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The Development and Standardization of a Group Test for Critical Flicker Frequency

出版	U.S. Naval School of Aviation Medicine, 1956
URL	http://books.google.com.hk/books?id=D-wWHQAACAAJ&hl=&source=gbs_api

註釋An adequate group test for critical flicker frequency would increase greatly the speed of data collection for this measure. The present paper describes the development and standardization of such a test. With this group CFF test, ten subjects at a time can be tested in a total of eight minutes. A method of ''constant descent'' is used for stimulus presentation. Production of the stimulus is accomplished by passing the sine wave output of an audio oscillator through a wave-shaping circuit, with the resulting intermittent signal being presented at individual neon lamps. Subjects' threshold judgments are recorded on an operations recorder. The test was administered to 100 naval aviation cadets and 174 naval enlisted men. Subjects were tested in groups of ten and given five trials each. There was no consistent trend in group response level during the five trials, with a maximum variation of 0.5 flasshes/sec from the lowest to the highest mean threshold per trial. Intra-individual variability in response over the five trials tended to be relatively small. There was a decrease in intra-trial variability from the first to the second trial, and no change in variability over the remainder of the trials, indicating that stability of response is reached after the first trial. The test was shown to discriminate significantly between two different populations, the naval aviation cadets and naval enlisted men. (Author).