blog #8

Optical illusions have always been a strange wonder to many.  An optical illusion, is an illusion caused by the visual system and are identified by visually perceived images that are different from objective reality. There are three main types of illusions: literal optical, that create images that are different from the objects that make them, physiological illusions that are the effects of extra stimulation of a specific type (brightness, color, size), and cognitive illusions, the result of unconscious inferences. Pathological visual illusions are created from a pathological exaggeration in physiological visual perception mechanisms causing these types of illusions.

One of the most important tools used by neuroscientists to understand how the brain creates its sense of reality is the visual illusion. Historically, artists as well as researchers have used illusions to gain insights into the workings of the visual system. Before scientists were studying neurons, artists had created a series of techniques to trick the brain into thinking that a flat canvas was three-dimensional or that a series of brushstrokes was a still life. Visual illusions demonstrate the ways in which the brain can fail to re-create the physical world. M. C. Escher, Dalí and Duchamp are all successful artists who play with optical illusions. Although observing optical illusions is amusing, understanding how and why we look at them the way they are is just as fascinating.

Gestalt psychologists think that one way optical illusions are done is by looking into individual sensory stimuli as a whole. Gestalt organization can be used to explain many illusions. Gestalt psychology is a philosophy of mind of the Berlin School of experimental psychology. It is an attempt to understand the laws behind the ability to have and maintain meaningful perceptions in an apparently “chaotic world.” The Gestalt principles of perception govern the way we group different objects. Good form is where the perceptual system tries to fill in the blanks in order to see simple objects rather than complex objects. Continuity is where the perceptual system tries to come up with which pieces fit together into continuous lines. Proximity is where objects that are close together are linked. Similarity is where objects that are similar are seen as related.

Perception is the organization, identification, and interpretation of sensory information in order to understand information that is presented, or the environment. All perception involves signals that go through the nervous system, which can result from physical or chemical stimulation of the sensory system. Perception depends on complex functions of the nervous system, but seems mostly effortless because this processing happens outside conscious awareness. The process of perception starts with an object in the real world, called the distal stimulus or distal object. By means of light, sound or another physical process, the object triggers the body's sensory organs. These sensory organs transform the input energy into neural activity by a process called transduction. This pattern of neural activity is called the proximal stimulus. These neural signals are then sent to the brain and processed. The resulting mental re-creation of the distal stimulus is the percept.