Auditory signals undoubtedly play an important role in animal communication. Presumably as an adaptation for noisy environments, the human brain has developed a tendency to "restore" parts of speech or other noise that may have been blocked by a different noise, creating the illusion that no interruption occurred. This is known as "auditory induction" and "perceptual restoration." This phenomenon has also been observed in animals such as cats, tamarins, macaques, and starlings. One study published in Animal Behaviour examined auditory induction in Hyla chrysoscelis, Cope's grey treefrog.
The study used females to investigate whether these frogs show a similar ability to fill in gaps in various calls in order to facilitate communication. It was found that signals with these gaps were less attractive to females than gap-less signals. This is important because auditory signals play a large role in frog mate choice and mating rituals. However, the results of the study indicated that the "continuity illusion" was not present in these frogs -- in other words, the females did not "hear" sounds that were not there.The researchers did note that their experiment was very limited, because not only did they only study one species of frog, but also their work was not comprehensive. It is possible that a similar type of illusion is caused by other factors not yet investigated.
The authors also noted that how frogs learn and use calls is very different from songbirds and primates. For example, frogs do not appear to learn or recognize any of their calls, and demonstrate less sophisticated social behavior. This makes frogs valuable study subjects, as well as dangerous ones, because they have these differences. Further research into frog vocalizations, as well as into the phenomenon of auditory induction, could be very useful in studies on animal behavior and communication.
Posted by Dana Mirsky (2)
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This is interesting. maybe the females prefer the calls with breaks because they are responding in some way that has not been detected. there are some species of frogs where the females are mute but they use body vibrations to communicate. is it possible that the breaks in the calls are so that the females can respond?
ReplyDeletePosted by Amber Kapchinske
Wow, that’s interesting that frogs are not able to utilize calls as efficiently as songbirds and primates. Do you think this is due to their earlier evolution? I also wonder if their brain anatomy reflects their inability to learn or recognize any of their calls.
ReplyDeletePosted by Katie Kalutkiewicz
How exactly was this tested? A little background on the methods of the experiment might be helpful in explaining the results and what they mean. Why did the researchers use only females? If males were used instead, do you expect different results or do you think the anatomy and perception of males would be the same as the females that were tested?
ReplyDeletePosted by Muriel Herd
I've noticed many frogs seem to tend toward synchronizing their calls. Do you think this could be influenced by the inability of females to practice this vocal induction? If all the calls are synchronized, then there will be less gaps due to background noise. Additionally, if a frog did not synchronize, he would be selected against because the group-song would cause these gaps in his, and the females would not respond to it.
ReplyDelete-Alice Trei
I'm very surprised to hear that frogs do not learn or recognize their species calls. I guess learning is not necessary if you have an innate ability to call, but recognizing other males of your species seems advantageous, because it may affect the dispersal of males who are competing for the same females. Also, I'm curious about how this experiment was performed. Were the females exposed to the gap and gap-less calls in a controlled environment that eliminated background noise? As you described it, maybe auditory induction can only occur when background noise is present.
ReplyDelete-Jane de Verges
The breaks in the calls were meant to mimic what happens in nature when background noise interferes with reception of the entire call - like when you can't hear everything your friend is saying in a crowded, noisy room. The researchers wanted to know if the females would respond differently if they could only receive part of the call.
ReplyDeleteI believe the researchers used females because primarily the female frogs are responding to the calls of the male frogs, and it is this male/female interaction that may be the most important.
Posted by Dana Mirsky