Answer:
perceptual set
Explanation:
Perceptual set -
It is the mental phenomena , where the person perceive certain things in a specific manner , is known as perceptual set.
In this method , the person ignores certain facts , during considering a particular task.
Hence, from the given scenario of the question ,
Alyosha perceive the normal pain and aches as the infectious disease, hence the correct term is perceptual set.