PROBLEM ^J Hoiv Does the Behavior of Complex Animals 



Differ from That of Simpler Forms? 



The nervous system and behavior. You 



now know that the behavior of a species 

 of animal depends in many ways on the 

 kind of nervous svstem it has. Some ani- 

 mals have complex brains made up of 

 billions of neurons with enormous num- 

 bers of connections through end brushes 

 and dendrites; their behavior is complex. 

 If the brain is simple in structure, the be- 

 havior is simple. 



But no one has been able to explain 

 what goes on in the neurons of human 

 beings. No one has been able to say what 

 changes take place in man's neurons 

 when he thinks or remembers something 

 that happened a year ago or feels sorry 

 for someone. We are fairly sure that 

 neurons are involved in these forms of 

 behavior but we don't know how. 



In spite of our ignorance of the part 

 played by neurons a great deal has been 

 learned about human behavior bv obser- 

 vation and experiment. Some of the im- 

 portant ideas developed by psychologists 

 (sy-kol'o-jists), people who are students 

 of human behavior, will be presented 

 here. 



Our behavior is extraordinarilv com- 

 plex. The behavior of a simple animal is 

 difficult to understand. The behavior of 

 an animal with a brain is almost too com- 

 plex to describe, let alone explain. There 



are so many stinuili being received, so 

 many responses being made, so many 

 neurons taking part all at the same time, 

 that describing each act as a separate act 

 gives quite the wrong picture. In de- 

 scribing your behavior at this moment 

 one might say that you are reading this 

 page. But what a false impression that 

 would give of what is really going on in 

 you! In the first place that one act of 

 reading involves a great many other acts: 

 contracting many eye muscles to move 

 your eyes across the page, probably 

 holding down of the page by the muscles 

 of y^our arm, perhaps the holding of a 

 pencil, seeing the letters, interpreting 

 the words, understanding the meaning. 

 And there are dozens of other responses 

 that you are Qivino- at this moment that 

 have no direct connection with your 

 reading. You are contracting muscles 

 which keep your body in an upright po- 

 sition, you are performing all the inter- 

 nal reflexes, such as breathing, heart- 

 beat, and digestion. You may be hearing 

 a truck rattling outside the window, feel 

 a breeze on your face, smell the food be- 

 ing prepared in the kitchen, feel a 

 r\\ inge in an aching tooth, and so on in- 

 definitely. There is no limit to the com- 

 plexity of the behavior in a higher 

 animal. 



