262 ARTHUR C. WALTON 



ment. Later this method was dropped to avoid giving visual 

 or olfactory cues as to the position of the reward. The food 

 was now thrown to the dog after the completion of the correct 

 reaction, but the dog developed a lax habit of only partially 

 completing a reaction. He would approach only to the en- 

 trance of the food compartment and then await the reward. 

 To avoid this result a new method of giving the food reward 

 was introduced. One experimenter stood outside of the door 

 (D — Fig. 1) watching the dog's actions through a peephole and 

 entered the room with the reward only after the animal had 

 traversed the entire length of the correct food compartment. 



The experiments were given under varying conditions and 

 the results are recorded separately for each type under the 

 following heads: 



Condition "A" — Light Stimulus — Operator in view of dog. 

 Release box faced compartments all the time. Used in the 

 training experiments with Two and Three Lights. 



"Al" — Food placed in the compartment at the beginning 

 of the trial. 



"A2" — Food thrown to compartment after a correct reaction. 



Condition "B" — Operators out of sight of dog until after re- 

 action was complete. Release box faced the compartments 

 during stimulus and delay periods. Used in delay experiments 

 with Two and Three Lights. 



"Bl" — Food placed in compartment at outset of trial. 



"B2" — Food thrown to compartment after a correct reaction. 



Condition "C" — Light Stimulus — Operator out of sight of dog 

 until after reaction was complete. Release box turned 90 

 degrees during delay period. Used in "Two, Three and Four 

 Light Experiments." 



"CI" — Food placed in compartment at outset of trial. 



"C2" — Food thrown to compartment after correct reaction. 



"C3" — Operator out of room until reaction is complete.. 

 Food given after correct reaction. 



Condition "AD" — Used in 'Two Light" experiments. Dis- 

 turbing stimuli (Olfactory, Auditory and Visual) given during 

 delay period. Release box faced compartments during entire 

 reaction. Food given after correct reaction. 



Condition "CD" — Used in 'Two Light" experiments. Dis- 

 turbing stimuli (Olfactory, Auditory and Visual) given during 



