218 
Greenberg 
( 
TIME 
Figure 13. The curves for three lizards suggest a diurnally varying thigmotactic tendency. Lizards were 
scored on the basis of posture and activity — with the highest score going to sleeping animals with their 
heads wedged into crevices. Triangle = female, closed circle = subordinate male, and open circle = dom- 
inant male. 
ing an abundance of prey (Evans, 1951 ; 
Fitch, 1940; Norris, 1953). 
Social behavior has received much atten- 
tion by students of saurian behavior — pos- 
sibly because of the early attention drawn to 
the work of Noble and Bradley (1933) by 
Lorenz (1935). Since Carpenter’s (1962) 
introduction of the “display action pattern” 
analysis display activity has been subject to 
intense research (Jenssen, this volume). 
Context is of importance in an interpre- 
tation of either arousal (operationally de- 
fined by postures and activities) or the com- 
municative significance of a display. W.J. 
Smith (1969) points out that since there are 
more functions served by displaying than 
there are displays, recipients of displays 
must rely heavily on contextual information. 
The possibility of a discontinuity in the 
physiological causation of superficially simi- 
lar displays that appear in various contexts 
must be considered. 
A prevalent view is that the bobbing dis- 
plays of iguanids include two types which 
represent a continuum of “intensity” (Car- 
penter, 1967). These displays are designated 
“assertive” and “challenge”; the former is 
performed in social and nonsocial situations 
and may be elicited by a broad range of 
stimuli; the latter is performed as part of 
ritualized territorial defense. The possibility 
of a gradient between these displays recalls 
Moruzzi’s suggestion that different responses 
are possible at different arousal levels (cited 
by Andrew, 1974). Stamps and Barlow 
(1973) have analyzed the display behavior 
of Anolis aeneus and observed that while 
some components may indicate a gradient 
of “intensity” between displays, in general, 
no smooth continuum exists between the 
