ANIMAL BEHAVIOR 851 



tendon or the flash of light) this failure is evidence of an abnormal 

 condition of the reaction. 



Reflexes terminating in action patterns of smooth muscles and 

 glands also occur. The saliva starts to flow when the odor of food 

 assails the nostrils. It has been conventional to describe reflexes as 

 unconscious reactions, but as a matter of fact there are no such reflexes 

 in the normal human being, and apparently none in other vertebrate 

 animals. Striking a blow on the patellar tendon, for example, does 

 not merely produce a reaction terminating in contraction of the quad- 

 riceps muscle which propels the lower leg forward. Effects are demon- 

 strable in other parts of the body and included in the total response 

 is the perceptional awareness of the blow. Expectant attention of the 

 blow and attention to other stimuli affect the leg movement. The pre- 

 dictability and brevity of the reflex are only relative. The important 

 difference between a reflex and a perceptional reaction is that the re- 

 flex would occur and be still more predictable, even if the animal were 

 so mutilated that the neural patterns, aside from the parts most di- 

 rectly affected, were eliminated. For example, if by accident the spinal 

 cord of a person is broken above the lumbar region, and several 

 months are allowed for the effects of shock to disappear, the knee jerk 

 may be elicited and is more pronounced and more uniform for a given 

 force of blow than before. The person in such a condition does not 

 perceive the blow unless he is allowed to see it or hear it, and he can- 

 not perceive the jerk of the leg except by sight. The discrimination of 

 the lower part of the spinal cord, through which the essential part of 

 the reflex transit occurs from the upper part of the cord and brain, 

 prevents the stimulus from affecting more than the leg muscle. Similar 

 results can be obtained from dogs and cats by experimental severing 

 of the cord at proper levels. In these cases the reflex becomes a real 

 unconscious reaction, which it is not in the normal animal, and it is 

 unconscious because it is restricted to a part of the organism. 



Chain Reflex Behavior 



Chain reflex behavior in animals is also often called instinctive be- 

 havior. Watson defines instinct as a series of concatenated reflexes 

 which unfold serially upon proper stimulation. In insects and other 

 animals, we find that reflexes often occur in series ; one directly called 

 out by some appropriate stimulus, itself becomes the cause of another 

 which follows it, and so on through a longer or shorter series. These 



