Final answer:
Proximal stimuli are the sensory inputs directly interacting with our sensory receptors, while distal stimuli are the actual objects or events in the environment that supply the proximal stimuli. The light striking the retina is a proximal stimulus, while the object emitting the light is a distal stimulus. In two-point discrimination tests, fingertips have a closer caliper point distance due to higher receptor density.
Step-by-step explanation:
The difference between proximal stimuli and distal stimuli lies in their relation to sensory perception. Proximal stimuli are the patterns of stimuli from objects and events that reach your senses (eyes, ears, skin, etc.). For example, the light that strikes your retina is the proximal stimulus for vision. On the other hand, distal stimuli are the actual objects or events in the environment that you perceive and that provide information to the proximal stimuli. An example of a distal stimulus would be the actual computer screen from which emitted light reaches your eyes, making it the proximal stimulus.
To illustrate, in terms of tactile perception, the contact of a tuning fork or cotton tip applicator on the skin can be considered as proximal stimuli. The tuning fork and applicator themselves, which exist in the environment and cause the sensations upon contact, are the distal stimuli.
When testing sensory perception like two-point discrimination, the increased sensitivity and closeness of caliper points on the fingertips compared to the palm is due to a higher concentration of sensory receptors in the fingertips. Similarly, we would expect a greater distance between caliper points necessary for two-point discrimination on less sensitive areas like the arm or shoulder.