Final answer:
This is an example of a perceptual barrier. The flickering lights in the classroom hinder Alex from concentrating on the professor's lecture.
Step-by-step explanation:
This is an example of a perceptual barrier. Perceptual barriers refer to factors that hinder one's ability to perceive or interpret sensory information accurately.
In the given scenario, the flickering lights in the classroom are causing Alex's inability to concentrate on the professor's lecture. The constant changes in lighting conditions due to the flickering lights create a distracting and disruptive environment that interferes with Alex's perception of the lecture.
Perceptual barriers can also include other factors such as loud noises, strong odors, or discomfort from physical sensations that impede one's ability to focus and comprehend information.