The subjects were the first three hundred individuals tested in the experimenter's larger study 2 on mental inheritance. Since the families first tested were selected from the entire experimental group, because of geographic accessibility and other considerations not relevant to the test itself it will be sufficient to indicate how the basic group was chosen. The basic group comprised all children in the Palo Alto and Mayfield public schools born within a given year, the limits of the year being so chosen that a child born in the middle of it would be just thirteen years old at the estimated middle of the testing period; i.e., the children were 12-6 to 13-6 as nearly as could be secured. An effort was made to test all these (basics), all their fathers and mothers, all brothers and sisters (sibs), all other available relatives (remotes) and any other persons sufficiently interested in the experiment to be willing to act as subjects (irregulars). Deductions from the group resulted from removals to inaccessible areas, not probably a selective factor; refusals, possibly a selective factor balancing or tending to balance the superior selection in this region, since the impression remains that more difficulty was experienced, on the average, in securing the cooperation of university professors' families, etc., than with ranchers, laborers, merchants, etc.; and a few cases in which the supposed basic was found to be more than thirteen years old. Many of the irregulars, on the other hand, were university people, some selected particularly for their known high ability. In addition, individuals who did not attempt recall on the substitution test were not included, whatever their performance on the substitution. No selection is presumably to be encountered on the ground of illiteracy in English or of inferior education, since the test appears to be almost completely non-verbal.The females outnumber the males about five to four (167 to 133). This reflects (1) the preponderance of girl students on whom the test 1 Acknowledgment is made to Dr. W. R. Miles for the fundamental suggestion for collecting the recall data.
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