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Spatial Cognition
Spatial Cognition is the subfield of cognition concerned with the mapping of space, exterior or interior to the human individual, the recognition of this space and the recall based on memory of spatial information. The relationship between Spatial Cognition and other aspects of cognition, in particular animal cognition, will be explored in as far as such related studies contribute to the advancement of spatial cognition.

Origin in Philosophy
The French philosopher, René Descartes, formulated "Cogito ergo sum," which is Latin and means "I think, so I am." This statement is used in philosophy to define the boundary between the conscious mind of a person and the external world with which this person interacts. The mind itself is not seen as occupying a perceived space-even though the frontal lobes of the person's brain have a spatial extension-, but serves as a reference position (point) in the sense of the origin of a Cartesian coordinate system spanning space. The grand total of things with which the mind of the person then interacts, comprises the objects that fill the physical space - either the space within the person's body (like the position of his or her hands relative to the perceived origin) or space beyond the boundaries of the human body. The distinction of these two spaces becomes important when the person wants to move; motion is relative to the outer, physical space but is achieved by coordinating the relative motion of body parts, such as hands and feet.

Origin in Physics
Sir Isaac Newton was the first to develop physical laws that govern the relationship of parameters that identfy an object's position and motion in the outer, physical space. He showed that acceleration, or the change of velocity, requires a force acting on the object, which could be a physical boundary (like an apple doesn't fall off a table because the table exerts a normal force upwards on the apple) or a willfully exerted force that then requires a directing mind (the "I" in Descartes model). Other parameters do not require forces to be exterted, in particular the position or the state of velocity at any given time. While physics therefore gives primary importance to acceleration, our attention is much more focussed on velocity and position as these parameters can be measured more readily by visual observation. Newton's laws of mechanics also apply to the locomotion, but because this is the person's control over the inner space it is a primarily biological context.

Relations to Biology
To achieve motion, forces are exterted by muscles on the bones of the skeletal system. The muscles are attached to two different bones that meet in a joint, like the elbow. To move, a skeletal muscle must be contracted, causing a rotation of the bone further from the person's trunk about the axis of rotation. The resulting motion is explained by the same laws of mechanics which were discussed in the previous section. Physical space can be described by various mathematical coordinate systems, such as cartesian coordinates, cylindrical or spherical coordinates. The biology of locomotion of vertebrates therefore provides an interesting discrepancy: the motion is based on rotation of bones about an axis, which is mathematically best captured by polar coordinates in the plane of motion. However, the human brain perceives space always as Cartesian because we measure our acceleration in three semicircular canals in the vestibular organ of the inner ear. The three semicircular canals are perpendicular to each other, consistent with a Cartesian coordinate system.

The Connection to Cognitive Science
A convergence of the different origins of the discussion of space started with Gustav Fechner at the end of the nineteenth century when he defined the term Psychophysics. The existence of the journal Perception and Psychophysics, which contains several articles important to the field of spatial cognition, shows that studies at the interface of Physics, Biology and Psychology are still converging with new discoveries.

The Three Spaces of Spatial Cogntion
The physical space is divided into three distinctive units in spatial cognition: the space in which we navigate, the space immediately surrounding our body and the space within the human body. These three spaces form a continuum during locomotion, but are conceptualized in different ways.

The space within which we navigate is distorted as it is reduced to elements that relate to each other (e.g. a road to the mountains nearby). Low attention is paid to quantitative relations, leading in particular to misjudgments on travel times and distances. The space around the body is categorized in relation to the main symmetry axes of the human body, and is perceived then as an extension of those axes. Objects in this space are searched for based on these previously established categories; leading to relative instead of absolute spatial cognition. The speed of naming or recognizing a body part is linked to the perceived or actual importance of the respective body part. Thus all three spaces are not mentally accessed as simple Euclidian geometry in which either Cartesian coordinates or polar coordinates would be stored as absolute measures relative to a consistently defined origin. Instead, categories are used, including the body schema internal to the person, and spatial cognition is based on relative and often just qualitatively known locations.

Use of Landmarks in Animals
Animal vision, like our vision, is ambiguous due to the conversion of a three dimensional Gestalt (shape) to a two-dimensional image on the retina, followed by a digitizing conversion into nerve signals that travel along the optic nerve. The brain does not store a pixel-based image, but rather produces symbols for shape, contour, colour, brightness and image motion. When the individual pays attention, these various components of the original object are brought together in the frontal lobes and are compared to previously stored symbols, i.e., they get checked against memory for recognition. Animals that migrate or control a large territory need effective methods of navigation.

Migratory birds apply three systems for navigating large spatial distances. First, they employ two systems of landmark recognition - one based on visual cues, such as mountains and lakes, and one based on the position of stars. Secondly, birds have small magnetic sensors in their brain which allows them to measure the direction of the Earth magnetic field The use of three systems rather than one guarantees error-free navigation over widely varying terrain, e.g., when flying over the Great Lakes in Canada.

Animals with shorter travel routes rely on fewer cues. These are most typically visual cues, which we define in this context as landmarks, however, can be olfactory cues as shown in recent studies. For example, ants combine these two systems, using primarily visual cues when in need to travel fast, but rely on olfactory cues when close to their target position.

