Final answer:
The 'fear of the unknown' is a learned emotion often resulting from a generalization of past experiences, as illustrated by psychological theories such as stimulus generalization in classical conditioning and the concept of xenophobia.
Step-by-step explanation:
The phrase "fear of the unknown" is usually a learned emotion, based on a generalization of past experiences. This concept is supported by the behavioral psychology theory of classical conditioning where an organism learns to associate stimuli and generalize their response to similar stimuli. A classic example is Watson and Rayner's experiments with Little Albert, who was conditioned to fear a white rat and then began to fear other furry white objects, an instance of stimulus generalization.
Furthermore, the irrational fear or hatred of another culture, known as xenophobia, can also be thought of as a learned emotional response, often stemming from a lack of critical thought or exposure to negative stereotypes. These concepts illustrate how experiences can shape our emotional reactions to new or unknown situations through generalization, a hasty generalization, or social learning.