Animal Senses Term Paper

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Animal Senses

Herman, Pack and Hoffman-Kuhnt performed relatively rigorous experiments to determine the source of dolphin recognition of objects; they wanted to discover, among other things, whether "dolphins attained the shape discriminations (of objects) through associative learning or direct perception" (Herman et al. 1998 292). Fukuzawa, Mills and Cooper sought to determine the mechanism by which domestic dogs responded to commands. Greenberg wanted to discover the facts about depth perception in two species of Asian rodents, the Mongolian Gerbil and two varieties of Spiny Mice.


The experiments run by Herman et al. involved a single dolphin, a female named Elele, and were designed to determine whether echolocation or visual cues were central to dolphin recognition of objects that appeared in their environment. The researchers were extremely rigorous in setting up each experiment, avoiding contamination between visual and echolocation fields; the objects used for the dolphin's recognition tests were never available for both visual and echoic inspection at the same time.

When the trials had begun, Elele chose correctly in 49 of the first 50 trials at recognizing the objects introduced. The researchers noted that their results demonstrated an "impressive capability for direct cross-modal shape recognition" (Herman et al. 1998 298).

These were simple trials, however, with the dolphin being allowed to make her identification of the object immediately upon experiencing it. More advanced tests involved delaying her decision; There too, however, Elele excelled, responding correctly 99.2% of the time in the delayed recognition trials.

The experiments were sufficiently sophisticated that the dolphins reaction/response times were also measured. From the dolphin's responses in this mode, the researchers concluded that the dolphin required a bit more time to reach a decision when the objects introduced were less familiar and more complex than the objects in the original tests.

The results of all the experiments, both the simple ones and the ones involving time delays, suggested to the researchers that "dolphins possess a fundamental ability for shape perception through their echolocation sense." (Herman et al. 1998 303). On the other hand, it also became clear that the dolphin employed her visual sense when needed, leading to the conclusion that dolphins view objects holistically.


This experiment sought, above all else, to avoid a Pavlovian response in the dogs. In short, when setting up the experiment, Fukuzawa et al. went to enormous trouble to ensure that their subjects were not influenced in any way by reward, not even so small a reward as the warmth of a human voice. They first trained the dogs in the experiment to two commands -- come and sit -- and thereafter used a sort of disembodied voice to issue those commands in their experiments. The handler wore dark glasses so the dogs could not make eye contact and perform on that basis, and the commands themselves were issued by a voice recorder situated near the handler. The researchers wanted to avoid the "clever Hans" syndrome in which a domesticated animal (although Hans was a horse, and horses are not, in the way dogs are, domesticated animals) performs according to cues received emotionally form the handlers.

In addition, the exact pronunciation of the words was altered, particularly the vowel sounds, so that the researchers could attempt to determine what part of the word it was that the dogs were responding to.

The baseline training for the dogs was relatively lengthy; each one had to be confirmed as knowing the two commands in order to be included in the experiment. The time required for the same handler/trainer to teach the dogs these commands varied.

In the experiments, the dogs did not perform very well, with a very low level of word recognition as measure by the experimental rubric, which included variables from immediate response to delayed response to wrong response to no response at all.

The research took into account the possible ways in which the dogs might, or might not, hear various sounds contained in the words, noting that fricatives are not specific to each speaker and would therefore be heard in the same way by the dogs no matter who spoke the words, while vowel sounds are very individual and might have an impact on the dogs' responses.

The result of the study was that dogs "respond to the whole command word by may also generalize certain acoustically similar phonemes (e.g., one stop sound may not be differentiated from another)" (Fukuzawa et al. 2005 119). Further, the research noted that in practical terms, it would not be wise to assume that a command given by one handler would be received and acted upon by a dog in the same way when the command was given by another handler. Their ultimate finding was that different dogs may respond differently to the same command coming from different handlers.

Gerbils and mice

Greenberg was at pains to note that it was "experimentally naive" female Mongolian gerbils that were used in this experiment; possibly he wanted to clarify that they had had no other experiences regarding mazes or food or any of a number of other behavioral issues a researcher might have wanted to address.

The investigation itself was concerned with finding out if the gerbils and mice used tactile or visual senses in determining actions to take; in this case, climbing down from a platform. The experiment was designed so that the gerbils and/or mice could use either one or both senses in determining whether to climb down; a failure to climb down was assumed if the animal had not, in fact, climbed down after a period of two minutes.

Some of the conclusions seem almost too simple to note, but Greenberg did note them. One of these is that spiny mice, descent time increased as the height of the platform increased. Another finding that seems so simplistic as to be unworthy of mention is that there were subtle differences between the descent times of gerbils and spiny mice, and between the two different kinds of spiny mice as well.

While the experiment was supposedly designed to determine whether or not gerbils and spiny mice used depth perception as an aid to climbing down from high spots, the conclusion arrived at by Greenberg was that the difference he observed might be due to differences in visual information processing between species and not to depth perception differences per se.

In addition, the experiments were designed so that any natural environmental clues would be removed. In fact, virtually any clues were removed in some cases, with a pure white ground used to prevent the animals from gaining clues from texture and so on; in other experiments, a patterned ground, but one unlike those found in the natural habitats of the animals, was used.

Finally, Greenberg concluded that his experiments demonstrated "a difference between gerbils and spiny mice with respect to her utilization of an dependence on sensory information" (1986 83). This seems a very insignificant conclusion considering the time and effort expended.


Of these three experiments, the two that were most like each other were the dolphin and gerbil/spiny mice experiments. In both of these, non-domesticated animals were used as subjects and the experiments themselves allowed for substantial manipulation of the test elements by the researchers, as well as opportunities for gathering quantitative data that could later be analyzed for correspondence to a set of assumptions.

On the other hand, the dog experiment seems very different. First, in involved a domesticated animal with whom humans interact daily. A few humans interact frequently with dolphins; it could reasonably be said that no humans interact frequently -- at least by choice -- with mice and gerbils.

However, in some ways, the dog and dolphin experiments are more similar to each other than either is to the gerbil/mice study. While dolphins are not domesticated animals, for thousands of years, mankind has been fascinated by dolphins and, in the past half century especially, has come to regard them as sort of the 'humans of the sea,' or, in other words, an animal life-form with a high degree of intelligence. At times, discernment is even attributed to them, and other 'human' mental qualities. Likewise, we have certainly anthropomorphized dogs, despite their apparent lesser intelligence than dolphins. We depend on canines to perform certain tasks, in fact, from bringing in the newspaper to guiding blind humans to guarding cattle. Humans have been fascinated by the prospect of having dolphins carry out tasks for us in the sea, as well.

Taking each experiment by itself, however, makes it clear that none of these studies offers as much information as it probably intended to do.

The dolphin experiment, perhaps the most thoughtful of the three, did conclude -- however shakily -- that dolphins are capable of holistic recognition, that it isn't only visual clues or only their ability to perform echolocation that allows them to correctly identify objects introduced to their environment. The research noted that dolphins displayed and ease of recognition of objects. Moreover, they found that prior…

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