Perception Case

1. Describe how light reflects off a surface. What are some terms a jury should know?

Light travels in a straight path until it strikes something in which the light can either bend, bounce back, be absorbed or polarized. Reflection occurs when light bends and bounces back to meet our eyes. Reflection is the reason we are able to see objects because objects are only seen by the light that they reflect. Incoming light waves are known as the incident wave while the wave that is bounced back to meet our eyes is known as reflected wave. Reflected light follows the law of reflection that states that the angle of incident wave is equal to the angle of reflected wave for light to be bounced back and for reflection to occur.

Reflection off of smooth surfaces leads to light traveling in one direction and reflected off in one direction, which is known as specular reflection. Reflection off of rough surfaces such as rough roads leads to light being reflected in various directions, which is known as diffused reflection.

Light behaves as both a wave and as if it was composted of particles. According to the wave-based theory, light spreads out in all directions. According to the particle theory, when photons are absorbed they are put into an excited state then to a relaxed state where they emit a photon with equal energy of the original photon which can go in various directions, causing diffuse reflection. For specular reflection, photons are not absorbed and re-radiated, they are simply bounced back.

The objects we see everyday such as people, cars, animals, flowers, trees etc do not emit visible light by themselves. These objects reflect incident sunlight and artificial light.

2. Describe Perception Reaction Time. What is this and what should a jury know?

Perception reaction time is the time between a stimuli being presented and the response initiation made by the driver. An example of this would be the time it takes for a driver to detect a cat on the road and decide to apply the breaks. Perception reaction time occurs in four sub stages of mental processing time. The fist step is sensation, the time that it takes for the driver to detect something is present in their field of vision. Perception/ Recognition follows, which is the time to interpret the meaning of the sensory input. Situational awareness, the third step, is the time in which the driver realizes the situation of the scene and what needs to be done. Lastly is the response selection and programming step, which is the time necessary for a driver to make a move of action. These four steps make the total perception reaction time. The average perception time for a human is .75 seconds and the average reaction time is .75 making the average perception reaction time to be 1.5 seconds. Low visibility, neurological disorders, alertness and uncertainty can produce longer perception reaction time, which