Comprehension of signs by dolphins (Tursiops truncatus).

Abstract

The authors assessed the ability of 6 captive dolphins (Tursiops truncatus) to comprehend without explicit training 3 human communicative signs (pointing, directed gaze, and replica). Pointing consisted of indicating the target item with the index finger and a fully extended arm. Directed gaze consisted of orienting the head and eyes toward the target item while the rest of the body remained stationary. The replica signal consisted of holding up an exact duplicate of the target item. On the initial series of 12 trials for each condition, 3 dolphins performed above chance on pointing, 2 on gaze, and none for replica. With additional trials, above chance performance increased to 4 dolphins for pointing, 6 for gazing, and 2 for replica. The replica sign seemed to be the most taxing for them (only 2 dolphins achieved results significantly above chance). Taken together, these results indicate that dolphins are able to interpret untrained communicative signs successfully.

Sea lions’ (Zalophus californianus) use of human pointing gestures as referential cues

“…However, this hypothesis has been countered by other findings: human-socialized undomesticated individuals, such as wolves (Canis lupus; Udell, Dorey, & Wynne, 2008;Udell, Spencer, Dorey, & Wynne, 2012), African elephants (Loxodonta africana; Smet & Byrne, 2013), dolphins (Tursiops truncatus; Pack & Herman, 2004, 2007Tschudin, Call, Dunbar, Harris, & van der Elst, 2001), fur seals (Arctocephalus pusillus, Schuemann & Call, 2004) and a gray seal (Halichoerus grypus, Shapiro, Janik, & Slater, 2003) have also been shown to be very successful, some not far from a dog's level of performance. Great apes are generally unskillful (e.g., see Povinelli, Reaux, Bierschwale, Allain, & Simon, 1997), but recently Lyn, Russel, and Hopkins (2010) showed that chimpanzees and bonobos raised in socio-linguistically rich environments perform much better than chimpanzees raised in standard laboratory housing.…”

All Great Ape Species Follow Gaze to Distant Locations and Around Barriers.

“…Also, dolphins (Tursiops truncatus; Tschudin, Call, Dunbar, Harris, & van der Elst, 2001) and South African fur seals (Arctocephalus pusillus; Scheumann & Call, 2004) follow gaze in object-choice situations. Although there was no evidence that dogs (Canis familiaris) follow human gaze outside of a simulated foraging context into free space , they are very skillful in using human gaze in object-choice situations .…”

Ravens,Corvus corax, follow gaze direction of humans around obstacles

“…head and eye direction (Byrne & Whiten 1988;Tomasello & Call 1997)). The ability to follow gaze direction has recently been shown for a number of primates (see review in Emery 2000) and other social mammals such as dogs, Canis familiaris (Miklósi et al 1998), dolphins, Tursiops truncates (Tschudin et al 2001), and goats, Capra hircus (Kaminski et al 2001). Studies follow different paradigms that require individuals either: (i) to visually co-orient with a conspecific and/or human experimenter for tracking locations above, behind or to the side of them (e.g.…”