Sensation:
  • The process of bringing information from the outside world into the body and then to the brain for interpretation
  • Involves transducers (special receptor cells) that are involved in the process of transduction (converting stimuli into neural impulses)

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Perception:
  • The active process of selecting, organizing, and interpreting the information brought to the brains by the senses
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Bottom-Up Processing:
  • Where senses send information to our brain
Top-Down Processing:
  • Brain assembles the information to make sense of the impulses being sent to it

DETECTION
  • Absolute Threshold: Minimum stimulation needed to detect light, a sound, a pressure, taste or odor 50% of the time
  • Signal detection theory: The idea that predicting if a person detects a stimulus depends not only on the stimulus but also on our experience, expectations, motivation, and alertness
  • Subliminal stimulation: Stimulation just below our level of consciousness
    • Example: An image could be flashed so quickly that a person doesn’t even notice that they saw it
    • Difference Threshold: The minimum difference between to stimuli that can be detected at least 50% of the time
    • Weber’s Law: Two stimuli must differ by a constant minimum percentage (rather than a constant amount) to be perceived as different
      • Example: Weight must differ by 2% for a person to notice the difference
SELECTIVE ATTENTION
  • Selective Attention: Ability to focus conscious awareness on to a specific stimulus
    • Cocktail Party Effect: A person’s ability to single out one voice amidst many others
    • Inattentional Blindness: Ability to block out all but one piece of sensory input (focusing on only one thing)

    • Choice Blindness: People are unware of the choices or preferences they make

SENSORY ADAPTION
  • Sensory Adaption: A person’s diminishing sensitivity to a sensory stimulus
    • Example: A person spills some perfume in class, at first you notice it a lot but then at the end of class you do not notice it anymore but someone else walks in and smells the spilled perfume right away
STIMULUS INPUT: LIGHT ENERGY
  • Visible light important characteristics:
    • Frequency: The wavelength of the light wave, how frequently the waves hit
    • Amplitude: The intensity of the light wave, how strong the waves hit
    • Vision and how it works
      • Step 1: Gathering light
        • The eyes convert light energy into neural messages
      • Step 2: Processing inside the eye
        • Cornea -The transparent protective coating over the front part of the eye.
        • Pupil -small opening in the iris through which light enters the eye.
        • Iris -colored part of the eye.
        • Lens -transparent part of the eye inside the pupil that focuses light onto the retina.
        • Retina -lining of the eye containing receptor cells that are sensitive to light. Transduction occurs here.

      • Step 3: Transductionpsychpic3.png
        • Transduction – Process by which sensory signals are transformed into neural impulses.
        • Receptor cell - Specialized cell that responds to a particular type of energy.
        • Rods - Receptor cells in the retina responsible for night vision and perception of brightness.
        • Cones - Receptor cells in the retina responsible for color vision.
        • Fovea - Area of the retina that is the center of the visual field.
        • Optic nerve - The bundle of axons of ganglion cells that carries neural messages from each eye to the brain.
        • Blind spot - Place on the retina where the axons of all the ganglion cells leave the eye and where there are no receptors.
      • Step 4: Processing inside the brain
        • Brain has feature detectors, that detect features like angles, lines, edges, and movements
        • Works in parallel processing, which means that it takes on several tasks at the same time
    • Color Vision
      • Trichromatic theory: This theory states that the human retina contains three different receptors for color; one is most sensitive to red, one to green, and one to blue. These colors then combine to produce the perception of almost any color
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      • Opponent-process theory: States that three sets of color receptors respond in an either/or fashion to determine the color you experience
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Stare at the center dot then look away; you should see the American flg
      • Color-blindness: Some people do not have the ability to perceive hues
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People with colorblindness are unable to see the numbers inside of the circles
THE STIMULUS INPUT: SOUND WAVES
  • Hearing:
    • Amplitude: The height of the wave that determines the loudness of sound
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    • Frequency: Number of cycles per second in a wave
    • Pitch: Auditory experience corresponding primarily to frequency of sound vibrations that result in a higher or lower tone
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  • The Ear
    • Ear canal – Also called the auditory canal, carries sound waves into the ear.
    • Eardrum - A membrane at the end of the auditory canal. It vibrates due to sound waves.
    • Hammer, anvil, stirrup - The three small bones in the middle ear that relay vibrations of the eardrum to the inner ear.
    • Cochlea - Part of the inner ear containing fluid that vibrates which in turn causes the basilar membrane to vibrate. For psychology, this may be the most important part of the ear because this is where sound waves are converted into neural impulses.
    • Basilar membrane -Vibrating membrane in the cochlea of the inner ear; it contains sense receptors for sound.
    • Auditory nerve -The bundle of neurons that carries signals from each ear to the brain.
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  • Pitch Theories:
    • Place Theory: The theory that pitch is determined by the location of the greatest vibration of the basilar membrane
    • Frequency Theory: Theory that pitch is determined by the frequency with which hair cells in the cochlea fire
FORM PERCEPTION
  • Gestalt principal: Idea that the whole is greater than the individual parts that make up the whole
  • Figure-ground: We have the ability to look at a figure against a background, and know which part of the image is the background and what part of the image is the figure.
  • Humans tend to group similar things into groups:
    • Proximity – things close to one another are grouped together.
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    • Similarity – things alike are grouped.
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    • Continuity – we like things that are unbroken.
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    • Closure – we like to complete things that are not complete.
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    • Connectedness – we like things are linked or brought together.
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DEPTH PERCEPTION
  • Depth perception is the ability to see things in 3D which help humans gauge distance
    • This starts at a early age as shown the visual cliff experiment where babies would not crawl across a glass table because they understood that there was a drop off
  • Binocular cues:
    • Retinal disparity: the difference between the visual images that each eye perceives because of the different angles in which each eye views the world
  • Monocular cues:
    • Relative height – things seen higher up are perceived as farther away
    • Relative size – things small are perceived as farther away.
Notice the differences between the ducks and the house
Notice the differences between the ducks and the house
    • Interposition – when things are “stacked”, the one that’s covered up is farthest, the one that’s not covered is closest.
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    • Linear perspective – parallel lines, like railroad tracks, converge in the distance; the more they converge, the farther away.
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    • Light and shadow – close objects reflect more light, farther ones appear dimmer.
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    • Relative motion – while we move, things close to us appear to move fast in the opposite direction; things farther away appear to move very slowly or not at all.

MOTION PERCEPTION
  • Stroboscopic effect: People perceive a series of still photos (like a film) as having continuous motion
  • Phi phenomenon occurs when two lights are flashing alternately and it gives the perception that one light is moving back-and-forth

PERCEPUTAL CONSTANCY
  • Shape constancy is our tendency to expect things to retain their shape. A door viewed from different angles actually looks like a trapezoid, but our expectations are that it’s a rectangle.
  • Size constancy is our tendency to expect things to retain their size. A bus view from miles away looks small, but we expect it to be big enough for lots of people to fit inside.
  • Lightness constancy is our tendency to expect things to retain their lightness.
  • Color constancy is our tendency to expect things to retain their color.

PERCEPTUAL SET
  • Perceptual set:
    • What we have already seen and experienced, once we have a perceptual set in place it is hard to see what is actually there
  • Context:
    • When something is out of context we often misperceive it