What does a higher threshold in photoreceptors indicate?

A higher threshold in photoreceptors indicates lower sensitivity. This means that the photoreceptors require a greater intensity of light to respond or for an action potential to be generated. In other words, when the threshold is high, the photoreceptors do not activate as readily in response to low levels of light.

This concept is fundamental in understanding how our visual system adjusts to different lighting conditions. For example, under bright light conditions, photoreceptors may exhibit a higher threshold because they become less sensitive to light to prevent overstimulation and potential damage. In contrast, a lower threshold signifies higher sensitivity, allowing the photoreceptors to respond to lower light levels.

Thus, recognizing that a higher threshold correlates with lower sensitivity helps clarify how photoreceptors function across varying lighting environments.