Friday, October 8, 2010

Samir Zeki's laws of the visual brain

Memory (1896). Olin Warner (completed by Herbe...
Samir Zeki's laws of the visual brain:
  1. Constancy:  Despite the changes that occur when processing visual stimuli (distance, viewing angle, illumination, etc.), the brain has the unique ability to retain knowledge of constant and essential properties of an object and discard irrelevant dynamic properties.    Similarly, a work of art does likewise.   Forms do not have an existence without a brain and the capacity for stored memory. 
  2. Abstraction:  Abstraction is the the hierarchical coordination where a general representation can be applied to many particulars, allowing the brain to efficiently process visual stimuli.  Art externalizes the practices of abstraction in the brain
Ramachandran proposes a series of heuristics that artists use consciously or unconsciously utilize to optimally stimulate the visual ares of the brain:
  1. Peak Shift Principle:  In Peak Shift training,  animals respond better to exaggerated versions of the training stimuli.  Artists try to capture the essence of something to evoke a direct emotional response through  exaggerating such elements as shading, highlights, illumination, etc. 
  2. Isolation:  Isolating a single visual cue helps an animal direct its attention to allow itself to respond to a peak shift.  There is a need to isolate the desired visual form before that aspect is amplified.  This is why a sketch sometimes maybe more effective than a photograph, ie as in a cartoon. As Paul Klee said, "Art does not represent the visual world, it makes things visible." and one way to do this is to isolate a key feature.   On a neurological level,  the different enhancements to physical objects that intensify the pleasure of viewing result in the amplification of limbic system (the center of emotions in the brain) activation and reinforcement.
  3. Grouping:  Various means of grouping objects are used to delineate objects from the background.  Some of the techniques that we use in observing objects may have been genetically programmed from our early days when we had to be able to distinguish predators from a busy background, especially when a predator uses camouflage.  This occurs most efficiently when limbic reinforcement is fed back to early vision at every stage of visual processing leading up to the discovery of the object.   Constant emotional feedback helps the information discovery at each stage of a clue.
  4. Contrast:    Contrast is another means of eliminating clutter and focusing attention.The visual cortex is wired predominantly to step changes in luminance rather than homogeneous surface colors. Regions of contrast are information rich requiring reinforcement and the allocation of attention.  Unlike grouping, contrasting features are typically close eliminating the need to link distant, but similar features.
  5. Perceptual Problem Solving:  The discovery of an object after a struggle is more pleasing than one that is obvious.  An implied meaning often gives more pleasure than an explicit statement.
  6. Generic Viewpoint:  The brain dislikes viewpoints that  rely on a single vantage point.  Often times, it likes a sense of play.
  7. Visual Metaphor:  Grasping an analogy is rewarding.  The brain likes a surprise when two very dissimilar objects have a hidden, deeper connection. 
  8. Symmetry:  Symmetry complements the other principles relating to information rich material.  In nature,  detection of a predator, location of prey, and the choosing of a mate  are important uses of symmetry. 
Emotions play a big part in aesthetics and, not surprisingly, those areas in the brain are implicated in processing visual information as well.  In addition to processing visual information, the insula cortex is directly implicated in the sense of oneself, i.e., bodily self-awareness, sense of agency and sense body ownership.  In regard to emotion, the insula cortex is the seat for processing emotionally relevant context for sensory experience.   Interestingly enough, the insula also controls a number of motor skills which has led Ramachandran to call for an experiment measuring galvanic skin response to a piece of art.  He would like to see what our innate response is unmediated by voice response in that the two can be very different.
Not surprisingly, there is also a difference in our response to representational art (art that looks like a real object) and abstract art



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