SUGGESTIONS FOR LABORATORY WORK 601 



Thought Time Compared with Speech Time. With the apparatus 

 arranged as before let the subject, when stimulated, think the 

 first ten letters of the alphabet before pressing his key. Repeat 

 the experiment; this time having the subject say the ten letters 

 aloud. Make a number of trials and determine the average results. 



THE SPECIAL SENSES 



In the following experiments one member of a pair is to act as 

 subject, the other as experimenter. Members of the pair should 

 alternate in these functions. 



TOUCH 



Localizing delicacy. Let the subject sit with his hand on the 

 table, and with eyes closed. Apply carefully to the back of the 

 hand the points of small dividers separated about % mm. The 

 subject reports whether he feels one point or two points, or is in 

 doubt. Record the result. Change the distance between the 

 points gradually, in successive tests applied to the same region, 

 until the subject reports a change in sensation. The minimal dis- 

 tance at which the two points can be felt as two points is the 

 threshold. 



Record the results of testing for the threshold on the finger-tips, 

 palm, flexor and extensor surfaces of the forearm, cheek, and lips. 



TEMPERATURE 



Cold and Warmth Spots. Outline an area on the back of the 

 wrist about 2 cm. square. Let a blunt pointed metal rod stand in 

 cold water until it has become cooled. Dry it and examine point 

 by point the selected area. Mark the spots at which the cool rod 

 causes sensations of cold. 



Let the rod stand in hot water until it can be felt as hot when 

 dried and touched to the skin lightly, but not so hot as to cause 

 burning or pain. Explore point by point with very light contact 

 an equal area contiguous to that examined for cold spots. Mark 

 with ink the spots at which the rod causes sensations of 

 warmth. 



