Which of the following best exemplifies sensory adaptation?

The concept of sensory adaptation refers to the process by which receptors become less responsive to constant stimuli over time. This adaptive mechanism allows individuals to become less aware of unchanging stimuli, enabling them to focus on more relevant changes in their environment.

In the context of the first choice, noticing a faint smell in a room after being there for a while exemplifies sensory adaptation perfectly. Initially, when entering the space, a person may be acutely aware of the odor. However, as time passes and the sensory receptors for that smell become accustomed to its presence, the individual may stop perceiving it as intensely. This diminished perception despite the continued presence of the stimulus illustrates the essence of sensory adaptation.

The other scenarios given do not represent sensory adaptation effectively. In the second choice, feeling the weight of a backpack immediately after putting it on highlights initial sensory perception rather than adaptation; the weight is a new stimulus. The third option, reacting to a sudden noise in a quiet room, showcases a noticeable change in the environment, triggering a response rather than a decrease in awareness over time. Lastly, the fourth scenario of a friend tapping on the shoulder during a conversation indicates an immediate distraction and sensory engagement rather than the gradual decline of sensory perception associated with adaptation.