Sensation And Perception

5 Pages 1248 Words

Sensation and Perception
Interactive Lectures


Sensation is the detection and direct experience of physical energy as a result of environmental or internal events. Perception is the process by which sensory impulses are organized and interpreted.


Our Sensational Senses


Sensation begins with the sense receptors, which convert the energy of a stimulus into electrical impulses that travel along nerves to the brain. Separate sensations can be accounted for by anatomical codes (as set forth by the doctrine of specific nerve energies) and functional codes in the nervous system. In a rare condition called synaesthesia, sensation in one modality evokes a sensation in another modality, but these experiences are the exception, not the rule.

Psychologists specializing in psychophysics have studied sensory sensitivity by measuring absolute and difference thresholds. Signal-detection theory, however, holds that responses in a detection task consist of both a sensory process and a decision process and will vary with the person’s motivation, alertness, and expectations.

Our senses are designed to respond to change and contrast in the environment. When stimulation is unchanging, sensory adaptation occurs. Too little stimulation can cause sensory deprivation. Too much stimulation can cause sensory overload, which is why we exercise selective attention.
Vision


Vision is affected by the wavelength, frequency, and complexity of light, which produce the psychological dimensions of visual experience—hue, brightness, and saturation. The visual receptors—rods and cones—are located in the retina of the eye, and send signals (via other cells) to the ganglion cells and ultimately to the optic nerve, which carries visual information to the brain. Rods are responsible for vision in dim light; cones are responsible for colour vision. Dark adaptation occurs in two stages.
The Structures of the Retina



Click here to view t...