The name is absent

SPATIAL REORIENTATION IN MONKEYS

Table 8

Number of Trials (Out of 50) During Experiment 7 for the
Subjects as a Function of Their Search Location (Correct,
Rotational, Geometrically Inappropriate Corners)

Box

Note. C = correct; R = rotational; N = near misses; F = far misses.

test computed on the data obtained in the observed geometrically
appropriate category (Comers C and R), compared with an equal
frequency of distribution of the searches to these two corners (i.e.,
50% of chance for each one), indicated that the number of visits to
Comer C and to Comer R were statistically different, Crevet, X2(1,
N = 48) = 25.13; Krill, ~2(1, N = 46) = 12.00; p < .001, showing
that the monkey correctly located the reward after being
disoriented.

The subject reacted in the same way during the virtual rotation
control session. On average, 80% of the first visits during the 10
trials were focused on the rewarded box (Box C: 70% for Krill and
90% for Orcas). The geometrically equivalent comer (Comer R)
received on average 15% of the first visits (20% for Krill and 10%
for Orcas). Finally, the geometrically inappropriate comers (noted
"N' and "F„) received on average 5% of the first visits (10% for
Krill and 0% for Orcas).

As for the previous experiments, the results of the first 10 trials
for each subject are shown in Table 2 (Experiment 7). Analysis of
the individual data compared with the performance obtained for
the 50 trials of Experiment 7 indicates no statistical difference,
Krill, X(1, N = 60) = 2.58; Crevet, X2(1, N = 60) = 0.01; p >
.05. These results show no evidence for an improvement of the
performance across the experimental session.

Discussion

The monkeys were able to search in the correct corner as early
as the fast trial. Thus, they must have used the single cue to
reorient and to disambiguate the correct corner from the geomet-
rically opposite corner. The control condition confirms that no
other cue than the landmark, inside or outside of the apparatus, was
used by the subjects to retrieve the target.

Experiment 8

This last experiment was run to test the importance of the cue
size compared with its location (comer or wall) for reorientation.
For that purpose, we decided to test the subjects with the same
angular cue configuration used in Experiment 5 but with a larger
cue size. If the cue size is important (and not its location), then the
subjects are expected to succeed in correctly locating the rewarded
corner in contrast with what subjects did in Experiment 5.

Method

Subjects. As in the previous experiment, only 2 subjects passed this
experiment because Subject Orcas stopped searching for the reward. Be-
tween Experiments 7 and 8, a delay of 2 months occurred.

Apparatus. The same apparatus as in Experiment 5 was employed,
except that the landmark used in that experiment was of intermediate size
(50 cm X 60 cm) between the large one used in Experiment 2 and the small
one used in Experiment 6 (see Figure 4). The cues were located in each one
of the four comers of the experimental apparatus.

Procedure. The procedure was identical to the one used in the previous
experiments, except that a 10-trial control session was given at the end of
the 50 trials run per each subject. It consisted of a 180° rotation of the four
corner cues and the rewarded box as in Experiment 2. The purpose of this
control session was to check that the information used by the subjects to
reorient was only provided by geometry of the room and the four different
corner cues.

Results

Table 9 presents the number of first-choice searches performed
by the 2 subjects during the 50 test trials. For each monkey, the
data were subjected to a chi-square one-sample test in which we
compared the observed distribution in the geometrically appropri-
ate and geometrically inappropriate categories to the theoretical
frequency of an equal distribution of these two categories (i.e.,
50% of chance for each one). These results always reached statis-
tical significance, Crevet, X2(l, N = 50) = 32.00, p < .001; Krill,
X2(1, N = 50) = 28.88, p < .001. A second chi-square one-sample
test computed on the data obtained in the observed geometrically
appropriate category (Corners C and R), compared with an equal
frequency of distribution of the searches to these two corners (i.e.,
50% of chance for each one), indicated that the number of visits to
Corner C and to Corner R were statistically different, Crevet, X2(1,
N = 45) = 21.35, p < .001; Krill, ,y2(1, N =44) = 13.1, p < .001.
This suggests that monkeys mainly chose the correct comer.

During the virtual rotation control session, all subjects reacted in
the same way. On average, 85% of their first choice during the 10
control trials were directed to the rewarded box (noted "C"; 80%
for Subject Crevet and 90% for Subject Krill). The geometrically
equivalent comer (noted "R") received an average of 10% of the
first visits (20% for Subject Crevet and 0% for Subject Krill).
Finally, the geometrically inappropriate comers (noted "N" and
"F„) received, during this control session, an average of 5% of the
first visits (0% for Subject Crevet and 10% for Subject Krill).
These results suggest that no cue (inside or outside the experimen-
tal apparatus) other than the four different colored cues were used
by the subjects to reorient.

Table 2 (Experiment 8) provides the results for each subject
during the first 10 trials. The individual scores observed for
these 10 first trials are not different from the scores obtained

Table 9

Number of Trials (Out of 50) During Experiment 8 for the
Subjects as a Function of Their Search Location (Correct,
Rotational, Geometrically Inappropriate Corners)

Box

Note. C = correct; R = rotational; N = near misses; F = far misses.

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