Transduction is best defined as:

Transduction is accurately defined as the process of converting physical energy into neural signals. In the context of sensory perception, this means that when our sensory organs detect physical stimuli—such as light waves, sound waves, temperature changes, or chemical substances—transduction occurs as these stimuli are transformed into electrical signals that can be processed by the nervous system.

This is a fundamental aspect of how we perceive the world around us; without transduction, our brains would not receive the necessary information from our environment to interpret various sensations. For instance, in vision, light enters the eye and is converted into neural signals by photoreceptors in the retina before being sent to the brain for interpretation.

The other options provide related concepts but do not accurately characterize transduction. The alteration of stimulus intensity in perception refers more to the way we perceive changes in stimuli rather than their conversion. The adaptation of sensory receptors refers to how they become less responsive to constant stimuli over time, rather than the initial conversion step involved in transduction. Lastly, the relationship between sensation and cognition pertains to the broader process of how we think about the information we receive, which is distinct from the physical act of converting stimuli into signals.