Presentation on theme: "Sensation and Perception. “Everything you see or hear or experience in any way at all is specific to you. You create a universe by perceiving it, so everything."— Presentation transcript:
“Everything you see or hear or experience in any way at all is specific to you. You create a universe by perceiving it, so everything in the universe you perceive is specific to you.” – Douglas Adams
Sensation The process of taking in information from the environment
Transduction The process of changing raw sensory data into an electrochemical message that will be sent to the brain for interpretation.
Perception How we recognize, interpret, and organize our sensations
Input comes primarily from these five external senses: – Visual (Eyes) – Audio (Ears) – Cutaneous/Tactile (Touch) – Olfaction (Smell) (Nose) – Gustation (Taste) (Tongue)
Kinesthetic Sense The kinesthetic sense monitors the position and movements of muscles, bones, and joints. Receptors in the joints and tendons send the brain information about the angle of your limbs.
Vestibular Sense The system for balance. Fluid in the semicircle canals of the inner-ear maintain the body’s sense of balance.
Detection Threshold or Absolute Threshold The minimum intensity of energy required to produce sensation in a receptor cell at least 50% of the time
Difference Threshold or Just Noticeable Difference The smallest change in stimulation that you can detect
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.
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.
Cornea transparent protective coating over the front part of the eye
Iris the colored part of the eye – this muscle dilates or contracts the pupil to allow more or less light to enter
Pupil the small, adjustable center of the iris that allows light to enter the eye
Lens flexible enough to focus on objects near or far (accommodation) – if an object is very close is gets smaller and rounder; if an object is further away, it get larger and wider
Retina The inner lining of the back of the eyeball. The lens focuses an image from the outside world on the retina, and the retina in turn transduces the image.
Fovea On the retina, directly behind the lens. The area of sharpest picture.
Acuity – the sharpness of vision Nearsightedness – the misshapen eyeball focuses light rays in front of the retina – you will see near objects well, but not far away objects Farsightedness – the light rays from nearby objects reach the retina before they have been focused – you will see far objects better than near objects
Rods and Cones In the retina. Rods determine shades of light and dark and detect motion. Cones determine color.
Optic Nerve Carries the transduced visual information from the eye and sends it to the brain for processing.
Blind Spot The area closest to the optic nerve, that has no receptor cells. Also known as the optic disc.
Optic Chiasm The point in the brain at which messages from the visual fields are split to the appropriate areas of the brain – Prosopagonosia - stroke victim disorder in which victims cannot recognize faces, but can still see well and recognize emotions on faces
Color Vision There are two theories of color vision: – Trichromatic Theory – Opponent-Process Theory
Young-Helmholtz Theory Trichromatic Theory Rods and cones are pre-set to be sensitive to RED, GREEN, and BLUE. All of the colors that we see are combinations of those three colors.
All other colors can be derived by combining these three.
Opponent-Process Theory Sensory receptors in the retina come in pairs: – Red/Green – Yellow/Blue – Black/White
Opponent-Process Theory If one sensor is stimulated, the other is inhibited If one sensor is over-stimulated, and fatigues, the paired sensor will be activated, causing an afterimage If a person is missing a particular pair of sensors, they will be colorblind to those hues – Dichromatic Color Blindness have difficulty seeing shades of red and green, or yellow and blue
Hue – the color that we see is determined by the wavelength (the distance from one wave peak to the next) of the light wave that the eye is receiving
Brightness is influenced by the height of the waves (amplitude) of light that are received by the eye
The shorter the wavelength, more bluish colors The longer the wavelength, more reddish colors The higher the wave, more yellowish The lower the wave, more greenish
Figure/Ground Dynamic The ability to distinguish different objects from one another Analyzing separate information allows us to re-act to each individual object accordingly – Camouflage – when figures blend into the background
Gestalt Rules – Gestalt Psychologists focused on how we normally perceive images as groups, not isolated elements – Several factors influence how we will group objects: Proximity Similarity Continuity Closure
Proximity When objects are close together we tend to perceive them as together rather than separate
Constancy Despite changes in distance or lighting, objects still maintain their original properties – Size Constancy – Shape Constancy – Brightness Constancy
Size Constancy Objects closer to us will produce bigger images on our retinas, and as they move away they project a smaller image. The actual size of the object does not change. – IE. When a man is right in front of us, he is 6 ft. tall. As he walk further and further away, his image gets smaller. He hasn’t shrunk; he is still 6 ft. tall.
Shape Constancy Objects viewed from different angles will produce different shapes on our retina. Though we may change our position, the shape doesn’t change. – IE. Looking at the top of a glass one way makes it look round; from another angle it looks elliptical. The actual shape hasn’t changed…it is still round.
Brightness Constancy We perceive objects as having a constant color, despite lighting, shading, etc. – A brick wall is still red, whether bright sunlight is on it, or darkness has made it look gray.
Depth Cues Depth Cues allow us to perceive the world in three dimensions. – Monocular Cues are depth cues that do not depend on having two eyes working in conjunction together – Binocular Cues are depth cues that depend on having two eyes working in conjunction with each other
Linear Perspective Parallel lines seem to converge the further they get from us. The gradual reduction of image size as distance from the object increases Vanishing Point – where two parallel lines connect in the distance
Binocular Disparity Each of our eyes sees an object from a slightly different angle and projects that image onto the retina. The closer an object is, the further apart the two retinal images are. Further, closer images.