Chapter 1, The Reptilian Spectacle - UWSpace - University of ...

Presence of
blood flow }
Presence of
blood flow }
0 10 20 30
0 10 20 30
Time (min)
2.3.2 Effect of threat perception on spectacle flow
Figure 2-7 (next page) illustrates the effects of threat perception on spectacle blood flow in two
representative trials. During the 8 minutes of perceived threat, the mean duration of individual flow
events was reduced to 33.5 s (standard deviation: 17.6 s), down from 57 s, when data from all subjects
were pooled. As well, the total proportion of time during which flow occurred was reduced when
compared with the 8 minutes prior to and after the presented threat (p = 0.011). No difference was
found between trials (p = 0.633) nor between the first and second threat events within a trial (p =
0.150). Interaction terms between any or all of the 3 factors were also found to not be significant.
Figure 2-8 (next page) shows a box plot of the proportion of time during which blood occurred before,
during, and after each threat event.
45
Figure 2-6. Two example
trials showing blood flow
patterns in undisturbed
snakes. Blue dashes indicate
when spectacle blood flow
was apparent in the initial 30
minute undisturbed phase of
two separate snakes.