Purpose: This study aims to clear up some relationships among motivational instructions under 3 situations (reassurance, failure, repeated failure), respiration and electrical skin conductance on memory of verbal materials. Method: These memory materials are 14 syllables passages of 0 and 3 order of approximation to Japanese, and each 15 are arranged alternately. All Materials are presented 2 syllables per second by tape recorder and the recall is required after 30 seconds. The experiment has 3 sessions o f 10 passages and 3 minutes rest is inserted between them. In the 1 st session a standard instruction is given to all the groups, and in the 2nd session one group is given reassurance instruction and another 2 groups are given failure instruction. In the 3rd session one of the latter 2 groups, give n failure iestruction in the 2nd session, is agai n given failure instruction, and another 2 groups a re given neutral instruction. During the experiment respiration and electrical skin conductance of the Ss are measured. Results: (1) In the 2nd session differences of recall scores among the 3 groups was not found, but in the 3rd session the repeated failure group is inferior to another, (2) By the material of 0 order of approximation to Japanese the recall scores of the repeated failure group is inferior to another in the 3rd session, but by the 3rd order of approximation to Japanese there is no significant difference among the 3 groups. (3) About percent changes of resistance (GSR) the reassurance group is Tower than the failure group in the 2nd session. In the 3rd session the group, given neutral instruction after failure instruction, is lower than another 2 groups. (4) In the case of 0 order of approximation to Japanese percent changes of resistance (GSR) is restrained to go down in repeated failure group, but in the case of the 3rd order of approximation to Japanese there is no significant difference among the 3 groups. (5) Absolute level of conductance goes higher in the 1st sossion than before experiment, but after the 1st session it goes neither higher nor lower. (6) Respiration is increased in the experimental situation comparing with before experiment. But there is no significant difference among the various motivational instructions.
In research on teaching, the double blind method is impossible to use (1)(2)(8), but there are several methods to reduce bias. The conclusions from the experiments using those methods will be reliable, provided that there exist other independent data which are consistent with them. There are three levels of experimental research of teaching; the research patterned after experimental psycology, the research of teaching under experimental control and the field research of teaching. A conclsion of an experiment in any branch may be regarded as an independent datum in other branches. In the research of teaching under experimental control, the method which is usually satisfactory for reducing the bias may be the combination of “use of two teaching materials and two groups of subjects with different previous experience” and a “ating scale method with more than three independent observers rating the elements of teaching” being accompanied, if possible, by the “cross-core method in which teacher A who has been using method X and teacher B who as been using method Y are asked to use both method X and method Y”. In the field research of teaching, the methods of reducing bias are “comparison between the lessons given by the excellent teachers from each sect of teaching schools,” “comparison between the prominent lessons and avarage lessons in the same sect of teaching schools”, and other analogous method accompanied with “rating-scale method” In the field research of teaching, all or part of the abilities measured in the evaluation should be as equivalent as possible to all the principal objects of the teaching methods which are the concerns of the study. The methods in the studies other than the typical studies which belong to the branches concerns of three above mentioned and the two way of the treatment of the omission in the investigation are discussed.