Lecture 4: Sensation and Perception
• Sensation: process by which we bring in external energy sources into out CNS
• Perception: making sense of the external energy sources brought in through
A 13 C
**The middle characters can either be perceived as 13 or a capital B.**
Sensation; physical sensing of environment physiological process relatively
objective learning/experience not required i.e.: chalk on a board
Perception; mental interpretation of environment psychological process relatively
subjective dependant on learning/experience i.e.: words on a board
Transduction: translation of external info into neurotal language.
• Vision; electrical:
o stimulus energy; light waves
o sensory receptors; photo-sensitive rods and cones in retina
o sensory transduction; photoreceptors optic nerve thalamus visual
cortex of occipital lobes
• Audition; electrical:
o stimulus energy; sound waves
o sensory receptors; pressure sensitive hair cells in cochlea of inner ear
o sensory transduction; tympanic membrane ossicles cochlea
basilar membrane auditory nerve thalamus auditory cortex of
• Olfaction (smell); chemical:
o stimulus energy; shape of molecules in inhaled air
o sensory receptors; mucous membrane of nose
o sensory transduction; mucous membrane olfactory nerve limbic
• Gustation (taste); chemical:
o stimulus energy; shape of molecules dissolved in saliva
o sensory receptors; tongue
o sensory transduction; taste cells in taste buds facial nerve thalamus
taste receptors throughout brain
• Tactile; chemical:
o stimulus energy; touch, temperature, pain o sensory receptors; sensory neurons in skin
o sensory transduction; skin receptors trigeminal nerve (above neck) or
spinal nerves (everywhere else) thalamus somatosensory cortex of
• Kinaesthetic; internal environment:
o stimulus energy; pressure strain
o sensory receptors; joints, muscles, tendons
o sensory transduction; sensory neurons spinal nerves cerebellum
• Vestibular; internal environment:
o stimulus energy; motion
o sensory receptors; inner ear
o sensory transduction; semicircular canals cerebellum
Extrasensory perception: perception without sensation.
- Precognition; having cognitive knowledge of something before it happens.
- Clairvoyance; experiencing something that is happening, but not within your
- Telepathy; the ability to speak to one another without exchanging any known
- Psychokinesis; the ability to move objects without touching them. Not truly
** The coin game Lecture 4 (part 2): States of Consciousness; Sleep and Dreams
Sleep at one point was dismissed as “not awake”. This theory changed in
the 1950’s when people began to observe that sleep had a lot of activity involved in it.
When we became able to monitor our bodies through technology, sleep was observed and
was discovered to be incredible.
- Physical reaction when going to sleep; heart rate slows, breathing irregulates,
muscles relax, “hypnic jerk”, “myoclonic kick. Vision, auditory, then all
other senses disconnect (though never entirely); RAS [pilot light] will bring
you back to a state of awakeness when you perceive something around you
(i.e.: crying baby, smoke alarm, etc).
- Neurological reaction when going to sleep; electrical voltage increase.
- Psychological reaction when going to sleep; as the environment slips from
awareness, so does the ability to keep track of time. Even if you have
insomnia, your sense of time will be disturbed. The ability to direct thoughts
lessens. “Hypnagogic hallucinations” (feelings/thoughts felt prior to falling
asleep, red is a dominant color, produces a sense of falling/stepping into
- Finally, you move into sleep.
• Sleep is restorative, and has evolved as a survival mechanism. Sleep is
a safe place to disconnect from the world and to save energy.
• Caloric intake vs. amount of sleep / size of animal vs. amount of sleep
Small animals who eat a lot in a small amount of time tend to
sleep a lot
Large animals who eat a lot over a long period of time tend to
o Awake/relaxed brain waves are very similar to the begi