106 EUPHA FOLEY TUGMAN 



(f) Effect of 48 hour interval between successive series. Table 

 VIII shows the effect of 48 hours interval between successive 

 series. As stated before, one series per day was given each bird 

 except on Sunday and an occasional holiday. So this table 

 gives the percentages of error for the series on the day preceding 

 the holiday and the percentage of error for the day succeeding 

 the holiday. In a few cases the position of the variable was 

 changed over the holiday and so these cases were not considered. 



For Male V the average percentage of error for Saturday and 

 days preceding holidays is 26.97, while for the day following the 

 48 hours' rest, his percentage of error is 28.8 or an increase of 

 1.83%. For Female V the average percent of error for Satur- 

 day, etc., is 15.81% and for Monday the average is 21.35%, 

 which shows an increase of 5.54%. Male V has an average 

 per cent of error on Saturday of 20.91% and on Mondays an 

 average per cent of error of 21.91%, which is an increase of just 

 one per cent. Female VI has an average per cent of error on 

 Saturdays of 15.73% while on Mondays her average per cent 

 of error is 18.73%, which shows an increase of three per cent. 



To recapitulate: For Male VI Mondays show an increased 

 percentage of error of 1.83%; Female V, 5.54%; Male V, 1%; 

 and Female VI, 3%. Thus each of the birds shows the effect 

 of an extra 24-hour interval between two series, by an increase 

 in the average percentage of error for the following day. 



(g) Persistence of stimulation. It has been the experimenter's 

 observation that the sparrows do not retain the effects of stimu- 

 lation very long at a time. Frequently, as stated before, the 

 birds would get the position habit of alternating from one side 

 to the other. One day, when this occurred, the series was inter- 

 rupted as the experimenter was called out of the room. Upon 

 returning to the experiment the observer noticed that the bird 

 hesitated before choosing between the lights. He then chose 

 the same light as in the test preceding the interruption. Then 

 in the following tests he alternated from one side to the other 

 as before. So the alternation was in regular order with the ex- 

 ception of the one break due to the interruption. After that 

 when a bird acquired the habit of alternating from one side to 

 the other, the observer would stop the experiment several minutes. 

 In practically every case the bird would hesitate in mak- 

 ing a choice in the test following the interruption and usually 



