A young woman sits in front of a computer, joystick in hand. On the screen in front of her is a large circular pool of water, which she “wades” through by moving the joystick. She is attempting to find a platform hidden just beneath the surface of the water, and as she wanders through the pool, she notices that there are objects scattered around the edges of the room. Some large red columns sit on one side, next to a group of bushes. On the other side are a television set and a brown crate. As she moves in the direction of the crate, she suddenly finds herself on top of the hidden platform. She looks around to orient herself, and then the experimenter restarts the game. On the second trial she wades through the same pool of water, only this time she does not wander aimlessly. Remembering the landmarks from before, she immediately walks towards the crate, then turns to the center of the pool. She walks forward a few paces to find the hidden platform and smiles in satisfaction.
One of the most enduring ideas in folk psychology is that men and women somehow differ in their ability to get from place to place. According to this stereotype, men have an innate sense of absolute direction, while women rely on landmarks for guidance. The scientific hypothesis underlying this stereotype is that men and women may use different sorts of information when navigating through the world; men may use geometric or spatial aspects of the environment, such as direction and distance, while women may use objects in the environment, such as signs and buildings. This hypothesis has been primarily tested in rats, where it has been shown that when learning the layout of a maze, male rats encode geometric information about the room dimensions and female rats encode both geometric information and landmark information.
Although these ideas are pervasive, they are difficult to test experimentally in humans. Construction of a small, rat-sized maze is simple, but construction of a maze large enough for adult humans to explore would be quite challenging and expensive. Using existing environments, such as buildings and college campuses, creates its own set of problems; it is hard to move a university water tower between experimental trials! To overcome these problems, Dr. Noah Sandstrom, Dr. Jordy Kaufman and I investigated gender differences in human spatial navigation ability using virtual, computer-generated environments.
We created a computer simulation of the Morris Water Maze, a type of environment used to study spatial navigation in rodents. The standard water maze is about the size of a child’s wading pool and is filled with murky water so that the rat cannot see beneath the surface. A small platform is placed in a random location in the pool, and a rodent must swim around in the pool until he discovers the hidden platform. Rodents can use visual cues around the room to help them remember where the platform is located, so when they’ve found the platform once, they have an easy time finding it again.
To investigate what information the rats may be using to find the platform, the experimenters can manipulate aspects of the surrounding room. If a circular curtain is placed around the pool, no information about room shape is available to guide the rats’ search. Alternatively, if the experimenters bring in different objects into the room, such as computers or desks, the rats can use the locations of those landmarks when searching.
In our virtual water maze experiment, we had students play a computer game in which they searched for a hidden platform in a large pool of water. The pool was located within a large, trapezoidal room containing four landmarks: a crate, a television, some columns, and some bushes (figure 1). The platform was always in the same location in the pool, and when the players found it music and animation rewarded their success.
The goal of our experiment was to find out what visual cues men and women use during spatial navigation. Were the students relying on an absolute sense of direction based on the shape of the room, or were they finding the platform in relation to the landmark objects? To answer those questions, we designed an experiment with two phases. In the Training Phase, students were asked to play the game six times. Each time they played they started from a random location in the virtual room, but the room itself was unchanged. The goal of the Training Phase was to teach the students how to locate the platform quickly and accurately.
In the Testing Phase, we wanted to find out what visual cues the students used to find the platform. The students were again asked to play the game six times, but now we changed the visual cues in the room. For one group of students, we made the room completely circular but left the landmark objects in place; we called this the Landmark condition, because students had to use landmarks instead of the room’s shape to navigate. For a second group of students, we kept the room’s shape unchanged but removed all of the landmark objects; we called this the Geometry condition, because students had to rely on the shape of the room alone to locate the platform. For the last group of students, we kept the room’s shape the same but randomly rearranged the landmark objects each time they played the game; this was the Random Landmark condition.
Our results suggest that men and women are equally good at navigating through complex environments. All of the students took an average of 60 seconds to find the platform the first time they played the game, and all of them improved with practice. By the sixth and final Training trial, all of the students were able to find the platform almost immediately.
Although these results alone suggest that navigational ability is unrelated to gender, the data from the Testing trials tells a different story. While men and women are equally good at moving through complex environments, they do appear to use two different navigation strategies. Men and women did equally well in the Landmark condition, indicating that both sexes used landmark objects to find their way around the pool. However, when the landmarks were not available or not reliable, as in the Geometry and Random-Landmark conditions, men on average performed significantly better than women in finding the platform. Gender differences in spatial navigation seem to result from differential navigational strategies: women pay more attention to landmarks while men tend to take cues from geometrical relationships.
In addition to shedding light on gender differences in spatial navigation, the results of this experiment demonstrate that techniques developed for studying animal behavior can be successfully used to study human behavior. Computer simulation and clever experimental design can translate tasks like the Morris Water Maze into the human dimension, allowing greater cross-correlation between human and animal studies. As we explore the neurobiological sources of sex differences, collaboration between researchers studying animal development and researchers studying human abilities will be critical.
References:
Sandstrom, N. J., Kaufman, J., & Huettel, S.A. Males and females use different distal cues in a spatial navigation task. Cognitive Brain Research, Vol. 6 (1998), 351-360.
W.H. Overman, B.J. Pate, K. Moore and A. Peuster, Ontogeny of place learning in children as measured in the radial arm maze, Morris search task, and open field task, Behav. Neurosci., Vol. 110 (1996) 1205-1228.
C.L. Williams, A.M. Barnett and W.H. Meck, Organizational effects of early gonadal secretions on sexual differentiation in spatial memory, Behav. Neurosci., Vol. 104 (1990) 84-97.
