Today is a continuation of the first post.

A Thesis of Figure Ground Rhythm, Jamie Hahn, copyright 2010.

Chapter 1, section 2

“Movement seems to engage intimately with time…….The snow flakes within the landscape presents a seemingly still body and a rhythmic exchange between the senses reacting to the atmospheric changes. The result is a direct response of experience. Visual and tangible perception are keyed into a rather quick reactionary cognitive explanation of where the body is in relationship to other objects in space. Such direct attentiveness to the surrounding environment offers an opportunity to see more slowly. When the snowflake landed on your nose, you were still, calm, and focused. Within the furry of a million flakes fluttering around your stance, one became the object of study. The calm and focus occurred between the stillness of the flake at rest and the stillness of your stance, and then, your ability to see movement slow and pause. Time seemed to slow down. The flake changed pace, slowed in tempo, rested and paused before floating on to its final destination. In that time, that slow time, seeing motion gradually allowed a beautiful exchange to take place. This is exchange is what I like to call figure ground rhythm.

To introduce this concept, a conversation on what perception is needs to occur. Defining perception is something of a task. Perception involves the senses and is always working as we are always sensing surrounding stimuli. From the visual to the tactile, the senses keenly tune into an immediate interpretation of what is being perceived. From that percept, follows cognition or making sense, gaining understanding or acquiring knowledge. Defining perception in the dictionary finds eight notes of meaning; each slightly different from the other, although all pertaining to sameness. The intricate differences are interesting to compare and learn from as they contribute significantly to seeing and understanding. A few are listed here:

1. the act of apprehending by means of the senses, understanding

2. intuitive appreciation, insight, discernment, the result of perceiving

3. interpretation of sensory stimuli based on memory

In seeing there is learning. What is new is welcomed by what is known, memory meets discovery. All visual variables contribute: value of lightness, depth of field or spatial view, line, shape, texture and motion. And, all tactile variables contribute: sense of touch and balance as in kinesthetics and proprioception where the body moves in awareness of itself moving through space. Physiologically, perception is cognitive understanding of information gained by the senses. And, while a natural occurrence, is perhaps taken for granted in everyday experiences. Not often is it discussed in interactions with snowflakes. However, perception is vital in influencing everything from memory, to place, and orientation, to identity.

In a kind of rhythmic dance, the body relates and reacts to stimuli within a given environment. To grasp an understanding of perception, an investigation into how visual sense data is processed needs to be reviewed. Vision, or eyesight as science knows it today, involves research in psychology, cognitive science, neuroscience and biology. “When the eye assimilates information from the environment, the lens of the eye focuses an image onto a light-sensitive membrane at the back of the eye. The retina converts patterns of light into neuronal signals while the lens focuses light on the photo receptive cells of the retina, which detect the photons of light and respond by producing neural signals. The signals are processed in a hierarchical fashion by different parts of the brain.” While this explanation covers part of the ‘how’, what is still needed is the other ‘how’. This is how what is seen becomes known as a familiar object. Perceptual knowledge is also formed from memory, context and recognition. Perception involves thinking and reacting. Lines connect and form shapes. The circular object on the wall becomes a clock. A rectangular shape becomes a picture frame. Whatever may be in a line of vision is seen as what it is or is figured out based on context.

In psychology, one such explanation of perception stems from Gestaltism which formed out of the Berlin School in the early twentieth century. The theory “refers to the form-forming capability of our senses, particularly with respect to the visual recognition of figures and whole forms instead of just a collection of simple lines and curves”. By trying to define or explain how objects were being perceived, Gestalt psychology formed laws and principles. Later in the twentieth century, as science and psychology evolved, Gestalt was criticized for being merely descriptive; however, the ideas helped further research into the “perception of patterns and objects in relation to behavior, thinking and problem solving”.

The principles of Gestalt systems come in the forms of: emergence, reification, multistability and invariance. Samples of emergence show a scene of directional shapes made up of black spots against a white ground. The rhythm or variance of location of the spots lead the eye to see the whole first and then, see the parts. Reification is a construction of perception also from such spots and how they are arranged in a directional pattern. The spatiality of a shape is formed between the positive and negative spaces to convey a suggested contour shape. In multistability, ambiguous shapes shift back and forth from a positive to negative outlining two or more possible objects. This figure ground relationship is most well known in the vase/figure/face illusion where the shape contrasts with figurative lines. Finally, invariance is ‘simple geometrical objects being recognized independent of rotation, translation and scale’ in various directions including different shades, textures and lighting.

In addition to Gestalt principles, the laws were designed to explain visual perception as an experience of sensation which lead to the interpretation of such. Closure, similarity, proximity, symmetry, continuity, and common fate are defined here:

1. Closure: the mind may experience elements it does not perceive through sensation in order to complete a regular figure
2. Similarity: the mind groups similar elements into collective entities or totalities. Similarity might depend on form, color, size or brightness.
3. Proximity: spatial or temporal proximity of elements may indue the mind to perceive a collective or totality
4. Symmetry: figure ground relationships in symmetrical images are perceived collectively, even in spite of distance
5. Continuity: the mind continues visual, auditory and kinetic patterns.
6. Common Fate: elements with the same moving direction are perceived as a collective or unit.

Colliding with visual data input to the retina is the constancy of motion and depth. Each contribute simultaneously with the cognition of what is being seen and interpreted. When elements within a scene are moving, both speed and direction are processed. Studied in neurology, engineering and psychology, motion perception is outlined in two orders. The first order examines the process of figure ground when the motion of an object differs in lightness from its background. One example is a black bug walking from one side of the wall to the other. A simple motion detected by a simple sensor in the retina. The second order of motion is when a moving shape is ‘defined by contrast, texture, flicker or some other quality that does not result in an increase in luminance  or motion energy’. This order is considered a weaker ‘temporal resolution’ of the moving stimuli. When integrated, the visual system can detect various parts within a two dimensional field of view and differentiate this view from a ‘global’ or three dimensional representation of moving surfaces and objects.

The ability to see three dimensionally is derived from depth perception. Right alongside is the sensation of depth, which allows the body to move and respond to an environment based on the distances between objects in spatial relationship to the body. Each perception involves visual clues from both eyes and input from just one. Binocular vision is more about depth and stereopsis while monocular is on size and objects at different distances appearing smaller or larger depending on location and comparison. Both types of vision contribute to how depth is perceived in what is called motion parallax. The body in motion changes or alters the view of stationary objects within a scene. This shift in background to object helps to give cognitive cues as to the relative distance between the object and the observer. In physics, “if the information is known about the direction and the velocity of movement, motion parallax can provide absolute depth information”. One example of this is when driving in a car, objects closest appear to not move at all, they seem smaller and less detailed. When driving, our visual percept of motion heightens our sense of kinetic depth perception. Objects that appear to be changing in size; bigger for instance, begin to feel closer. The brain uses kinetic depth perception to sense reaction time known as TTC “time to contact” depending on velocity and allows our visual information to guide away from a possible collision with the enlarged and too close object.

A balancing act occurs when motion between the close objects and the distant objects relate to the figure (the body) in space thus becoming a multi-dimensional figure ground percept. In time, as motion and movement cause reaction per perception of view and of detailed focus, a rhythmic exchange occurs between the figure and the ground. In the concept of figure ground rhythm, the figure is the body as it moves in reaction to and in relationship to the ground which is the environment, therein. Rhythm is based on time as it shifts from moment to moment, viewpoint to viewpoint. Joining this dance of perceptual interaction is a key element related to time: light.

Chapter 2 will begin with the next post.

References: The Physiology of Perception, Walter Freeman, University of California, 1991