1. Sensation and Perception Chapter 4

2. Sensation - the stimulation of sensory receptors and the transmission of sensory information to the central nervous system.

3. Sensory receptors are located in sensory organs like the eyes and ears.
Perception - the psychological process through which we interpret sensory stimulation.

4. Absolute Threshold - the weakest amount of a stimulus that can be sensed. (Ex: a hearing test, the faintest beep you can hear) This is different for everyone. Very different in animals.

5. Difference Threshold - the minimum amount of difference that can be detected between two stimuli. (Ex: the difference between to very similar paint chips)

6. Signal-Detection Theory - a method of distinguishing sensory stimuli that takes into account not only their strengths but also such elements as the setting, your physical state, mood etc.

7. (Ex: your food has little taste when you have a head cold)

8. Sensory Adaptation - the process by which we become more sensitive to weak stimuli and less sensitive to unchanging stimuli. (Ex: eyes adapting to darkness, getting used to certain sounds)

9. The Eye
Pupil - opening in the eye that lets in light. The darker it is the more the pupil opens to let in more light.
Lens - adjusts to the distance of objects by changing its thickness.

10. Retina - sensitive surface that acts like film in a camera.
Neurons in the eye that are sensitive to light are called photoreceptors. Nerves carry visual input to the brain.

11. Blind Spot - part of the eye where the optic nerve leaves the eye
Blind Spot - part of the eye where the optic nerve leaves the eye. There are no photoreceptors.
Rods - photoreceptor that allows us to see black and white

12. Cones - photoreceptor that allows us to see color.
Visual Acuity - sharpness of vision, ability to see details.
Nearsighted and farsighted

13. The Ear
Outer Ear, Middle Ear and Inner Ear
Inner Ear
Cochlea -tube that contains neurons and fluids

14. Auditory nerve - transmits neural impulses to the brain
Deafness - about 2 million Americans are deaf
inherited, disease related, injury related or old age.

15. Conductive Deafness - occurs because of damage to the middle ear
Sensorineural Deafness - occurs because of damage to the inner ear.

16. Other Senses
Smell
Olfactory Nerve - sends info about odors to the brain
Taste - As you get older you may lose your sense of smell which takes away from taste.

17. Skin Senses (Touch)
Pressure, Temperature, Pain
Gate Theory - only a certain amount of info can be processed by the nervous system at a time.

18. This is why if you rub an injury it makes it feel better because the messages are competing for the brain’s attention. The pain message may not be getting to the brain.

19. Many people experience pain in a limb that is no longer there
Many people experience pain in a limb that is no longer there. More than 1/2 of veterans with amputated limbs report feeling pain.

20. Body Senses
Vestibular Sense - tells you whether you are physically upright without having to use your eyes.

21. Kinesthesis - the sense that informs people about the position and motion of their bodies.