用户:Grotton JXz Donbrako/Psychology/Chapter 4

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• Sensation refers to the process of sensing our environment through touch, taste, sight, sound, and smell.  
• Perception is the way we interpret these signals or sensations and make sense of everything around us.

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Sensation

• Our senses: receptors in our eyes, skin, tongue, nose, receive stimuli from our environment.
• What is a stimulus?
  • Energy transmitted from the environment (e.g., light, chemicals, pressure, heat).
• Transduction: Stimuli from the environment are transformed into neural impulses.

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• Sensory adaptation is a decreasing responsiveness to stimuli due to constant stimulation (e.g., when standing in a noisy environment).
• Sensory habituation: Our perception of sensations is partially due to how focused we are on them.
• Cocktail Party Effect: Your ability to block out a lot of irrelevant stimuli in your environment.

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Sensation: VISION

• Visible light is a small section of the electromagnetic spectrum

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• Objects appear the color they do as a result of the wavelengths of light they reflect.
  • A red shirt reflects red light and absorbs all other wavelengths.
  • An object appears black because it absorbs all wavelengths.
  • A object appears white because it reflects all wavelengths.

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• The Cornea: Controls the light coming from the outside and focuses it onto the pupil.
• The Pupil: Is a hole located in the center of the iris of the eye that allows light to strike the retina.
• The Retina Is where the actual processing of the light occurs and is translated by rods and cones.
• The Fovea: A small depression in the retina where visual acuity is highest.
  • The center of the field of vision is focused in this region, where retinal cones are particularly concentrated.

• Light enters the eye through the cornea.
• Light passes through the pupil.
• The lens focuses the light onto the retina.
• Light energy is converted into neural energy.

• Rods and Cones are photoreceptors in the human retina.
  • Cones are activated by color.
  • Rods are activated by white light and the absence of light.
  • If rods and/or cones are stimulated by light, then they transmit this information to a second layer of cells called bipolar cells.
• Bipolar cells send this information to a layer of cells called ganglion cells.
• Ganglion cells make up our optic nerve which sends the information to the thalamus in our brain.

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Eyes to the brain

• The signal, travelling along the optic nerve, is transmitted to the Lateral Geniculate Nucleus.
• Lateral geniculate nucleus;;; is a region of the thalamus.
• The lateral geniculate nucleus transmits the signal to the visual cortex in the occipital lobe.

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Theories of Colour Vision

• Trichromatic Theory: We have three types of cones in our retina, cones that detect blue, red, and green, and that different activation combinations of the cones produces all the colours we see.
• Trichromatic theory does not explain after images.

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• Opponent Process Theory: Sensory receptors arranged in the retina come in pairs: red/green, yellow/blue, black/white.
• If one sensor is stimulated, its pair is inhibited from firing.
  • If you stare at a red colour for awhile, you fatigue your sensors for red.
• Opponent process theory explains after images.

• Opponent processing theory also explains color blindness; if color sensors come in pairs, and an individual is missing one pair (e.g., red/green) then he or she should have difficulty seeing those colors.

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Sensation: HEARING

• Auditory sense uses energy in the form of sound waves instead of electromagnetic waves.
• Sound waves are created by vibrations which travel through the air and collected by our ears.

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• The process of hearing:
  1. Sound waves enter the outer ear.
  2. Sound waves cause the ear drum to vibrate.
  3. Three tiny bones, stapes, incus, and malleus, in the middle ear amplify the vibrations and send them to the inner ear.
  4. Vibrations hit the cochlea which is lined with hair cells; hair cells moves and trigger the release of neurotransmitters.
  5. Electrical signals sent by the auditory nerve travel to the brain.

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Theories of Hearing

• Place Theory: The hair cells in the cochlea respond to different frequencies of sound based on where they are located in the cochlea.
  • We sense pitch because the hair cells move in different places in the cochlea.

• Research demonstrates that place theory accurately describes how hair cells sense the upper range of pitches but not in the lower tones.

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• Frequency Theory: Lower tones are sensed by the rate at which hair cells fire.
  • We sense lower ranges of pitch because the hair cells fire at different frequencies in the cochlea.

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Sensation: SKIN

• Our skin has a set of nerves that detect temperature and pressure.
  • The amount of nerves in one area also varies;
    • your lips have many more nerves and can detect slight changes pressure or heat much easier than your lower back.

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Sensation: TASTE

• Certain nerves respond to chemical energy.
• Taste buds are located on the papillae, which are bumps on your tongue.
  • Some are also located on the roof of your mouth and cheeks.
• Types of tastes: sweet, salty, sour, bitter, savory.

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(待补充)

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