Heffner Rickye S, Heffner Henry E
U Toledo, OH.
J Comp Psychol. 1988 Mar;102(1):66-71. doi: 10.1037/0735-7036.102.1.66.
A comparison of the ability of mammals to localize sound revealed that among the animals examined to date, none of the rodents have been able to localize as accurately as the carnivores. Because all of these rodents are prey animals, the question arises as to whether their poor localization acuity is a phyletic trait of Rodentia or whether it is a trait common to prey species that may be under less selective pressure than predators to localize sound accurately. To answer this question, sound localization acuity was determined in a species that is both predatory and a rodent, the northern grasshopper mouse. Localization thresholds for a single 100-ms noise burst were determined for three grasshopper mice using a conditioned avoidance procedure. Their 50% discrimination threshold of 19 degrees is larger than that of any of the previously tested carnivores and well within the range of other rodents. However, calculations of the binaural sound localization cues available to rodents (based on their head size) suggest that the grasshopper mouse may make more efficient use of the available locus cues than other rodents. Thus, although the grasshopper mouse cannot localize as accurately as carnivores, it appears to be more accurate than predicted for a nonpredatory rodent of its size.
对哺乳动物定位声音能力的比较显示，在迄今为止所研究的动物中，没有一种啮齿动物能够像食肉动物那样精确地定位声音。由于所有这些啮齿动物都是被捕食的动物，于是就出现了这样一个问题：它们较差的定位敏锐度是啮齿目动物的系统发育特征，还是被捕食物种共有的特征，这类物种可能比捕食者面临更小的精确声音定位的选择压力。为了回答这个问题，对一种既是捕食者又是啮齿动物的北蝗鼠进行了声音定位敏锐度的测定。使用条件性回避程序，测定了三只蝗鼠对单个100毫秒噪声脉冲的定位阈值。它们19度的50%辨别阈值比之前测试过的任何食肉动物都要大，并且完全在其他啮齿动物的范围内。然而，根据啮齿动物的头部大小（对其可用的双耳声音定位线索）进行的计算表明，蝗鼠可能比其他啮齿动物更有效地利用可用的定位线索。因此，尽管蝗鼠不能像食肉动物那样精确地定位声音，但对于与其体型相当的非捕食性啮齿动物来说，它的定位似乎比预期的更精确。