Object Recognition
In order to understand the nature of objects, we need to understand spatial perception first. This is due to the spatial, physical nature of objects. The primary means of discovering spatial properties of objects are through vision and touch. It is believed that when aspects of objects are spatially encoded, the brain converts them into mental representations of perceptual modalities (e.g. Visual systems, auditory systems, etc) which become accessible to the conscience of the human. This process allows humans and animals to realize that objects continue to exist even though they have been removed from our immediate surrounding accessible to our senses. This concept is called object permanence.

Various parts of the human body receive particular attention during human-human interaction. We pay particular attention to the face as it allows us to not only recognize other people, but also read their state of mind. In particular, the eyes and the mouth represent focal points for our vision. Eye movement and the use of the numerous small muscles that allow us to modify our facial features based on mood we want to convey are assessed in time-dependent mapping by others. Spatial perception allows an organism to estimate the location of an object on the basis of remembered landmarks. Landmark is defined for the current context as an object’s properties such as size and shape. Researchers in other fields in psychology have been studying behaviors of humans and animals with brain damage to achieve insight into the spatial organisation of neural modules that participate in visual recognition. One of the leading areas in this field is neuropsychology. Results of research in this field have taught us that lesions in the sensory-motor integrated parts produce spatio-perceptual and spatio-behavioural disorders. Patients with these disorders have difficulty with construction of activities that require spatial abilities such as drawing as seen in patients with apperceptive agnosia.

Body Mapping and its Relation to Physical Space
Our ability to imagine a spatial transformation is important for accomplishing many of our daily goals. A specific component of spatial cognition, which is likely to play a role in these goals, is an individual’s representation of his or her own body. The current understanding is that one’s representation of his or her body directly influences spatial cognitive processing. Hence, the label embodied cognition suggests that cognition is understood in the context of an active, physical body.

The role of body mapping in cognitive spatial transformation shows neural evidence of the recruitment of one’s body schema in motor imagery tasks. In 1998, building on this idea of body scheme, H. Branch Coslett of the University of Pennsylvania tested the performance of patients with right hemisphere lesions and patients with left hemisphere damage on a decision making task. He showed that the patients diagnosed with neglect showed impaired performance on identifying pictures of hand contralateral to their lesions. Today, cognitive and neural investigation of spatial tasks involving body and body part transformation have shown that mental representations of visually presented objects are likely tied to physical body representations or the body schema. Spatial representation involves a wide range of functions that allows people to competently accomplish everyday goals.

Similarities between humans and chimpanzees
Spatial Cognition is essential for all humans and animals. They must have the capacity to mentally represent the space through which they move and the path to follow through the wider space as well as the location of significant landmarks in the physical space. It is also necessary that we have the ability to update metal representations of spatial landmarks as a result of experience. Humans have created a variety of symbolic artifacts to support spatial cognition and action, thus we do not need to actually move around the world to form cognitive maps of space. We usually form functional mental representations using maps, globes, photo, etc. Thus, human are able to use symbolic representation in the perception of space.

Animals such as chimpanzee on the other hand, must rely on direct experience to form functional spatial representations. They imitate the actions of another animal acting in space. They therefore do not have a symbolic representation of space. However, current research has shown that when chimpanzees come in close contact with humans, they benefit from the symbolic representations of space. This research suggests that when chimpanzees are kept in our homes and are accustomed to interacting with humans, they are able to exploit information from symbolic representation of space by using scale models, similar to the way we humans do. The table below summaries the study by Sally Boysen and colleagues (reference) using a model scale task. The task involves showing a desirable miniature object and hiding it in a scale model, the participants are subsequently encouraged to go and find the object in the larger (real) space.

The table compares the performances of children and chimpanzees.

Conclusions from this research converge on the idea that adult chimpanzees and young children can successfully use a scale model as source of information for solving a search problem. These researches provide evidence that young children solve the task by mentally representing the higher-level, representational relation between the model and larger space it represents. The underlying mechanisms for chimpanzees are yet not very clear but these animals seem to just map the corresponding objects in the two spaces.

Limitations
Spatial limitations are defined as constraints on spatial cognition, primarily associated with visualization. Most typically, an object to the periphery of the field of view may not be noticed even though it is visible. Thus, we can define a spatial limitation as a boundary between recorded stimuli that are present in our conscience and those that are registered only unconsciously. The spatial limitations for a particular person are not fixed boundaries, that is, they don't occur at particular angles relative to the optical axis of the focused lens of the observer. Instead, our spatial limitations depend on non-spatial properties of the object under consideration, such as colour, shape, motion and brightness of the illumination of the object. Thus, spatial attention will expand further to the periphery of the field of view when object are colourful rather than uniformly coloured. These non-spatial properties will further depend on each other, for example in a dimly lit space, the role of colour will be diminished. The role of the nonspatial properties on spatial limitation can either occur in the physical transmission of stimuli (colour cones require higher light intensity than retinal rods) or in the psychological processing (attention to motion).

Future Research
The increased use of functional Magnetic Resonance Imaging and Positron Emission Tomography have connected the psychological interpretation of behaviour (mind) and the biological pathway processes (brain). These techniques allow for scanning of brain functions during well-defined tasks and can with great precision pinpoint functional connections and signal processing pathways in the human brain. This will allow for a complete mapping of the brain functions. With the biology of spatial recognition established, the attention will focus on matching neurological patterns with specific features.

More specifically to the current subject, future research should consider the connection between perception such as including visual information, proprioception, and cognition in the context of spatial representation.