This paper describes an attempt to condition the pupillary response to an auditory stimulus. Conditioning of the pupil is not new. It was reported as early as 1916 by Watson (10). In spite of the many experiments which have been performed since then (1,2,4,6,7,8,9), there is no clear understanding of the necessary and sufficient conditions for the production of this conditioned response. In fact, there is considerable disagreement as to whether the pupil can be conditioned at all (8, 9). In view of the contradictory findings in this field, the recently published experimental results of Baker (1) and Metzner and Baker ( 7) are startling in their implications. Not only do they report conditioning of the pupillary response but also they claim that conditioning was established in two trials provided the auditory stimulus was below the 'conscious limen' (1, p. 13). Baker presents evidence to show that if the auditory stimulus is below this limen, a conditioned response of the 'disturbance' type can be shown to exist at the second simultaneous presentation of light and tone, and the 'final form' response appears at the third trial. This final form response is very stable and very specific. He also states that if the auditory stimulus is supraliminal, a much longer series of paired presentations (from 29 to 105 trials) is necessary to obtain the CR.These results seemed important enough for the theory of conditioning to warrant a repetition of the experiment. The results of this repetition are reported in the following pages. APPARATUS The apparatus (Fig. i) consisted of three parts: the pupillometer, the recording device, and the stimulating instruments. The pupillometer was a modification of similar devices described by Baker (l), and Ferree and Rand (3), and utilized the
Although the perception of mechanical vibration through the skin is a common experience, it has only recently received attention from the experimental psychologist. The lack of scientific interest was probably due to the fact that although the feeling of vibration is of everyday occurrence, it does not seem to play a very important part in the adjustment of the human being to his environment. Not until it was realized that a knowledge of the sensory mechanism involved in vibratory stimulation of the skin would contribute greatly to the understanding of the other cutaneous sensory functions did investigations of this problem become numerous.These investigations have resulted in a considerable number of facts concerning vibratory sensitivity. Determinations have been made of the absolute and differential limens for both frequency and intensity (3, 6) and of other psychophysical functions (2, 7, 8). However many other characteristics of the vibratory sense must be known before its nature can be adequately described, and one of these characteristics is fatiguability. The experiment to be reported in this paper is a study of the effect on the threshold of vibration of prolonged stimulation at various frequencies and intensities.Only two experimenters have attacked this problem directly. Kampik (4) had his subjects clutch a wooden stick which was set into vibration by means of a motor-driven toothed wheel. He found that at the end of an hour the perception of vibration had disappeared and the subject complained that his arm felt numb for some time afterward. In this experiment no attempt was made to relate the amount of fatigue to the characteristics of the stimulus.
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