REORIENTATION BY SLOPE CUES IN HUMANS

1
REORIENTATION BY SLOPE CUES IN HUMANS
Daniele Nardi, Amanda Y. Funk, Nora S. Newcombe
Thomas F. Shipley Temple University
Fig. 5 Number of correct choices during the tests.
As expected, when tested on a flat surface (i.e.,
without any cue), participants were disoriented
and could not locate the correct corner more than
by chance. However, when tested on the slope,
both males and females performed significantly
above chance (binomial test, males p lt .0001
females p lt .05).
Introduction

• The enclosure was completely symmetrical and
  featureless, and no external cue could be seen or
  heard (participants wore earphones). Therefore,
  the only way to encode and locate the goal was
  using the slope gradient, i.e., encoding the goal
  with respect to the vertical and orthogonal
  (left-right) axes of the slope (e.g., the target
  is in the upper-left bowl see Fig. 2).
• Training was composed of 4 trials, with the
  target always in the same place.
• Subjects were given feedback and shown the target
  at the end of the trial.
• On each trial subjects started facing a different
  side of the enclosure.

Animals are remarkably skilled in their capacity
to use a range of environmental features to
orient in space once they have lost track of
where they are, a process called reorientation.
Among the types of cues that animals can use, one
that has received little attention is the
directional information extractable from a
surface extending in the vertical dimension, such
as a geographical slant or slope (Restat, Steck,
Mochnatzki, Mallot, 2004 Miniaci, Scotto,
Bures, 1999 Proffitt, Bhalla, Gossweiler
Midgett, 1995). Slope is a perceptually salient
cue because it provides potentially redundant,
multimodal sensory activations, such as visual,
proprioceptive, kinesthetic and vestibular
stimuli. However, studies have shown that the
conscious awareness of slope seems to be highly
variable, depending, for example, on
physiological and psychosocial resources
(Proffitt, Bhalla, Gossweiler Midgett, 1995
Schnall, Harber, Stefanucci Proffitt, 2008).
The present research aimed to study, for the
first time in a real-world environment, the
extent to which humans can use a geographical
slant for successful reorientation and goal
location.
Chance
These results rule out the possibility that
participants were using cues other than the slope
to solve the task. Only when the enclosure was
slanted could subjects reorient and successfully
locate the target.
UPHILL
Fig. 2
Fig. 3
Participant
Fig. 6 Participant self-report strategy use.
Bowl
More males than females reported using slope to
locate the target, Fishers exact test, p lt .05.
This suggests that males outperform females
because they are more likely to use slope to
solve the task.
DOWNHILL
Males
Females
Testing Subjects left the enclosure and came back
two times for the tests (one trial each, with no
feedback). Tests were presented in
counterbalanced order. Flat test. For one trial
the enclosure was placed horizontally on the
floor ? No polarizing cues were available that
would enable to distinguish a specific corner ?
Expected performance is at chance (25). Slope
test. For one trial the enclosure was tilted
again at a 5 inclination ? Participants could
now locate the target.
Method
Male scores in the water-level task were
significantly higher than females, t(38) 2.13,
p lt .05. There was a significant correlation
between water-level and slope task performance,
r(38) .36, p lt .05. However, when controlling
for gender, the correlation was not significant,
r(37) .22, p .18. This suggests that
water-level and slope task performance correlate
because males are better than females in both
tasks.
PVC pipe frame
Fig. 1
Wooden platform
Conclusions
Obtuse
At the end of the experiment subjects completed
the water-level task (Piaget Inhelder, 1956)
and reported what information they used to locate
the target -Slope (using the slope
gradient) -Other (using path integration or any
feature cues, e.g., wrinkles in the
curtains) -View-based (using the different angle
of incidence between the uphill and downhill
curtains with the platform).
Acute
Both males and females are able to use the slope
of the floor to reorient and locate a hidden
goal. However, there is a large gender difference
in performance because females are less likely to
spontaneously use slope cues than males. Males
also outperform females in the water-level task,
and a similar result has been shown in other
visual perception tasks that require engaging the
horizontal-vertical reference frame (Linn
Peterson, 1985). However, the present finding is
important because it shows a male superiority in
the use of a multimodal cue in which kinesthetic
and vestibular information as opposed to visual
information play a crucial role. Future
research will have to investigate the factors
underlying the gender difference in slope use,
and whether this female deficit might be
eliminated by drawing more attention to the fact
that the floor is tilted. This research was
supported in part by National Science Foundation
funding of the Spatial Intelligence and Learning
Center (SBE0541957). For further information
please contact daniele_at_temple.edu. More
information on this and related projects can be
found at http//spatiallearning.org/
ON A HORIZONTAL SURFACE
WITH A 5 SLOPE
Apparatus The experimental enclosure consisted
of a square, wooden platform with a PVC pipe
frame on top (overall size of the enclosure
base, 244 x 244 cm height, 206 cm see Fig.1-3).
Curtains were placed around and on top of the PVC
frame, such that the experimental environment was
completely enclosed. The enclosure could be
placed horizontally on the floor, or could be
tilted to a 5 inclination. Illumination was
provided by four 25-W lamps on the platform, one
in each corner. Four red bowls, used as
potential hiding places for the target, were
located in the corners. A swivel chair was placed
in the center of the enclosure (even when the
enclosure was slanted, the chairs axis of
rotation was always perpendicular to the
earth). Training 20 males and 20 females took
part to the experiment. The enclosure was slanted
with a 5 inclination. The participant saw the
experimenter hide the target (a 1 bill) under
one of the four bowls. Then the participant was
blindfolded and spun on the swivel chair for 1
minute. During this time, the experimenter moved
around the curtains so that subjects could not
use the wrinkles to determine the goal location.
After being disoriented, participants had to tell
where the target was hidden.
Results
Fig. 4 Mean correct choices ( SD) during the 4
training trials.
Both genders performed above chance, males t(19)
14.33, p lt .0001 females t(19) 2.41, p lt
.05. However, males performed substantially and
significantly better than females, t(38) 4.43,
p lt .0001. This effect size is large, d 1.4,
with means differing for more than 1 SD.