When people are presented with a stimulus, the brain processes the information in two pathways. The "fast" pathway goes from the thalamus directly to the .

When people are presented with a stimulus, the brain processes the information in two pathways. The "fast" pathway goes from the thalamus directly to the Amygdala.

Explanation:

Amygdala is the part of the emotional brain which is associated with the perception of fear, sadness, anger and agression.

Amygdala also plays a role in sexual  activity and libido. The  size of amygdala greatly reflects the rate of functional activity of the amygdala.

When the perception of stimulus follows fast pathway then the information travels directly from thalamus to amygdala and if it follows a slow pathway then the information passes from thalamus to cortex and then to the amygdala.

the index of refraction of the second medium is higher. i just took the test trust me !