The Human Visual System

Description how the visual system works

The human visual system is a process that begins with the retina, receptor cells and includes two kinds of photoreceptors called cones and rods, the optic nerve (Breedlove and Watson, 2013). The retina is in the back of the eye and contains several cells in separate layers. The retina is the ‘receptive surface’ that allows the light to enter and contains photoreceptors. There are two kinds of photoreceptors called rods and cones that perform their own distinct function. They release neurotransmitter molecules, (Breedlove & Watson, 2013) which control the bipolar cells that synapse with the rods and cones. Bipolar cells connect to ganglion cells and their axons then form the optic nerve. The optic nerve carries information to the cerebral cortex in the brain, and this, results in visual perception.

How context can affect the visual perception

 Todorovic (2006) used a very clear example of visual field and visual target to how context affects the visual perception. According to him visual field is all that is around the eye or what the eyes can see; however, there are some objects that catch the visual attention, and this is due to the context in which those objects are perceived. His study explained this context of visual perception on geometrical basis as well.

Two potential benefits of context affecting visual perception

One major benefit of context is ‘recognition’ and to focus of what seems familiar to the eye in the complex settings the visual system is viewing (Chun, 2000). Visual memories are based on putting what you see in the present in the context when you saw the same person, event or thing in the past.

The reflex action is a spontaneous response of the body to any stimuli, possibly with danger (American Psychological Association, APA). Reflex action as a result of visual perception is possible if the is perceived in its context. An example is that if a knife lying on the counter seems harmless with no reflex stimulated, but the same knife if held by an attacker will get a different reflex.

Two potential costs of context affecting visual perception

A cost of context affecting visual perception would be the opposite of the benefit mentioned above i.e. the recognizing factor. If there is no recognition then memory of what is perceived by the eye is lost and a good example of patients suffering from amnesia. They are able to visually perceive and their visual system is normally functioning, however, what is missing is the context of what they have already seen in the past.

Another cost would be misunderstanding or ove looking what the reality is of what the eye is looking at. If there is a huge crowd and a person is looking for a single person, then context can keep him distracted from that one person who is looking for.

Chun, M. M. (2000). Contextual cueing of visual attention. Trends in Cognitive Sciences, 4(5), 170-178.

Todorović, D. (2006). Geometrical basis of perception of gaze direction. Vision research, 46(21), 3549-3562.