Summary of Difficult Terms
Light is reflected from surfaces of all the items, and that reflected light is collected by the eye. The light enters the eye through the lens that focuses the light on the back of the eyeball. The pictorial nature of the image is then converted into electrical signals that the eye sends to brain where the signals are interpreted. Lens contracts and expands in absence and presence of light to adjust the light that enters the eye.
How the Ear Hears:
When something vibrates, it displaces the air and makes waves in it. These waves make their way into the ear and after passing through the ear canal, they strike on the ear drum. The ear drum passes the vibration on through bones to the inner part where signals of vibration are sent to the brain for interpreting the sound waves. The brain interprets what the sound means.
A psychoactive drug is a chemical substance that has a biological/ chemical effect on the nervous system and changes the state of brain and its functions resulting in the alteration of mood, perception and level of consciousness of the user. These drugs have the influence of mental health instead of physical health.
Pavlov’s Classical Conditioning:
Pavlov found through experimentation that organisms learn the potential effect of stimulus that is not part of their naturally existing set of stimuli but is related to one. For example smell of food stimulates the body about the coming food, but if an irrelevant stimulus is introduced before provision of food (i.e. sound of tuning fork in case of Pavlov’s experiment) then that irrelevant stimulus becomes a relevant stimulus. When tuning fork was sound, it stimulated the taste buds.