Chapter 5: Sensation And Perception Flashcards
Sensation
Stimulus detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain
Perception
Making “sense” of what our senses tell us; it is the active process of organizing the stimulus and giving it meaning
What is the difference between sensation and perception?
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Sensory transduction
The process where the characteristics of a stimulus are converted into nerve impulses
Psychophysics
Studies the relationship between the physical characteristics of stimuli and sensory capabilities (f.eks how low a sound can the human ear perceive)
Absolute threshold
The lowest intensity at which a stimulus can be perceived by a human 50 percent of the time
Decision criterion
A standard of how certain someone must be that a stimulus is present before they will say they can detect it
Signal detection theory
Concerned with the factors that influence sensory judgements
Difference threshold
Defined as the smallest difference between two stimuli that people can perceive 50 percent of the time
Weber’s law
States that the difference threshold (or JND) is directly proportional to the magnitude of the stimulus with which the comparison is being made
Sensory adaption
The diminishing sensitivity to an unchanging stimulus
Lens (eye)
Elastic structure that becomes thinner to focus on distant objects, and thicker to focus on nearby objects
Retina
Multilayered light-sensitive tissue at the rear of the fluid-filled eyeball
Myopia
Nearsightedness
Hyperopia
Farsightedness
Rods (eye)
- primarily black and white brightness receptors
- function best in dim light
Cones (eye)
- color receptors
- function best in bright illumination
Fovea
Small area in the center of the retina that contains no rods, but mainly densely packed cones
Optic nerve
Ganglion cells, whose axons are collected into a bundle to form the optic nerve
Visual acuity
Ability to see fine detail
Photo-pigments
Rods and cones translate light waves into nerve impulses through the action of protein molecules called photo-pigments
Dark adaptation
The progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination
Young-Helmholtz trichromatic theory
States that there are three types of color receptor in the retina
Hearing’s opponent-process theory
States that each of the three cone types responds to two different wavelengths
Dual-process theory
Combines the trichromatic and opponent-process theory to account for the color transduction process
Feature detectors (cells in retina)
Fire selectively in response to visual stimuli that has specific characteristics
Two principal characteristics of sound waves
1: frequency (number of sound waves or cycles per second)
hertz (Hz, the measure of cycles per second, 1Hz=1 cycles per sec)
2: amplitude (vertical size of the sound waves, depth between peaks and troughs)
Decibels (dB, measure of the physical pressures that occur at the eardrum)
Cochlea (ear)
Coiled, snail-shaped tube
Contains basilar membrane
Basilar membrane
Sheet of tissue that runs the length of cochlea
Organ of corti
Rests on basilar membrane
Contains thousands of tiny hair cells that are the actual sound receptors
Frequency theory of pitch perception
Nerve impulses sent to the brain match the frequency of the sound wave
Place theory of pitch perception
The specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a frequency coding cue
Gustation
The sense of taste
Olfaction
Sense of smell
Taste buds
Small bodies containing taste receptor cells concentrated along the tip, edges and back surface of the tongue
Olfactory system processing
Olfactory receptors that fire send their input to the olfactory bulb, which codes the signals in part via the area of the olfactory bulb which is excited
(Olfactory processing involves organizing olfactory neurons into groups representing the kinds of chemicals that have simulated them)
Pheromones
Chemical signals found in natural body scents
Orthonasal olfaction
Smelling something from outside your mouth
Retronasal olfaction
Smelling something from the inside of your mouth (heavily involved with our perception of flavor)
Cutaneous touch
The sense of touch arising from events on the skin surface (temperature and pressure)
Proprioception
Sensory input that provides info on the layout and movements of our limbs
Interoceptive touch
The sense of touch arising from receptors inside the body, usually blood vessels and organs
Haptics
The active use of touch and movement to explore objects and surfaces within reach
Sensory prosthetic devices
Provide sensory input that can, to some extent, substitute for what cannot be supplied by the persons sensory receptors
Synaesthesia
Mixing of the senses
Bottom-up processing
Individual elements of a stimulus are analysed and then combined to form a unified perception
Top-down processing
Sensory information is interpreted in light of existing knowledge, concepts, ideas and expectations
Figure-ground relations
Our tendency to organize stimuli into a central or foreground figure and a background
Gestalt laws of perceptual organization
Similarity, proximity, closure and continuity
Perceptual schema
A mental representation or image containing the critical and distinctive features of a person, object, event or other perceptual phenomenon
Perceptual Constantine
Allow us to recognize familiar stimuli under varying conditions
Monocular depth cues
Patterns of light and shadow, linear perspective, relative size
Binocular depth cues
Binocular disparity (each eye sees a slightly different image) Convergence (produced by feedback from the muscles that move your eyes inward to view a close object)
Stroboscopic movement
Illusory movement produced when a light is briefly flashed in darkness and then, a few milliseconds later, another light is flashed nearby
Illusions
Compelling, yet incorrect perceptions
Critical periods
Periods during which certain kinds of experiences must occur if perceptual abilities and the brain mechanisms that underlie them are to develop normally
