Explain how biological preparedness can be applied to taste aversions and phobias?
Evolution has made humans respond more negatively to certain neutral stimuli because of other stimuli that have been associated with them that may be dangerous or harmful.
Biological preparedness is the principle that certain negative associations are easier to make for the sake of survival of the species, based on human experience in the past.
An example is the snake. On its own as an object it is entirely harmless and would elicit no response from someone who has no experience of snakes, meaning it is a neutral stimulus. However, when a snake bites a human, it becomes a negative stimulus, and the human is conditioned to have a fear of snakes, because it has associated the object of a snake with the effects of its bite.
Through the course of human history it has become easier to associate the snake with its bite, and so some people may have innate fears or phobias of snakes for no apparent logical reason.
Taste aversions may come from the same principle. I have a friend who has problems with migraines, and once ate cheesecake and had a severe migraine afterwards. He loved cheesecake all through his childhood, but now has subconsciously associated it with migraines and gags at the thought of them. This is an example of classical conditioning, because a harmless thing has been associated with a harmful thing and so a conditioned response, such as screaming or gagging, is elicited by a harmless stimulus.
Classical conditioning was described in 1913 by John Broadus Watson, who famously said
"Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select - doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations and the race of his ancestors."
He believed that the entirety of human psychology can be explained by classical conditioning, which is a form of behaviourism, and is almost by definition reductive.