Hoffman H S, Selekman W L, Fleshler M
J Exp Anal Behav. 1966 Nov;9(6):649-53. doi: 10.1901/jeab.1966.9-649.
Pigeons trained to peck a key for food were periodically presented with tones ending with electrical shock until tone presentation consistently suppressed ongoing pecks. Shock was then discontinued and gradients of stimulus generalization were assessed by presenting tones with frequencies above, below, and at the frequencies of those used to develop conditioned suppression. When the training tones had frequencies at 670 and 1500 cps, resulting gradients were bi-modal with peak suppression at 670 and 1500 cps. Of the other test tones, 1000 cps produced the most suppression. When the training tones had frequencies at 450 and 2250 cps, bi-modal gradients were again obtained with peak suppression to the 450 and 2250 cps tones. Of the other test tones, 1000 cps produced the least suppression. These results support the hypothesis that generalized response tendencies summate.
经过训练会为了获取食物而啄击按键的鸽子，会定期听到伴随电击结束的音调，直到音调呈现持续抑制正在进行的啄击行为。然后停止电击，并通过呈现高于、低于以及与用于形成条件性抑制的频率相同的音调来评估刺激泛化梯度。当训练音调的频率为670和1500赫兹时，产生的梯度是双峰的，在670和1500赫兹处抑制峰值最大。在其他测试音调中，1000赫兹产生的抑制作用最强。当训练音调的频率为450和2250赫兹时，再次获得双峰梯度，对450和2250赫兹音调的抑制峰值最大。在其他测试音调中，1000赫兹产生的抑制作用最小。这些结果支持了泛化反应倾向会累加的假设。
