Sensation and Perception

Sensation and Perception

Sensation • The process of taking in information from the environment

Perception • How we recognize, interpret, and organize our sensations

Input comes from the five senses: • Visual (Eyes) • Audio (Ears) • Cutaneous/Tactile (Touch) • Olfaction (Smell) (Nose) • Gustation (Taste) (Tongue)

Receptor Cells • Each of the five senses is specifically coded to only take in one type of stimulus, whether it be light waves, sound waves, smell, taste, or touch.

Receptive Field • The area from which receptor cells receive input (audio from ears, visual from eyes, touch from the skin, taste from the tongue, smell from the nose)

Transduction • Changing sensory input into an electrochemical message, from the sense receptors to the brain, and the brain to the correct area for action.

Contralateral Shift • When information travels from one side of the body to the opposite side of the brain for interpretation.

Kinesthetic Sense • The system for sensing the position and movement of individual body parts. • Receptor cells located throughout the muscles and joints of the body. • A common disorientation of this sense is a “phantom limb sensation”

Phantom Limb Sensation • A phantom limb is the sensation that an amputated or missing limb is still attached to the body and is moving appropriately with other body parts. But why?

Vestibular Sense • The system for sensing body orientation and balance. • Fluid in the semicircle canals of the inner-ear maintain the body’s sense of balance. • A common disorientation of this sense is when you spin around and around, then stop. Your body has stopped moving, but the fluid hasn’t.

Thresholds

Detection Threshold or Absolute Threshold • The minimum intensity of energy required to produce sensation in a receptor cell at least 50% of the time

Taste: 1 gram of table salt in 500 liters of water • Smell: 1 drop of perfume diffused throughout a three room apartment • Touch: The wing of a bee falling on your cheek from a height of 1 centimeter • Hearing: The tick of a watch from 6 meters away • Vision: A candle flame on a clear night, 30 miles away

Difference Threshold or Just Noticeable Difference • The smallest change in stimulation that you can detect

Ernst Weber and Weber’s Law • The greater the magnitude of the stimulus, the larger the difference must be in order to be noticed • IE. If you are carrying 20 lbs. and add 5 lbs., it’s noticeable. If you are carrying 100 pounds and add 5 pounds, it may not be noticeable. You may need to add 20 lbs. to 100 pounds to make it noticeable.

Sensory Adaptation • Diminished sensitivity as a result of constant and unchanging stimulation. • You jump into a swimming pool of cold water, but eventually you “get used to it”. Or, you wear your glasses so often that you sometimes forget that they are on.

Selective Attention • Focusing conscious awareness on a particular stimulus while excluding others. • With so much stimulus bombarding our senses every second, we can’t respond to everything, all of the time. Listening to this lecture, you have chosen to ignore the feel of your shirt on your skin, ignored the sound of the heater, ignored the temperature of the room.

IE. It is estimated that our combined five senses take in over 11 million bits of information every second, of which we consciously process about 40.

Cocktail-Party Phenomenon • Describes instances when your attention will involuntarily switch when you hear or see something familiar. • IE. You are at a party, paying close attention to a conversation with a young lady. Someone in a separate conversation across the room says the name “Chris”. Without thinking about it, you hear the name and are momentarily distracted.

Subliminal Perception • Thresholds imply that there must be stimulus below and beyond our current levels of detection. Can human behavior be influenced by stimulus that is below or beyond our level of awareness? Subliminal Perception

Extrasensory Perception • Some people claim to have extra powers of perception, or the ability to respond to an unknown event that is not presented to any of the known senses. • Parapsychology

Examples of Extrasensory Perception • Telepathy: Transfer of information on thoughts or feelings between individuals by means other than the five classical senses • Precognition: Perception of information about future places or events before they occur. • Clairvoyance: Obtaining information about places or events at remote locations, by means unknown to current science.

Clairvoyance and Precognition?

The telephone rings and you know who it is.

You know what someone is about to say to you before they say the words.

You get a hunch or knowing about something and it turns out to be correct.

You get a sudden urge to go somewhere or do something, and when you do that thing, and it turns out to be the right thing that you should have done. And you are pleased.

You get a sudden urge to go somewhere or do something, and you ignore it or don't do it, and it turns out that you should have. And you regret it.

You can understand someone's true inner feelings even though on the outside they are hiding them.

You have a feeling that there is a presence or that someone or something behind the scene is helping you.

When something happens in your life, either good or not so good, and you suddenly understand a higher purpose behind it.

You sometimes hear a soft inner voice tipping you off about things happening in your life or in the life of someone else.

Sensation and Perception