Chapter 4: Sensation & Perception

• Sensation is the process of receiving stimuli from the environment, while perception involves brain processes organizing sensations to give them meaning
• Absolute threshold is the minimum amount of stimulus energy that a person can detect at least half the time (50%)
• Difference Threshold is the degree of difference that must exist between two stimuli before the difference is detected

  
  

  Just Noticeable Difference (JND) increases with stimulus magnitude
• Subliminal Perception is the detection of information below the level of conscious awareness
• Bottom-Up Processing involves sensory receptors registering information and sending it up to the brain for processing
• Top-Down Processing starts with our own sense of something happening and then applies it down to our framework of the world
• Rods are receptors in the retina sensitive to light
• Trichromatic Theory explains how we see colors based on three cone receptors: red, green, and blue
• Opponent-Process Theory states that we have four types of color receptors organized into complementary pairs (red-green and blue-yellow)
• Depth Perception involves seeing the world with two eyes
• Perceptual Illusions come from Gestalt Psychology and include concepts like figure-ground, law of proximity, and Muller-Lyer Illusion
• Perceptual Set is the way we expect to see something in an expected way, occurring even before we are presented with the stimulus
• Perceptual Constancy is the recognition that objects are constant and unchanging despite changing sensory input
• Sensory adaptation is a phenomenon in which sensory receptors become less responsive to constant stimuli over time
• Signal Detection Theory involves decision-making based on uncertainty
• Insight Learning by Kohler refers to those 'ah-ha' moments or light bulb moments
• Instinctive Drift is when instinctive behaviors take over, hindering learned behaviors
• Preparedness and Taste Aversion occur when eating or drinking something that makes you sick, leading to an aversion to that food or beverage
• Cones are sensitive to color. They are sensitive to different, but overlapping wavelength ranges
• Trichromatic Theory:

  • Short wavelengths: blue
  • Medium wavelengths: green
  • Long wavelengths: red
  • Combined wavelengths allows us to see different colors and is referred to as additive color mixing
• People (mostly men) who are color-blind only have two types of receptors and they are called dichromats, compared to trichromats
• Ganglion cells are responsible for seeing the opposing color.

  A cell may be excited by red and inhibited by green or excited by yellow and inhibited by blue.
• Binocular cues: cues about depth that depend on the combination of the images in the left and right eyes and the way they both work together

  • Convergence is a binocular cue: the muscles in your eyes help you see how close or far something is from you
• Monocular Cues: available from the image in one eye, either right or left

  • Familiar Size (we know distance from our world experience)
  • Linear Perspective (parallel lines recede into the distance, they seem to converge)
  • Texture Gradation (texture becomes denser and finer the farther away it is from the viewer)
• Figure Ground: Organize the perceptual field into stimuli that stand out (foreground) and those left over (background)
• Law of Proximity: Objects near each other are grouped together
• Law of Closure: Objects grouped together seen as whole
• Muller-Lyer Illusion: when 2 lines are the same length but have the illusion of being different lengths
• Horizontal-Vertical Illusion: Where the vertical line looks longer than the horizontal line even though they are the same length
• • Cocktail Party Effect: effect-focusing in on one person in a crowded room of people where there is a lot of noise
  • Stroop Effect: Automatic perception where it is difficult to name the colors in which words are printed in different colors