Object Perception and Representation by Echolocating Dolphins

通过回声定位海豚对物体的感知和表征首席研究员：路易斯·m·赫尔曼博士本实验室继续调查宽吻海豚（Tursiops truncatus）通过回声定位感知物体形状的能力。海豚如何通过回声定位来表示它所观察到的物体？它是只感知到从物体发出的原始回声，还是像视觉一样，直接感知到物体的形状？先前发表的研究使用了跨模态匹配-样本程序来证明海豚可以通过回声定位和视觉来自发地识别物体。结果表明，通过回声定位感官可以直接感知到物体的形状，并且回声定位所获得的物体表征与视觉所获得的物体表征是协调或紧密结合的。这些结论有力地修正了之前关于海豚回声定位的观点，即海豚对不同物体的辨别是基于学习将返回回声的原始声音线索（例如，振幅、高光结构或光谱组成）与看到的事物或收到的奖励联系起来。持续的研究现在询问海豚的表征如何忠实地保存被回声的物体的空间结构，以及什么机制可以通过回声定位支持形状感知的构建。其他问题包括海豚通过回声定位的形状感知是否随着物体的方向、物体的材料组成以及物体大小的变化而不变。在每次操作中，物体的形状将保持不变，但物体的声音反射特性将发生变化。跨模态匹配技术将继续使用，以及模态内技术，其中在回声定位和视觉而不是跨感官中检查对象识别性能。在这些研究中考虑的问题和获得的发现建立了与婴儿和成人以及非人类的基于物体的感知和感觉间感知的问题和发现的联系。这些研究还涉及人类和非人类动物的记忆和表征的一般问题。

Object Perception and Representation by Echolocating DolphinsPrincipal Investigator: Louis M. Herman Ph.D.This research continues the investigation by this laboratory of the ability of the bottlenosed dolphin (Tursiops truncatus) to perceive the shape of objects through its echolocation sense. How does the dolphin represent objects it inspects through echolocation? Does it perceive only the raw echoes returning from ensonified objects or, like vision, does it directly perceive the shape of the object? The prior-published studies used a cross-modal matching-to-sample procedure to demonstrate that a dolphin could spontaneously recognize objects across the senses of echolocation and vision. The results suggested that object shape is directly perceived though the echolocation sense, and that the representations of objects obtained through echolocation are coordinated with or closely integrated with the representations obtained through vision. These conclusions strongly revise previous views of dolphin echolocation that postulated that discriminations among different objects were based on learning to associate the raw acoustic cues of returning echoes (e.g., amplitude, highlight structure, or spectral composition) with things seen or with reward received. The continuing investigations now ask how faithfully the dolphin's representations preserve the spatial structure of the object being ensonified, and what mechanisms can support the construction of a shape percept through echolocation. Other questions include whether the dolphin's perception of shape though echolocation is invariant with changes in the orientation of the object, with changes in material composition of the object, and with changes in object size. In each manipulation, object shape will remain constant, but the sound reflection properties of the object will vary. The cross-modal matching technique will continue to be used, as well as intra-modal techniques in which object recognition performance is examined within the senses of echolocation and vision rather than across the senses. The issues considered in these studies and the findings obtained establish links with issues and findings in object-based perception and in intersensory perception in infant and adult humans, and in nonhumans. The studies also make contact with general issues in memory and representation in human and nonhuman animals.