"Perhaps an emotional response requires physical stimuli," commented another of the boys.

Attention is the process by which a concentration is focused on a point of interest, such as an event or physical stimulus.

Receptor cells produce an electrical change in response to a physical stimulus.

Stevens' power law is a proposed relationship between the magnitude of a physical stimulus and the intensity or strength that people feel.

Light is the external physical stimulus of the retina's activity.

It responded not only to physical stimuli but to thoughts.

This is possible; there is reaction to local physical stimulus.

The simple procedure begins by asking whether the patient is able to move and react to physical stimuli.

Flow and focus become associated with these physical stimuli.

Peabody seemed to react only to physical stimuli, to threats of violence.