CONCEPTUAL THOUGHT 165 



as to give the impression that the brain is innately inspired. 

 Language in the human plays a very important part in the 

 thinking process. Words are signs or stimuli which bring to 

 the fore particular learning sets best suited to the solution of 

 a given problem. The human "talks" while he thinks, re- 

 viewing ways of attacking a given situation, and so fixed is 

 this habit that there is a disinclination on the part of some to 

 admit that there can be any conceptual thought without lan- 

 guage. 



That animals other than man can and do use symbols or 

 signs to identify appropriate learning sets has already been 

 brought out, but there remains to describe one more series 

 of studies of apes that should be of interest since the re- 

 sponses approach more closely to the general character of 

 the human than anything thus far reviewed. At the Yale 

 Laboratories of Primate Biology, John Wolfe trained six 

 young chimpanzees to respond to poker chips as symbols or 

 temporary substitutes (like money) for food and other re- 

 wards. Wolfe used a specially built slot machine which au- 

 tomatically delivered one ripe grape each time a poker chip 

 was dropped into the slot. Each of the six individuals was 

 taught how to m.ake what was called the "Chimp-O-Mat" 

 deliver the grape. A six-year-old male. Moos, who possessed 

 strong imitative talents, actually caught on after seeing the 

 experimenter drop just one chip into the machine which, of 

 course, immediately delivered a grape into the food cup. 

 Moos, without hesitation, took a chip which was proffered 

 and dropped it into the slot; then put his hand in the cup and 

 waited for the grape, an unusual but not unique perform- 

 ance. Prior to the beginning of this series, white poker chips 

 had been given to the six chimps as toys. They paid little or 

 no attention to them at the time, but as soon as they learned 

 that they could obtain food with these chips their whole at- 

 titude changed, much as would a group of humans if some 

 objects they thought worthless were suddenly found to be 

 coin of the realm. As the teaching progressed, both poker 



