguish innate from acquired behavior: