First published online October 27, 2003
Introductory tail-flick of the Jacky dragon visual display: signal efficacy depends upon duration
Richard A. Peters* and
Christopher S. Evans
Animal Behaviour Laboratory and Department of Psychology, Macquarie
University, Sydney, NSW 2109, Australia
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Fig. 1. Structure of the VIDEO and ANIMATED tail-flick sequences. (A) Plots of the
Euclidean distance (mm) between the tip of the tail in each frame (PAL
standard: 40 ms), and its position in the first frame of the sequence. (B)
Speed and (C) acceleration for each sequence. Values are means +
S.E.M. (N=162 frames).
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Fig. 2. Representative frames from the VIDEO (left) and ANIMATED (right) sequences.
The black mask on the right side of each frame has been cropped.
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Fig. 3. Response latencies for the VIDEO tail-flick and the ANIMATED replica.
Values are means + S.E.M. (N=18).
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Fig. 4. Display action patterns for the four stimulus sequences used in Experiment
2. Lines represent the Euclidean distance (mm) between the tip of the tail in
each frame, and its position in the first frame of the sequence. Plots are
shown from the shortest sequence (FAST; top) to the longest sequence (SLOWER;
bottom). Note that the time base varies to accommodate changes in stimulus
duration. Sequence length relative to NORMAL is indicated in each panel.
Horizontal bars represent the response latency (mean ± 1
S.D.).
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Fig. 5. Representative frame showing the vegetation used as the background in
Experiments 2–4 (left), and an enlarged view of the tail against the
background (right).
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Fig. 6. Probability of an orienting response to Experiment 2 sequences, in which
the tail-flick time-scale was manipulated (*P<0.05;
**P<0.01). For details, see text.
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Fig. 7. Tail-flick sequences used in Experiment 3. All stimuli had the same
duration, but they varied systematically in tail-flick amplitude and number of
reversals. The tail position in each frame of the upward sweep of the
tail-flick is shown together with display action patterns.
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Fig. 8. (A) Probability of an orienting response and (B) latency to respond to
Experiment 3 sequences in which tail-flick amplitude was manipulated. Values
are means + S.E.M.
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Fig. 9. Display action patterns for the tail-flick sequences used in Experiment 4.
(A) These comprised a 2x2 matrix of duration (columns) and speed (rows).
(B) An additional stimulus with intermittent movement was presented to test
the effect of a reduced duty cycle. See text for details.
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Fig. 10. Probability of an orienting response to Experiment 4 sequences, which
varied in terms of speed, duration and duty cycle
(*P<0.05; **P<0.01).
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Fig. 11. Factors likely to have contributed to the design of the Jacky dragon
tail-flick. The sensory properties of receivers (A) and the environmental
conditions (B), interact to define signal conspicuousness. Important
characteristics of receiver behaviour (C) include compensation for a limited
(<360°) visual field by constant scanning of the environment and
engagement of visual processing by other stimuli, such as predators and insect
prey. These factors predict increased signal duration. Energetic cost (D) has
probably selected for a reduced duty cycle. In addition, the tail-flick is
less likely to compromise anti-predator responses than other motor
patterns.
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© The Company of Biologists Ltd 2003
