CHAPTER 1 1Sensory Perception
We experience sight, sound, smell, taste, temperature, the feel of the
wind on our face. In all these cases, the brain receives signal infor-
mation from the environs of the body and uses that information to
form a mental experience of the world. This process is called sensory
perception and constitutes an important nexus between brain, mind,
and behavior. Sensory perception may be divided into two basic com-
ponents: (1) the collection of information from the environment via
sensory organs and receptors and (2) the analysis and interpretation
of this information by the nervous system, contributing to the experi-
ence of mental states of perceptual awareness. Sometimes component
1 is called sensation and component 2 perception.
Even very simple organisms have sensation. Single-celled bacteria
detect and respond to physical stimuli in their environment. For ex-
ample, the bacteria Escherichia coli and Salmonella respond to the pres-
ence of chemical substances present in the soupy medium through
which they move. How do they do this?
These bacteria swim in a series of maneuvers called runs and tum-
bles. A bacterial cell swims in a straight line for a second or so (a run)
and then stops swimming and flops around for a moment (a tumble);