The name is absent

SPATIAL REORIENTATION IN MONKEYS

result suggests that the subjects used no cue (inside or outside the
apparatus) other than the blue wall to reorient.

Discussion

The present results are in agreement with those obtained with
human adult subjects (Hermer & Spelke, 1994, 1996). They clearly
indicate that monkeys confined their search to the correct corner
box with high consistency. Because only the presence of the blue
wall distinguished this environment from the homogeneous envi-
ronment of Experiment 1, and because the control session was
successfully realized, this finding indicates that our monkeys were
still able to take into account the nongeometric property of the
environment in their search strategy.

However, monkeys may have located the rewarded box either
by a combined use of geometric and blue-wall information (by
simultaneously noticing that the reward was hidden in a corner
with appropriate geometry and that it was hidden near the blue
wall) or by directly encoding the relation of the reward to the blue
wall (by noticing that the object was hidden to the left or right of
the blue wall). To test for these two possibilities, we dissociated,
in a third experiment, the reward box and the landmark to see
whether the monkeys were able to retrieve the correct box.

Experiment 3

In Experiment 3, we tested the monkeys' ability to reorient in
accord with both the shape and the nongeometric cue of the room
when this cue was not directly associated with the reward.

Method

Subjects. The same 3 subjects were used in Experiment 3. Between
Experiments 2 and 3, a delay of 1 month elapsed.

Apparatus. The apparatus was the same as used in Experiment 2
except that one of the small walls of the apparatus, instead of a plain blue
panel, was checkered by several black panels (65 cm X 60 cm). The panels
always occupied the opposite side with respect to the rewarded box (see
Figure 2).

Procedure. The same procedure as in Experiment 2 was used, includ-
ing the 10 control trials at the end of the experiment.

Results

Table 4 presents the number of first searches performed by the 3
subjects during the 50 test trials of Experiment 3. For each mon-

Table 4

Number of Trials (Out of SO) During Experiment 3 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.

key, the data were subjected to a chi-square one-sample test in
which we compared the observed distribution to the theoretical
frequency of an equal distribution in the geometrically appropriate
and geometrically inappropriate categories (i.e., 50% of chance for
each one). These test results always reached a statistically signif-
icant level, Orcas, X2(1, N = 50) = 38.7; Krill, X2(l, N = 50) =
^{50.0; Crevet,} X2(1, N = 50) = 46.1, all ps < .001. A second
chi-square one-sample test computed on the data obtained in the
observed geometrically appropriate category compared with an
equal frequency of distribution of the two corners of that category
(i.e., 50% of chance for each one) indicated that the number of
visits to Comer C and to Corner R were statistically different,
Orcas, X(1, N = 47) = 26.06, p < .001; Krill, X2(1, N = 50) =
6.48, p < .025; Crevet, X2(l, N = 49) = 34.30, p < .001.

For Experiment 3, the results obtained by each subject, during
the entire experimental session (50 trials), are not statistically
different to those observed during the first 10 trials (see Table 2,
Experiment 3), Orcas, X2(1, N =60) = 1.67; Krill, X2(l, N =60)
^{= 0.36; Crevet,} X2(l, N = 60) = 0.48; p > .05. Thus, we can
conclude that no obvious improvement of the monkeys' perfor-
mance takes place across trials.

During the virtual rotation control session, all the subjects
reacted in the same way. On average, 83% of their first choices
during the 10 sessions were directed to the rewarded box (box
noted "C"; 90% for Orcas, 80% for Krill, and 80% for Crevet). The
geometrically equivalent comer (Corner R) received 13% of the
first visits on average (0% for Orcas, 20% for Krill, and 20% for
Crevet). Finally, the geometrically inappropriate corners (noted
"N" and "F") received an average of 3% of the first visits (10% for
Subject Orcas, 0% for Subject Krill, and 0% for Subject Crevet).

Discussion

As in the previous experiment, the correct corner box was
predominantly chosen, in preference to the rotational equivalent
corner. Our data confirm that monkeys are able, like human adults,
to combine both the geometric properties of the room and non-
geometric information to locate a target when they are disoriented.
Moreover, in this experiment, nongeometric information was not
directly associated with the rewarded box. Thus, we can conclude
that monkeys located the rewarded box by combining both geo-
metric and nongeometric information instead of directly encoding
the relation of the reward to the landmark (i.e., by considering that
the reward was hidden to the left or right of the landmark).

Part 2

Assuming that the monkeys were able to use both geometric and
nongeometric information to reorient themselves in the experimen-
tal room (as shown by the previous experiments), we further
investigated that specific spatial ability. Thus, Experiments 4 and 5
were designed to determine whether the monkeys are sensitive to
more local spatial information, such as corner cues, and whether
they are also able to use local cues dissociated from the goal (distal
cues) to orient themselves.

Experiment 4

Experiment 4 was aimed at determining whether monkeys use
four distinctive small corner panels to specify a place, and,

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