PSYCHOLOGICAL PROGRAM AND TECHNIQUE. 159 



distance from the base-line of 1 to the lowest point of 2. The mechani- 

 cal magnification in the record was 6 times the actual height of muscle- 

 thickening.^ There is naturally some confusion in the tracings of such 

 records, but it is evident that when the interval between stimuli is 

 decreased to a certain point, the second stimulus fails to produce a 

 reflex. When the interval is lengthened slightly, a small reflex appears 

 in response to the second stimulus. A record was kept of the height 

 to which the bar which rests against the subject's knee had to be raised, 

 and also whether the subject had on shoes or slippers. 



(9) Reaction Time for Turning the Eye to a New Point of Regard. 



This measurement was always made in the morning. The turning of 

 the eye to a new point of regard in response to the sudden appearance 

 or movement of some object which is removed from the line of clearest 

 vision is an important reaction for the organism. It would seem that, 

 considering the multitude of reactions of this character which an indi- 

 vidual makes in the course of his everyday life, an adult subject in 

 coming to the Laboratory would be perfectly practiced in this regard. 

 In any wide range of neuro-muscular measurements, particularly when 

 new and unpracticed subjects are to be used, this measurement of 

 eye reactions is an especially promising one for consideration and use. 

 Suitable apparatus for photographically recording the eye reactions has 

 been designed and used by Dodge and has been fully described by him.^ 

 Briefly, the record is made by photographing a beam of light reflected 

 from the cornea of the subject's eye. This calls for a source of illumi- 

 nation, an adjustable head-rest, mirrors, a lens, a camera of suitable 

 design to move the photographic plate, and some device for presenting 

 stimuli to the eye. 



Several modifications and additions have been made to the apparatus 

 as used by Dodge and Benedict in the alcohol investigation. Certain 

 definite aims were in mind in making these changes : (1) a form of stimu- 

 lus device was desirable, which would provide more variety of stimulus 

 positions and still give no secondary criteria to the subject; (2) the field 

 of view of the subject should include only what was necessary for him to 

 see; (3) it should be possible to place a new subject in position quickly 

 and to inform him definitely of his task ; the subject who is familiar with 

 the test should be able to place himself in position, adjusting the head- 

 rest as directed by the operator; (4) for laboratory economy, as well as 

 to avoid the possibility of giving secondary criteria to the subject, the 

 apparatus should be operated by one person, and from one position; 

 (5) more reactions should be taken to get a better s ample of the sub- 



^ The records for some readers might be more easily understood in connection with the actual 



movements of the muscle if the figure is turned upside down; a rise in the curve will then 



be seen to correspond to a rise or a thickening of the muscle. 

 2 Dodge, An experimenta study of visual fixation, Monograph Supplement of the Psychological 



Review, No. 35, 1907. See also Dodge and Benedict, Carnegie Inst. Wash. Pub. No. 



232. 1915, p. 79. 



