The choice behavior of primates, including humans, displays a distance effect: Latency to choose between alternatives appears to increase with smaller differences in value. There is, so far, no demonstration of this effect in birds. Tests of distance effects in birds have been conducted in binary choice situations with a dominant alternative, where one alternative is superior to the other in all aspects that meaningfully contribute to value (e.g., provides access to the same reinforcer, but with a shorter delay). The present study considers the possibility that including dominant alternatives in choice tests precludes distance effects. Four pigeons were presented with binary choices between alternatives that varied in amount and delay. Some choices had a dominant alternative (smaller–sooner or larger–later vs. smaller–later) and some did not (smaller–sooner vs. larger–later). Across phases, only the delay to the smaller–sooner reinforcer varied. Distance effects were expected to be expressed as longer latencies as choice between smaller–sooner and larger–later reinforcers approached indifference. Despite the sensitivity of choice to differences in amount and delay, no distance effect was observed. Alternative explanations for the failure to find a distance effect in pigeon choice, including the Sequential Choice Model (SCM), are discussed.

中文翻译：

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未能在鸽子选择中找到距离效应：操纵数量和强化延迟

灵长类动物（包括人类）的选择行为显示出距离效应：在备选方案之间进行选择的延迟似乎随着价值差异的减小而增加。到目前为止，还没有在鸟类中证明这种效应。鸟类的距离效应测试是在二元选择情况下进行的，其中一个选择在所有方面都优于另一个对价值有意义的贡献（例如，提供对相同强化物的访问，但延迟更短） . 本研究考虑了在选择测试中包括主要替代品排除距离效应的可能性。向四只鸽子提供了数量和延迟各不相同的备选方案之间的二元选择。一些选择有一个占主导地位的选择（更小——早或更大——后来 vs. 较小-稍后），有些则没有（较小-较早与较大-稍后）。在不同的阶段，只有对较小的——较早的强化物的延迟有所不同。预计距离效应将表现为更长的延迟，因为在较小的（较早的）和较大的（较晚的）强化物之间的选择接近无差异。尽管选择对数量和延迟的差异很敏感，但没有观察到距离效应。讨论了在鸽子选择中未能找到距离效应的其他解释，包括顺序选择模型 (SCM)。尽管选择对数量和延迟的差异很敏感，但没有观察到距离效应。讨论了在鸽子选择中未能找到距离效应的其他解释，包括顺序选择模型 (SCM)。尽管选择对数量和延迟的差异很敏感，但没有观察到距离效应。讨论了在鸽子选择中未能找到距离效应的其他解释，包括顺序选择模型 (SCM)。