equal probability of eliciting an approach from females in hearing range.
More specifically, for the act of deception to work, females must recognize
the call as a food call, must perceive the call as an indication that a male
has discovered food, and must then approach the male. Results show that
females approached males 86% of the time when they called in the presence of food but only approached 35% of the time when males called in
the absence of food. Further, females were more likely to approach males
who called in the absence of food when their call rates were high than when
they were low, and were more likely to approach when they were close to
the male than when they were far. When females failed to approach in
response to a male calling in the absence of food, males often approached
females. These results suggest that males attempt to use food calls to attract
females and that females assess the veridicality of the signal by using the
rate of calling as well as contextual information. It may be that the lower
rate of approach to deceptive calls is due to perceptible differences in the
acoustic morphology of the calls, but no acoustical analyses of honest versus
deceptive calls has yet been performed.
The chicken food-call system satisfies our definitional conditions. Once
again, however, it appears to violate the prediction of rarity. Specifically, the
food call is primarily given in the context of food and, as recent production
and perception experiments suggest, it functionally refers to food rather
than to a more generic event or context such as the willingness to engage
in social interactions (Evans and Marler 1994; Evans and Evans 1999).
When chickens produce food calls, they elicit characteristic responses that
are distinct from the responses elicited by contact or alarm calls. Chickens
apparently take advantage of the referential properties of the food call as
well as the behavior it elicits in females to produce such calls in the absence
of food. For reasons that are currently unclear, males appear to get away
with such lies at relatively high rates. Almost 50% of all food calls are given
in the absence of food and, when given, elicit female approach approximately 33% of the time.
In terms of a mismatch between signal and context, the chicken study
provides an example of a lie of commission. What is unclear, especially
when contrasted with the previous examples of avian deception, are the
costs and benefits of this putative case of deception. Thus, males presumably gain some benefit by eliciting an approach from a female. However,
Marler and his colleagues have yet to demonstrate that the female’s
approach translates into a reproductive advantage for the male. In terms of
costs, females lose by disrupting their current activity and by traveling a distance to the male. At present, it is unclear whether there are costs that
would constrain or limit the frequency with which males give false food
calls. For example, is it the case that females are less likely to mate with a
male who has given a food call when no food is available? One could test
this possibility with a design that we have already mentioned. Specifically,
make one male completely dishonest (100% of his calls are produced in the
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W.T. Fitch and M.D. Hauser
More specifically, for the act of deception to work, females must recognize
the call as a food call, must perceive the call as an indication that a male
has discovered food, and must then approach the male. Results show that
females approached males 86% of the time when they called in the presence of food but only approached 35% of the time when males called in
the absence of food. Further, females were more likely to approach males
who called in the absence of food when their call rates were high than when
they were low, and were more likely to approach when they were close to
the male than when they were far. When females failed to approach in
response to a male calling in the absence of food, males often approached
females. These results suggest that males attempt to use food calls to attract
females and that females assess the veridicality of the signal by using the
rate of calling as well as contextual information. It may be that the lower
rate of approach to deceptive calls is due to perceptible differences in the
acoustic morphology of the calls, but no acoustical analyses of honest versus
deceptive calls has yet been performed.
The chicken food-call system satisfies our definitional conditions. Once
again, however, it appears to violate the prediction of rarity. Specifically, the
food call is primarily given in the context of food and, as recent production
and perception experiments suggest, it functionally refers to food rather
than to a more generic event or context such as the willingness to engage
in social interactions (Evans and Marler 1994; Evans and Evans 1999).
When chickens produce food calls, they elicit characteristic responses that
are distinct from the responses elicited by contact or alarm calls. Chickens
apparently take advantage of the referential properties of the food call as
well as the behavior it elicits in females to produce such calls in the absence
of food. For reasons that are currently unclear, males appear to get away
with such lies at relatively high rates. Almost 50% of all food calls are given
in the absence of food and, when given, elicit female approach approximately 33% of the time.
In terms of a mismatch between signal and context, the chicken study
provides an example of a lie of commission. What is unclear, especially
when contrasted with the previous examples of avian deception, are the
costs and benefits of this putative case of deception. Thus, males presumably gain some benefit by eliciting an approach from a female. However,
Marler and his colleagues have yet to demonstrate that the female’s
approach translates into a reproductive advantage for the male. In terms of
costs, females lose by disrupting their current activity and by traveling a distance to the male. At present, it is unclear whether there are costs that
would constrain or limit the frequency with which males give false food
calls. For example, is it the case that females are less likely to mate with a
male who has given a food call when no food is available? One could test
this possibility with a design that we have already mentioned. Specifically,
make one male completely dishonest (100% of his calls are produced in the
114
W.T. Fitch and M.D. Hauser