Chapter IV: Sensation and Perception

Sensation is a neural process during which a stimulus causes receptors to dispatch messages to the brain.

Perception is a mental process that interprets messages dispatched from sensory organs.

Transduction is the conversion of physical energy into neural messages.

Sensory adaptation is the loss of acuteness of receptors when a stimulus remains unchanged for a long period of time.

Absolute threshold is the limit of intensity of a stimulus in order for it to be detected.

Different threshold is the limit of change in a stimulus in order for that change to be detected.

Signal detection theory is an explanation of how stimuli are detected by our sensory organs. It says that what we detect depends on our bias, emotions and expectations at that time.

Retina is a part of the eyeball that is a thin layer on the back containing photoreceptors.

Photoreceptors are neurons that specialize in deriving neural messages from incoming light.

Rods are photoreceptors that are sensitive to dim light.

Cones are photoreceptors that detect colors.

Fovea is a small spot on the retina where vision is primal.

Optic nerves are neurons that specialize in carrying messages from the eyes to the brain.

Blind spot is the area on the retina where optic nerves exit the eyeball that contains no photoreceptors.

Brightness is a perception caused by light intensity.

Color is a perception caused by the wavelength of human-visible light.

Electromagnetic spectrum is a continuum of radiations which travel at the speed of light.

Visible spectrum is an interval on the electromagnetic spectrum that can be detected by humans.

Trichromatic theory is an explanation for color perception postulating that there are three types of cones that sensitive to three different colors.

Opponent-process theory is the postulate that the visual cortex processes colors in complimentary pairs.

Afterimages are the sensations that remain even though their stimuli have gone.

Color blindness is a disorder that affects one’s ability to identify colors.

Frequency is a property of a wave that is the number of periods within a given interval. Hertz is a unit of frequency.

Amplitude is the height of the wave.

Tympanic membrane, aka eardrum, is a layer of tissues inside the ear that transmit sound vibrations to nearby tiny bones.

Cochlea is a spiral-shaped organ inside the ear where sound is transduced.

Basilar membrane is a layer of hair-like sensory tissues inside the cochlea responsible for transducing sound waves.

Pitch is the perception of sound wave frequency.

Loudness is a perception of sound wave amplitude.

Timbre is a perception of sound wave complexity.

Vestibular sense is the sense of comparing the body’s position to the direction of gravity.

Kinesthetic sense is the sense of the positions of body parts relative to each other.

Gustation is the sense of taste.

Skin senses is the sensory system incorporated into the skin that detects stimuli of pressure, temperature, texture and pain.

Gate-control theory is the idea that neural signals of pain can be blocked or jammed by other neural signals.

Conduction deafness is the inability to detect sound due to structural damage to the middle or inner ear.

Sensorineural deafness is the inability to detect sound due to damage to nerves or the brain.

Feature detectors are parts of the cortex devoted to analyzing certain stimuli that are responsible for picking up patterns from the incoming neural messages.

Bottom-up processing is perception based on characteristics of the stimulus.

Top-down processing is perception influenced by one’s expectation and memories.

Perceptual constancy is the ability to perceive that something has not changed even when viewed from different perspectives.

Illusions are usually visual stimuli that cause perception to incorrectly interpret patterns.

Ambiguous figures are images that are open to different perceptions.

Figure is the part of an image that attracts attention first and does so the most.

Ground, aka background, is the part of an image that attracts little attention.

Laws of perceptual grouping are Gestalt principles that explain how the brain perceives a group of stimuli.

Law of similarity is the Gestalt principle that says the brain tends to group similar objects together in perception.

Law of proximity is the Gestalt principle that says the brain tends to group objects near each other together in perception.

Law of continuity is the Gestalt principle that says the brain prefers continuous curves to disconnected figures.

Law of common fate is the Gestalt principle that says when the brain groups objects together, it believes that they share the same purpose or destination.

Law of Pragnanz is a Gestalt principle that says the brain prefers to perceive the simplest pattern possible because it requires the least amount of energy.

Binocular cues are visual data collected by both eyes that aid the perception of depth.

Monocular cues are depth information gathered by just one eye, e.g. relative size, shade, interposition, relative motion and atmospheric perspective.

Learning-based inference is the belief that perception is based primarily on learning rather than innate factors.

Perceptual set is the tendency to have certain perceptions in a particular situation.


12 responses »

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