light, with observer facing subject. Shade one eye with the hand for a minute, 

 then quickly remove it while observing any changes in the iris. To what extent 

 can iris movements be controlled by the subject? 



To observe the automatic focusing, or fixation, response, have subject and 

 observer face each other. Subject holds a pencil vertically at arm's length and 

 fixes his eyes upon it while slowly bringing it toward his face until it is too close 

 to be comfortable. How do the subject's eyes behave? What is there to show 

 whether this is a native or a learned reaction? 



3 To find whether the brain takes part in the reflexes of an animal, use a 

 pithed frog and repeat the stimulations in No. 1 above. ^ 



4 To observe chains of reflexes, or "habits", watch individuals performing 

 familiar and repeated acts to see how closely the succession of movements is 

 duplicated at different times. 



Observe such sequences as using table utensils, cutting food, handling napkin, 

 and so on; dressing and undressing — the order and manner in which the various 

 garments are taken off and put on, and how they are laid down; and smoking — 

 the sequence of acts that a habitual smoker follows. 



Have several classmates remove their coats and lay them on their seats; then 

 have each put his coat on again. Repeat this operation two or three times, and 

 note, first, the different ways in which individuals may be doing what is "the 

 same thing", and then the consistency with which each one follows his own 

 pattern. 



5 To determine reaction time, we may use a series of repeated acts, since it 

 is difficult to measure the fraction of a second involved in most reactions. With 

 one individual keeping time, have the other members of the group form a circle, 

 each member facing the back of the person in front of him; the stimulus is a 

 slap on the back, and the response is a slapping of the back of the person next in 

 front. All will be alert to transmit the stimulus as quickly as possible, but will 

 not anticipate by watching. Repeat the series several times; average the time 

 around and average the time per individual. 



6 To see whether vision is involved in ordinary body equilibrium, compare 

 ability to stand still on one leg, without swaying, with eyes open and then with 

 eyes closed. 



7 To find variations in the skin's sensitiveness to touch, explore different 

 parts of the skin for discrimination between two points touched. Work in pairs, 

 using a two-point contact needle. Explore the back of the hand, the palm of the 

 hand, the tip of the index finger, the forearm, the back of the neck; the experi- 

 menter touches the skin either with one point or with both points at exactly the 

 same time. (Do not press too hard, as a sensation of pain is different from that 

 of touch.) The subject, not seeing the contact, reports whether he feels one point 

 or two. Test each region a sufficient number of times to determine the smallest 

 distance between points which the subject can detect. Use spreads of 20 mm, 

 10 mm, 5 mm, 3 mm, and 1 mm. 



What are the smallest intervals that could be distinguished in each area? 



^See footnote 4, p. 183. 

 299 



