The Mid-Winter Meetings. 189 



At the fifteenth annual meeting of the American Psychological Association, 

 the following papers in the fields of comparative psychology and sense physiology 

 were read : 



The Photography of Ocular Movements. By G. M. Stratton. 



The Rotation of the Eye during Fixation and in Movement. By C. N. McAllister. 



Studies in Binocular Depth Perception. By J. C. Bell. 



Some Results of Experiments on Cerebral Circulation during Sleep. By ]. F. 



Shepard. 



This was a preliminary report on volume reactions during sleep while the sub- 

 ject was lying down. Two subjects were used. For part of the records the influ- 

 ence of movements was eliminated by placing the subject's head in a swing. 



With the first subject, the volume of the brain and of peripheral parts increases 

 as he goes to sleep, and decreases as he awakes. There is often a temporary fall 

 of the brain volume preceding the more marked rise which shows itself as sleep 

 becomes deeper. There is a prominent breathing wave in the records from both 

 brain and periphery. In this wave, the fall in the circulation record very nearly 

 corresponds to an inspiration, the rise to an expiration. Stimuli that disturb but 

 do not awake the subject cause a temporary increase in breathing in both chest 

 and abdomen, a fall of volume of the brain and peripheral parts with comparative 

 elimination of the breathing wave therein. While the subject is sleeping soundly 

 and there are apparently no distinct stimuli acting, one often finds a more or less 

 rhythmic repetition of such changes, analogous to the Traube-Hering wave. 

 There is always some evidence of this wave, and the changes in brain and periphery 

 are always parallel. If discussed in detail, these statements would require some 

 modification. 



With the second subject the results have not been so definite. There is usually 

 a distinct increase of volume of the brain when he goes to sleep, and in several 

 cases there is a marked fall with awakening. The Traube-Hering wave in the 

 volume and in the breathing is not so prominent, but is still present; and its rela- 

 tions are the same. The breathing wave in the brain curve, on the other hand, 

 often seems to follow the depth of breathing, and to be larger while the subject is 

 awake. The variations may be due in part to the fact that the subject was more 

 nervous, and never slept very soundly nor very long during the experiments. 



The Difference between a Habit and an Idea. By S. H. RowE. 



The Relation of Imitation to the Theory'of Animal Perception. By G. H. Mead. 



Kinaesthetic and Organic Sensations: Their Role in the Reactions of the White 



Rat to the Maze. By John B. Watson. 



The work here reported grew directly out of the experiments carried out some 

 years ago by Small at Clark University. In our experiments a maze very similar 

 to the one used by Small was adopted. The floors and sides of the galleries, how- 

 ever, were made of four inch boards instead of wire netting. Very gentle male rats 

 were used in all crucial experiments. An accurate record was kept of the forma- 

 tion of the maze association, consisting of the variations in time, number of 



