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merited by limb flexion and extension) which 
are at times interspersed with periods of no 
amplitude change. Variables which can cre- 
ate dilferent appearing displays are: direc- 
tion of head movement (up or down), rate 
of head movement (constant or changing), 
relative amplitude of the movement, and 
elapsed time between movements. With 
anoles, dewlap movement can be coordinated 
with head movements. The physical and 
functional aspects of displays are referred to 
by the terms “display pattern” and “display 
type.” 
Display Pattern 
Display pattern is a descriptive term used 
to refer to the change in amplitude through 
time of a lizard’s head and dewlap as the 
lizard performs a head bob display. As a rule, 
the pattern is reoccurring for a species which 
indicates it is stereotyped. It is basically the 
same as Carpenter’s (1967: 96) “display- 
action-pattern” (DAP). A display pattern 
can be analyzed according to its “units” (sub- 
divisions of a display’s movements), “se- 
quence” (the ordering of units), and 
“cadence” (relative unit durations). Plotting 
head and dewlap amplitude changes (Y-axis) 
through time (X-axis) from films or video- 
tapes results in a display-action-pattern 
graph (DAP graph). 
Display Type 
Display type is a primary category. 
It encompasses: (1) the stereotyped head 
and/or dewlap movement pattern (i.e., 
stereotyped display pattern), (2) any con- 
sistently associated stereotyped movements 
by other body parts (e.g., tail lift), (3) any 
other postures and movements which less 
consistently accompany the stereotyped dis- 
play pattern, and (4) the functional signifi- 
cance. 
It is assumed each display type has a 
unique function, although a single display 
type may appear in more than one social 
context, suggesting that it has more than one 
function. In contrast, more than one display 
type may be performed by an individual 
within the same social context. 
Display Modifier 
Display modifier is a posture or body move- 
ment which is not always present with a 
particular stereotyped display pattern, but 
at times is added to the pattern. The concept 
is useful in classifying the variability found 
between displays by helping to distingush 
what different display types are and what 
variations of the same display type are. A 
modifier may be static (a posture) or dy- 
namic (body movement) which is not always 
associated with a particular display type, but 
can be added to the permanent elements of a 
display type as an option employed by the 
entire population (Jenssen, 1977&; Jenssen 
and Hover, 1976). Static modifiers are such 
postures as raised nuchal crest, lateral com- 
pression of sides, open mouth, and a sus- 
tained posture during a display such as 
elevated on all four legs. Although not 
strictly a posture, color change might also 
be considered a static modifier. 
A dynamic modifier can be (1) optional 
head and/or dewlap movements added just 
prior to the stereotyped core display, (e.g., 
introductory rolling movement of head pre- 
ceding the A display of A. limifrons; see Fig. 
8; (2) optional head and/or dewlap move- 
ments occurring at the end of the stereotyped 
core display (e.g., repetitious bobs following 
first seven head bobs of A. limifrons signa- 
ture display, see Fig. 8) ; or (3) any occa- 
sionally incorporated movement of the body 
part besides the head or dewlap which is 
concurrent with the display (e.g., tail lifts 
during signature display of Anolis breviros- 
tris; pers. observ. 
Assertion, Challenge, and Signature 
Displays 
Carpenter (1962, 1967) coined the terms 
“assertion” and “challenge” to describe a 
