What is transduction?	The conversion of one form of energy into another. In sensation, receptors convert stimulus energy such as light or sound waves into neural impulses.
What is the absolute threshold?	The minimum stimulus intensity a person can detect 50% of the time.
What does Weber's law state?	Two stimuli must differ by a constant proportion, not a constant amount, to be perceived as different, so the just noticeable difference grows with the size of the stimulus.
What does signal detection theory add to the idea of a fixed threshold?	Whether we detect a faint stimulus depends on our expectations, experience, motivation and alertness, not only on the stimulus strength.
What is sensory adaptation?	Reduced sensitivity to an unchanging stimulus over time (e.g., no longer noticing the smell of a room after a few minutes).
How do rods and cones differ?	Rods detect black, white and gray and work in dim light and peripheral vision. Cones detect color and fine detail in good light and cluster in the fovea.
Why does each eye have a blind spot?	The point where the optic nerve leaves the eye has no rods or cones, so no image is detected there.
What does the trichromatic (Young-Helmholtz) theory propose?	The retina has three types of cones, most sensitive to red, green and blue light, and their combined activity produces every color we perceive.
What does opponent-process theory explain that trichromatic theory cannot?	Afterimages. Color is processed in opposing pairs (red-green, blue-yellow, black-white), so fatiguing one side of a pair makes you briefly see its opposite.
What are feature detectors?	Neurons in the visual cortex that respond to specific features such as edges, lines and angles, discovered by Hubel and Wiesel.
How does conduction hearing loss differ from sensorineural hearing loss?	Conduction loss is damage to the mechanical system that carries sound to the cochlea (eardrum, middle-ear bones). Sensorineural loss is damage to the cochlea's hair cells or the auditory nerve.
How does place theory explain pitch?	Different frequencies stimulate hair cells at different places along the cochlea's basilar membrane. It best explains high-pitched sounds.
How does frequency theory explain pitch?	The rate at which the auditory nerve fires matches the frequency of the sound wave. It best explains low-pitched sounds.
What does gate-control theory propose about pain?	The spinal cord contains a neural gate that can block pain signals or let them through to the brain, which is why rubbing a bumped knee can ease the pain.
What does the vestibular sense monitor?	Head position and movement, using the semicircular canals and vestibular sacs in the inner ear, to keep you balanced.
What is kinesthesis?	The sense of the position and movement of your own body parts, from receptors in muscles, tendons and joints.
How does top-down processing differ from bottom-up processing?	Bottom-up processing builds a perception from raw sensory input. Top-down processing interprets that input using expectations, knowledge and context.
What is a perceptual set?	A mental predisposition to perceive one thing and not another, shaped by expectations, context and experience.
What is figure-ground organization?	The Gestalt tendency to see an object (the figure) standing out from its surroundings (the ground).
Which Gestalt principle leads us to fill in gaps and see a complete shape?	Closure.
What is retinal disparity?	A binocular depth cue: the greater the difference between the images on the two retinas, the closer the object.
What is convergence as a depth cue?	A binocular cue based on how far the eyes turn inward to focus on an object. The more they converge, the nearer the object.
Which monocular depth cue makes parallel railway lines seem to meet in the distance?	Linear perspective.
What is perceptual constancy?	Perceiving objects as keeping the same size, shape, color and brightness even when the image on the retina changes with distance, angle or lighting.
What is inattentional blindness?	Failing to see a visible object because attention is focused elsewhere, as when viewers counting basketball passes miss a person in a gorilla suit (Simons and Chabris).