Chapter 4 Unit 1

• Psychophysics


  The study of how physical stimuli translate into our psychological experience.
• Perception


  The selection, organization, and interpretation of sensory input.
• Sensation


  The stimulation of sense organs.
• Stimulus


  Any detectable input from the environment.
• Absolute Threshold


  The minimum intensity a stimulus can be and still be detected by a human (50% of the time).
• Just Noticeable Difference


  The smallest difference in intensity between two senses that a sense can detect (50% of the time).
• Signal-Detection Theory


  The detection of stimuli depends on both sensory and decision processes.
• Subliminal Perception


  The registration of sensory input without conscious awareness.
• Sensory Adaptation


  A gradual decline in sensitivity to prolonged stimulation.
• Light

  A form of electromagnetic radiation that travels as a wave moving at the speed of light.
• Amplitude


  The height of a wave. Affects brightness of a light and loudness of sound.
• Wavelength


  The distance between peaks in a wave. Affects color of a light and pitch of a sound.
• Retina


  Neural tissue in the eye that receives light, processes images, and sends visual information to the brain.
• Cornea


  Transparent "window" that light enters the eye through.
• Lens


  A transparent eye structure that focuses the light rays falling on the retina.
• Nearsightedness


  When close objects are seen clearly but distant objects are not. The light focused by the lens is focused in front of the retina.
• Farsightedness


  When distant objects are seen clearly but close objects are not. The light focused by the lens is focused behind the retina.
• Iris


  The colored ring of muscle that regulates the amount of light that enters the light.
• Pupil


  The opening in the center of the iris that allows light to enter into the rear chamber of the eye.
• Optic Disk


  A hole in the retina where the optic nerve fibers exit the eye.
• Cones


  Visual receptors in the retina that play a role in daytime and color vision.
• Rods


  Visual receptors in the retina that play a role in nighttime and peripheral vision.
• Ganglion Cell


  Neuron that is stimulated in the retina by information received by the cones and rods of the retina.
• Fovea


  Tiny spot in the center of the retina that contains only cones.
• Dark Adaptation


  When the eyes become more sensitive to light in low illumination.
• Light Adaptation


  When the eyes become less sensitive to light in high illumination.
• Receptive Field


  Area of the retina that, when stimulated, affects the firing of a specific cell
• Optic Chiasm


  The point at which the optic nerves from the inside half of each eye cross over each other and then project to the opposite halves of the brain.
• Feature Detectors


  Neurons that respond selectively to very specific features of more complex stimuli.
• Subtractive Color Mixing


  Removing some wavelengths of light, leaving less light than was originally there.
• Additive Color Mixing


  Putting more light into a mixture than exists in any one lone light.
• Trichromatic Theory of Color Vision


  The eye contains specialized receptors to receive differing wavelengths of red, blue, and green light.
• Color Blindness


  Deficiencies in the ability to distinguish among colors.
• Complementary Colors


  Two colors that when mixed produce gray tones.
• Afterimage


  A visual image that persists after the visual stimulus has been removed.
• Opponent Process Theory of Color Vision


  Color perception depends on receptors that make opposite responses to three pairs of colors.
• Reversible Figure


  A drawing that is compatible with two interpretations that can shift back and forth.
• Perceptual Set


  A readiness to perceive a stimulus in a certain way.
• Inattentional Blindness


  Failure to see visible objects because your focus is elsewhere.
• Feature Analysis


  Process of detecting specific elements in visual input and assembling them into a more complex form.