DELAYED REACTION 63 



second problem. During the learning series, the light stimulus 

 acquires the power of releasing muscular activity applied in a 

 certain direction. Just what direction this shall be is deter- 

 mined by the spatial location of the light. A significant mean- 

 ing here attaches to the object ve stimulus, i.e., the light plus 

 the definite location. (By the term meaning, I imply nothing 

 more than the fact that a certain stimulus evokes a certain 

 reaction under conditions that are not usually described as 

 involving mere habitual or reflex activities.) 



As soon as the problem shifts to a choice of one of three sim- 

 ilar boxes, i.e., as soon as a stage is reached where the deter- 

 mining stimuli are absent at the moment of reaction, then it is 

 necessary, I assume, if the reactions are to succeed, that the 

 subject develop substitutes which shall take the place of those 

 stimuli as carriers of the needed meanings. In other words, the 

 substitutes must fulfill the function of the previous stimuli in 

 arousing the three appropriate movements. The substitutes 

 may secure this power either through association with the light 

 during the learning series, or during the delayed reaction tests 

 themselves through a process of trial and error. In view of the 

 fact that delayed reactions did succeed under the present con- 

 ditions, there can be no question as to the existence of the sub- 

 stitutes. Our next problem is that of determining their nature. 



The substitutes or cues that determined the subject's reac- 

 tions may theoretically have arisen either within or without 

 the organism. We shall consider the latter first. 



A. Substitutes Derived from the External Environment. — Under 

 this heading, we shall consider two possibilities: (a) Were 

 there three simultaneously present objective cues that may 

 have served to determine the subject's reactions? and (b) were 

 there three objective cues that varied from trial to trial with 

 the position of the light which may have determined the reac- 

 tions after the light was turned oft'? In any case there must 

 be two or three cues each determining one of three reactions. 

 We shall consider the possibilities in the above order. 



(a) Simultaneously present objective cues. — Although every 

 effort was made to secure uniformity in the visual appearance 

 of the three light boxes, they differed at least in spatial position 

 and in the nature of the part of the experimental room visible 

 above the walls of the apparatus. In addition there were pos- 



