Although the occurrence of incoherent reactions is hardly subject to doubt, yet in no instance is it possible to establish with certainty that a given reaction is of this type, for in no instance can a remote, or an imagined, or a merely symbolic relationship between stimulus and reaction be positively excluded. Some, indeed, would assert that some such relationship must necessarily exist in every instance, at least in the domain of the subconscious. This circumstance necessitates the placing of this type of reactions in the unclassified group. In practice it may be found advisable in some cases to analyze the unclassified reactions with a view to ascertaining to what extent each of the various types is represented among them. But one here treads on slippery ground, and one must be continually warned against the danger of erroneous conclusions. § 5. ORDER OF PREFERENCE. After having developed the classification here proposed we found that there was still considerable room for difference of opinion in the placing of many reactions, owing to the circumstance that in many cases a reaction presents features which render it assignable under any one of two or more headings. To leave the matter of preference in grouping: to be decided in each case according to the best judgment of the experimenter would mean introducing again the play of personal equation, and would thus court failure of all our efforts to accomplish a standardization of the association test. Therefore, the necessity of establishing a proper order of preference for guidance in the application of the classification became to us quite apparent. In the arrangement of the order of preference we were guided mainly by two principles, namely: (i) as between two groups of unequal definition, the one which is more clearly defined and which, therefore, leaves less play for personal equation is to be preferred; (2) as between two groups of equal definition, the one which possesses the greater pathological significance is to be preferred. In accordance with these principles we have adopted the order of preference shown in Table III., placing every reaction under the highest heading on the list under which it may be properly classed. TABLE III 1. Non-specific (common). 2. Doubtful reactions. INDIVIDUAL REACTIONS. 3. Sound reactions (neologisms). 4. Neologisms without sound relation. 5. Repetition of preceding reaction. 6. Reaction repeated five times. 7. Repetition of preceding stimulus. 8. Derivatives. 9. Non-specific reactions. 10. Sound reactions (words). 11. Word complements. 12. Particles of speech. 13. Association to preceding stimulus. 14. Association to preceding reaction (by frequency tables). 15. Repetition of previous reaction. 16. Repetition of previous stimulus. 17. Normal (by appendix). 18. Association to preceding reaction (without frequency tables). 19. Unclassified. § 6. ERRORS INVOLVED IN THE USE OF ARBITRARY OBJECTIVE STANDARDS.