Literary Notices. 33 1 



The sensory stimulations from which Hans took his cue consisted of certain 

 slight movements of his questioner's body. After Herr von Osten had stated the 

 problem, he tended always to bend the head and trunk slightly fonuard; where- 

 upon Hans extended his right foot and began to tap without putting his foot back 

 after each successive tap. When the desired number of taps was reached, Herr von 

 Osten would give a slight upward jerk of the head. At this second signal, the horse 

 would retract the foot to its normal position (this last movement was never counted). 

 Now when the horse had ceased to tap, the questioner would raise the head and 

 trunk to an upright position. This second and more extensive movement (that is, 

 more extensive than the slight upward jerk of the head) cannot be regarded as the 

 signal for the retraction of the foot. If the larger movement, however, did not 

 follow the slight upward jerk of the head, the horse would give a single vigorous 

 tap with the left foot, without however first extending it. Horizontal movements 

 were without effect in eliciting responses from Hans. All downward motions of 

 the body, eyebrows, nostrils, arms, etc., were signs to begin the tapping movement, 

 whereas the raising of these parts was a signal to cease tapping. 



The results of the experiments conducted in the laboratory uport human sub- 

 jects in the role of Hans form an interesting contribution to the study of the psy- 

 chology of involuntary movements. 



Surely, this careful and painstaking work of Pfungst may be prescribed as an 

 antidote henceforth and forever to those untrained but enthusiastic observers who 

 may be filled with the desire to describe the doings of pet animals in glowrng anthro- 

 pomorphic terms. j. b. w. 



Yale Psychological Studies. Edited by Charles H. Judd, n. s. vol. i, no. 2. Psychological 

 Review Monograph Supplements, vol. 8, no. 3, pp. 227-423. 1907. 



The second half of the first volume of the new Yale Studies contains five papers, 

 at least four of which show that perfection of experimental technique which is char- 

 acteristic of Professor Judd's laboratory. In Tonal Reactions, Dr. E. H. Came- 

 ron gives an interesting study of tones as produced by the human voice, both with 

 and without distractions. "The attempt to sing a uniformly sustained tone is 

 not successful. The beginning of the tone is markedly irregular and there is a 

 tendency to raise the pitch towards the end of the tone. There is usually a har- 

 monious relation between the sung tone and the distracting tone." Mr. F. N. 

 Freeman contributes some Preliminary Experiments on Writing Reactions which 

 connect interestingly with the Analysis of Reaction Movements contained in the 

 first half of the volume. Both of these papers have important bearings on the 

 mechanism of consciousness, of which the full significance, in the reviewer's opinion, 

 will appear only later. Mr. H. N. LooMis reports on Reactions to Equal Weights 

 of Unequal Size. He finds that the weight of smaller size is usually raised later 

 than the larger weight, and that the hand which lifts this latter has a much greater 

 muscular tension. With practice the illusion tends to disappear, and so too these 

 differences in the manner of lifting. In Studies in Perceptual Development Profes- 

 sors Judd and D. J. Cowling describe experiments in which subjects learned to 

 draw complex figures. Each figure was shown repeatedly for ten seconds, and 

 after each view the subject reproduced once as well as he could what he had seen. 

 The issue concludes with some remarkable Photographic Records of Convergence 

 and Divergence, including a theoretical discussion of the mechanism of perceptual 



