LITERATURE FOR 1915 ON THE BEHAVIOR OF 



VERTEBRATES 



STELLA B. VINCENT 



Chicago Normal College 



SOUND 



Mammals. — The auditory sensitivity of the white rat still 

 continues to engage the attention of Hunter (13). The work 

 here reported has its chief interest in the substantiation of his 

 previous experimentation through the introduction of many 

 and varied controls. The method and the apparatus was de- 

 scribed last year. The rats failed to show, through any be- 

 havior, discrimination between the sound of a tuning fork 896 

 dv and the absence of the sound in 650 trials. Rats trained to 

 react to a Galton whistle tone of 3906.07 dv would not react to 

 a tuning fork 1152 dv plus 1280 dv or to the fork 1280 dv when 

 each of these were substituted for the standard stimulus. The 

 author says: ' When a whistle of the same pitch was sounded 

 in an adjoining room, so that the distance probably eliminated 

 the noise factor, the rats failed; although they made a signifi- 

 cantly larger per cent of correct reactions when the standard 

 stimulus was decreased in intensity to match the intensity of 

 the distant whistle. Further, these same rats reacted properly 

 when either of the following noises were substituted for the 

 standard whistle: (a) the rush of air through the whistle; (b) 

 sound of rush of air made with lips ; (c) clapping of hands. The 

 rats reacted successfully to 1280 dv on the standard whistle but 

 failed when the same pitch was sounded on the tuning fork." 



He concludes "(1) There is a practical insensitivity to many 

 pitches in the lower region of the scale for the white rat. This 

 apparently goes along with a sensitivity to noise of the same 

 predominant pitch. 



"(2) Differences in total complexity and intensity may be con- 

 siderable without making discrimination possible. 



