The problem of cooperation during mental tests is especially important in the early ages. Screaming, struggling, kicking, clinging to the mother, are manifestations frequent in the first four years though rarely observed in testing children of school age. Such behavior often invalidates tests that may be well chosen from a psychometric viewpoint. Psychologists at the Institute for Juvenile Research are all agreed that the 'imitation' test in the Kuhlman two year level, for example, is the least 'acceptable'; i.e., children are more resistant during this test than during any other in his series. This holds true whether the testing is done under the adverse conditions of a 'Better Baby Conference' held in the County Fair or under the natural conditions of the nursery. Moreover eight psychologists (four men, four women), experienced in testing at the numerous baby conferences held in Chicago and throughout the State of Illinois in the past four years, are agreed that regardless of the test used, more difficulty in giving the tests is encountered with the threeyear-olds than with any other age group.This behavior presents an important problem because it interferes with testing. But this practical consideration involves the study of this resistance as a problem of human behavior, since it must be determined whether the resistance is inherent in the tests chosen, in the technic of their administration, in the surroundings, or in the group that is tested. The psychologist interested in formulating new tests for infants and children must consider this factor when devising tests. The student of behavior is interested primarily in knowing whether this behavior is incidental to the testing 6 «3 I 35-3 59 i 47-3 37-5

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