What is it?
Being able to process a visual stimuli is a seven step process. After seeing the stimuli, the light is reflected through the eye and onto the retina by the principle of transformation and representation (Goldstein, 2014). Next the visual receptors transform the light energy into electrical energy and shaping the perception by the visual pigments. The fourth step involves the neural processing which happens in neurons similar to the retina. The signals travel all the way to the brain. When the signals reach the brain, the visual stimuli is perceived, recognized, and deciding how to act on the stimuli. By perceiving the object, the brain gives it meaning and we are able to recognize it (Goldstein, 2014).
Gestalt theories state a person views the object as a whole and is able to take parts from the whole, but we see the whole object first (Goldstein, 2014). Humans perceive stimuli as a whole object instead of tiny points that make up an object like structuralism viewed perception. Gestalt approach has six different principles that make up the theory including proximity, similarity, common fate, good continuation, closure, and area/symmetry (Breedlove & Watson, 2013).
Here you can see the difference in the cornea between a normal and astigmatic eye. The normal vision eye is shaped like a basketball while the eye with astigmatism is shaped oblong like a football. This is what causes the light to bend in different ways causing the vision to be off. (Rutherford, 2016).
This picture shows what happens when light enters through the cornea and hits the point of focus. With astigmatism, the point of focus is hit but there are other areas being stimulated as well. A normal eye will focus right on the retina is one spot and the image will be clear. (Rutherford, 2016).
The vision with astigmatism is very blurry. As you can see the picture on the right is what stimuli looks like when you have an uncorrected astigmatism. The picture on the left is normal vision. Since the light is focusing on more than one spot, the stimuli is presented as blurry. (Flores, 2014)
Breedlove, M. & Watson, N. (2013). Biological psychology: An introduction to behavioral, cognitive, and clinical neuroscience (7th Ed.). Sunderland, MA: Sunderland Associates, Inc.
Goldstein, E.B., (2014). Sensation and perception. (9th Ed.) Belmont CA: Wadsworth
Helwig, D. L. (2013). Astigmatism. In B. Narins (Ed.), The Gale Encyclopedia of Nursing and Allied Health (3rd ed., Vol. 1, pp. 350-352). Detroit: Gale. Retrieved from GVRL database.
Flores Eye Clinic [Photograph]. (2014). Retrieved from http://floreseyeclinic.com/education/3023-astigmatism.html
Rutherford Eye Care [Photograph]. (2016). Retrieved from http://www.rutherfordeyecare.com/your-eyes/astigmatism/