The reënforcement-inhibition curve plotted on the basis of the 1200 reactions in this series is presented in Fig. 8. Before stopping to consider the important features of this curve we should note the results of certain more accurate experiments with prolonged auditory stimulation.
FIG. 8. Reënforcement-Inhibition curve for prolonged auditory stimulation, based upon amount of reaction. Frog No. 1.
With two animals, No. 2, a female, and No. 3, a male, fifty pairs of reactions were taken for nine different intervals (see Table 5) of auditory stimulation. Each of the curves of Figures 9 and 10 is therefore based upon 900 reactions. The conditions for these experiments were the same as those for the momentary stimulation series, save that the electric bell took the place of the electrically actuated hammer, as the mechanism for auditory stimulation.
FIG. 9. Reënforcement-Inhibition curves for prolonged auditory stimulation, based upon amount of reaction. Female No. 2 —— Male No. 3 ....
The important facts exhibited by the results of these prolonged auditory stimulation experiments in contrast with those with momentary auditory stimulation are: (1) That whereas for the momentary auditory stimulus of a hammer blow the reënforcement is greatest for simultaneous stimuli, in case of the prolonged stimulation with the electric bell, reënforcement increases during an interval of .25˝ of auditory stimulation. Hence, the two conditions of stimulation give us different types of reënforcement-inhibition curve. For the momentary stimulus the maximum reënforcement appears at simultaneity, and for the prolonged stimulus at .25˝; (2) that the transition from reënforcement to inhibition occurs at 1.2˝ in the prolonged stimulation curves, while in the momentary stimulation curves it occurs at .35˝; (3) that the maximum inhibition which appears in the curves under discussion at about 1.5˝ is less in comparison with the amount of reënforcement than that of the momentary stimulation curves; (4) that the auditory stimulus becomes ineffective when the interval during which it continues before tactual stimulation is 2.0˝. The curves of Figures 8, 9, and 10 are then representations of a neural process which passes through a positive and a negative phase in about 2˝. The effect of prolongation of the auditory stimulation interval is to lengthen the period of reënforcement; the period of inhibition shows little modification.
For the purpose of showing in greater detail the nature of the results of this work the data from which the curves of Figures 9 and 10 were constructed are presented in the accompanying Table 5.
FIG. 10. Reënforcement-Inhibition curves for prolonged auditory stimulation, based upon number of reactions. Female No. 2 —— Male No. 3 ....