On the other hand, I not seldom found wage-earners, both men and women, who seemed to have really interesting and varied activities and who nevertheless complained bitterly over the monotonous, tiresome factory labor.  I became more and more convinced that the feeling of monotony depends much less upon the particular kind of work than upon the special disposition of the individual.  It cannot be denied that the same contrast exists in the higher classes of work.  We find school-teachers who constantly complain that it is intolerably monotonous to go on teaching immature children the rudiments of knowledge, while other teachers with exactly the same task before them are daily inspired anew by the manifoldness of life in the classroom.  We find physicians who complain that one case in their practice is like another, and judges who despair because they always have to deal with the same petty cases, while other judges and physicians feel clearly that every case offers something new and that the repetition as such is neither conspicuous nor disagreeable.  We find actors who feel it a torture to play the same role every evening for several weeks, and there are actors who, as one of the most famous actresses assured me after the four hundredth performance of her star role, repeat their parts many hundred times with undiminished interest, because they feel that they are always speaking to new audiences.  It seems not impossible that this individual difference might be connected with deeper-lying psychophysical conditions.  I approached the question, to be sure, with a preconceived theory.  I fancied that certain persons had a finer, subtler sense for differences than others and that they would recognize a manifoldness of variations where the others would see only uniformity.  In that I silently presupposed that the perception of the uniformity must be something disturbing and disagreeable and the recognition of variations something which stimulates the mind pleasantly.  But when I came to examine the question experimentally, I became convinced that such a hypothesis is erroneous, and if I interpret the results correctly, I should say that practically the opposite relation exists.  Those who recognize the uniformities readily are not the ones who are disturbed by them.

I proceeded in the following way.  To make use of a large number of subjects accustomed to intelligent self-observation, I made the first series of experiments with the regular students in my psychology lecture course in Harvard University.  Last winter I had more than four hundred men students in psychology who all took part in that introductory series.  The task which I put before them in a number of variations was this:  I used lists of words of which half, or one more or less than half, belonged to one single conceptional group.  There were names of flowers, or cities, or poets, or parts of the body, or wild animals, and so on.  The remaining words of the list, on the other hand, were without inner connection