Learning in Lizards 
179 
tain food, warmth, or shelter. It has been 
shown, for example, that mice familiar with 
an environment were more successful in es- 
caping from a screech owl than those with- 
out any experience in the same habitat. The 
experienced mice escaped into burrows that 
were never formerly used (Metzgar, 1967). 
Such “unrewarded” learning has been re- 
ferred to, perhaps erroneously, by some zool- 
ogists as “latent learning.” Brant and 
Kavanau (1964) ran both wild and labora- 
tory mice in very complex mazes and found 
that most of them spent considerable time 
exploring. In addition to familiarizing an 
animal with its habitat, this activity may be 
self rewarding in terms of metabolic require- 
ments. 
To test for the possibility of “unrewarded” 
learning in lizards, Fonda and I utilized a 
complicated maze (Fig. 2) that had sensing 
devices for recording the place and times of 
the lizard’s movements. Each of three wood- 
covered compartments (#1, 9, 13) had a 
15 w incandescent light. The entire maze 
was illuminated by an overhead 100 w in- 
candescent light bulb and the room tempera- 
ture was 21±2°C. Twenty-two lizards, Scelo- 
porus occidentalis, were placed, one at a time, 
in compartment 11 of the maze and left for 
23 hours. The lizards were not observed dur- 
ing this period. A lizard was then removed 
and cooled at 10°C for 5 minutes, after which 
Figure 2. Diagram of the maze used to study “un- 
rewarded” learning in the western fence lizard, 
Sceloporus occidentalis. Numbers represent 
treadles that monitored the lizard’s movement. 
Lizards were released into the maze in chamber 
11 at R. 
it was replaced in area 11. Lizards were re- 
moved when they reached a heat source or 
after 30 minutes (see Table 3). Of the 22 
subjects, 87 percent went directly to a heat 
source (usually within 5 minutes), and of 
these 55 percent went the shortest way 
(compartments 11, 12, 13). While in the 
maze the first time, these animals presum- 
ably explored the maze, encountered the heat 
lamp, and were thus rewarded. When cooled 
and returned to the maze, their retention of 
the information about the maze allowed them 
to go directly to the heat source. Whatever 
the behavioral response is called, the signifi- 
cant fact is that lizards explore their environ- 
ment, learn it well, and are able to use the 
information on subsequent occasions. 
CONCLUSION 
It is clear that lizards can learn a variety 
of tasks, exhibit different types of learning, 
and learn most readily when provided with 
ecologically relevant reinforcement. The 
kind of experiments reported here can be 
useful to three types of investigators. 
Psychologists would find such experiments 
helpful in shedding light on conventional 
problems. Neuroanatomists and neurophysi- 
ologists will find the experimental procedures 
useful in investigating neurological corre- 
lates of behavior. Ecological behaviorists can 
utilize learning studies for gaining a further 
TABLE 3 
“Unrewarded” maze learning in the western 
fence lizard, Sceloporus occidentalis. Results 
of 22 lizards’ performance after exploration 
of a complicated maze for 23 hr. with three 
heat sources, subsequently cooled at 10°C 
for 5 min. and returned to the maze. 
Number Percent 
Lizards going directly 
to heat source: 19 87 
Lizards never reaching 
heat source in 30 min. 2 9 
No movement 1 4 
