When I was asked to either open a discussion or read a paper, I felt a great difficulty in choosing a subject, and I think my choice has been influenced considerably by the interest shown by the public in mental defect. Probably all of us are conversant with some of the various methods that are in use for testing the intelligence. These appear to resolve themselves into either valuing or “marking” by plus or minus or using numbers. It has always appeared to me that in marking by plus or minus signs it is very difficult to form an opinion as to whether it should be + ! or + ?, whereas it is easier to use figures. For instance, you say to a child, “What is the difference between an orange and a banana?” and you desire two comparisons to be given. If you give one mark for a definite comparison and no marks for an indefinite comparison it appears fairly simple, whereas if you are marking by the plus signs and one comparison is correct and the other wrong, it appears to me to be difficult to tell which of the plus signs one should use in marking the whole result. I therefore use the point scale test of Yerkes and Bridges. This method, with some slight modifications of my own, I and my colleagues have used in all the cases. I do not believe that a child cannot be tested until it has reached the age of five years. In this I have some support from recent American workers, and a method of testing the young child may yet be devised. Therefore in marking I do not, as Yerkes and Bridges do, start from five years of age, but as though the child could think from birth. The two tests which I hope to discuss at this meeting are those of association and suggestion. These two units appear to offer some interesting theories which might be worthy of further investigation. In a sense these two tests are dependent on each other psychologically and throw some light on the elucidation of some of our problems, and may perhaps enable us to form deductions of some diagnostic and prognostic value.