Effect of the number of jittering echoes on jittered delay accuracy in a bottlenose dolphina).

Echolocating dolphins are able to resolve echo delay differences on the order of a microsecond or less if tested using jittered, phantom echoes. Rapid comparisons of alternating echo delays likely facilitate this "hyperacuity" compared to paradigms where echo delays change on longer time scales or with fewer opportunities to compare echoes. This study examined how an echolocating bottlenose dolphin's jitter-detection threshold varied as a function of the number of jittered echoes made available for comparison. The dolphin's task was to report when a phantom echo at a simulated range of 10 m began to jitter in delay. Experimental conditions included a single "step" change in echo delay, between 3 and 33 jittering echoes, and an unlimited number of jittering echoes. As the number of jittering echoes increased from 1 to 9, jitter-detection thresholds linearly decreased from 84 to 1.8 μs. There were no significant changes in thresholds for more than nine jittering echoes. The results were consistent with a decision model based on multiple looks and highlight the role of multi-echo processing in dolphin biosonar tasks.