“…first signs of "truly intelligent" behavior are manifested through intentional coordination of two independent schemata; final (end) and transitional (means). Piaget's framework has often been applied to nonhuman animals (e.g., Antinucci, 1989;Doré & Dumas, 1987;Parker & McKinney, 1999;Pepperberg, 2002;Vauclair, 2012), one reason why string-pulling tests are so common in animal cognition (Chevalier-Skolnikoff, 1982, 1983Dumas & Doré, 1991;Frank & Frank, 1985;Hallock & Worobey, 1984; Older animals often perform better because they are more cognitively developed and less playful (Davis, Lovelace, & McKenna, 1964;Mason & Harlow, 1961), although juveniles might be more successful because they can be more persistent (Vince, 1958(Vince, , 1961.…”