Apeil 10, 1914] 



SCIENCE 



549 



Abnormal £md normal chicks were placed on 

 stands from 10.7 cm. to 179 em. above the box in 

 which they were kept and the height at which 

 they refused to jump recorded. The abnormal 

 chicks jumped from greater heights. 

 ■ To determine the difference in rapidity of learn- 

 ing three mazes were used, one a straight path 

 blind at one end, one a simple choice maze with 

 the exit on the left side, the third the Yerkes 

 apparatus. 



The chicks were given ten trials each in each of 

 the first two mazes and the time taken to find the 

 exit recorded. Abnormal chicks learned their way 

 out of the first maze almost as swiftly as normal 

 ehicks, but learned their way out of the second 

 much more slowly, making many wrong choices. 

 Two failed to learn the way out. 



With the Yerkes maze the number of trials 

 taken before the chick made ten consecutive right 

 •hoices was recorded. The exit was on the right 

 Bide. The normal chicks learned the way to the 

 •xit in 8 trials, the abnormal in from 23 to 45 

 trials. 



Two Factors wliicli Influence Economical Learn- 

 ing: Edwaed K. Strong, Jr. 

 The paper presented the results of a number of 

 experiments in the field of advertising and dis- 

 cussed their bearing upon studies that have been 

 made in the field of economical learning. 



The general conclusions were as follows: (1) 

 Repetitions of advertisements a few minutes apart 

 6r a week apart are about equal in efficiency when 

 tested four months later, but both such intervals 

 are superior to repetitions a month apart. On 

 the basis of all the work in this field, it would 

 seem that the optimum interval for repetition is 

 one day. (2) The more impressions made at one 

 time, the less is the permanent retention of any 

 one of them. This is probably due to the effect 

 of retroactive inhibition. (3) In any situation 

 when both length of interval and the number of 

 impressions to be made at any one time are con- 

 eerned, it should be borne in mind that the sec- 

 ond factor is far more important than the first. 

 This means that further work should be directed 

 more particularly to a better understanding of 

 how many impressions can be made to advantage 

 at any one time, rather than to the proper inter- 

 val of time between their successive presentations. 

 Published in the Journal of Philosophy, Psychol- 

 ogy and Scientific Methods, Vol. XI., No. 5, Feb- 

 ruary 26, 1914. 



Psychological Characteristics of the Africom 



Negro: Jerome Dowd. 



Professor Dowd divided Africa into economic 

 zones, and contrasted the characteristics of the 

 people of each zone. 



' ' The instinct of flight is very pronounced in 

 the banana zone. Nature is here manifested in a 

 very violent form — exciting terror and gross super- 

 stitions. It is a zone of idols, fetichism, witch- 

 craft and the magic-doctor. In the agricultural 

 zones nature is less antagonistic, and the struggle 

 for existence more severe, requiring more reason 

 and courage. Here the emotion of fear is 

 less pronounced^ — the number of idols diminishes, 

 and the magic-doctor uses less hocus pocus and 

 more medical art. In the cattle zone, where na- 

 ture is still less violent and terrifying and the 

 climate and other conditions more conducive to 

 action, we observe still less fear among the people, 

 less use of idols, witchcraft and magic-doctors. 



' ' The instinct of pugnacity is weak in the banana 

 zone because of the intensity of the feeling of 

 fear. It is more pronounced in the agricultural 

 zones, and very much so in the pastoral zones 

 where the conditions provoke chronic warfare. 

 This instinct is of great value to any race — since, 

 under peaceful conditions, it is carried over into 

 all lines of activity. Instead of the war of fire 

 and sword, we have the war of tools, machinery, 

 commodities and ideas. From the games played 

 by children and adults up to the rivalry of na- 

 tions for intellectual and moral supremacy we see 

 the play of this primitive instinct. The nations 

 that now occupy the highest rank in the industrial 

 rank in intellectual and moral development are 

 precisely those which have gone through the 

 fiercest and most prolonged era of warfare. 



' ' The gregarious instinct is remarkably developed 

 in the central regions of Africa where the bounty 

 of nature permits of the living together of large 

 groups. It is not quite so well developed in the 

 other zones, although it is everywhere very char- 

 acteristic of the African Negro. In the lower 

 stages of society this instinct serves the useful 

 purpose of insuring to aggregations of people the 

 development of laws and institutions. McDougall 

 believes that this instinct is less important for 

 civilized people and often produces anomalous 

 and even injurious social consequences in large 

 cities. According to Giddings and McDougall, this 

 instinct is due to consciousness of kind. I believe, 

 however, that people are attracted to each other 

 by unlikeness, and the so-called instinct of gre- 



