Psych Chapter 4: Sensation and Perception

sensation

The process of receiving stimulus energies from the external environment and transforming those energies into neural energy.

perception

The process of organizing and interpreting sensory information so that it has meaning.

bottom-up processing

The operation in sensation and perception in which sensory receptors register information about the external environment and send it up to the brain for interpretation.

top-down processing

The operation in sensation and perception, launched by cognitive processing at the brain's higher levels, that allows the organism to sense what is happening and to apply that framework to information from the world.

sensory receptors

Specialized cells that detect stimulus information and transmit it to sensory (afferent) nerves and the brain.

photoreception

Detection of light, perceived as sight.

mechanoreception

Detection of pressure, vibration, and movement, perceived as touch, hearing, and equilibrium.

chemoreception

Detection of chemical stimuli, perceived as small and taste.

synaesthesia

Describes an experience in which one sense induces an experience in another sense.

Phantom limb pain

A confused sense where you feel pain in an area where sensory receptors are gone. (Ex. missing a limb) Therapy includes mirror therapy giving the illusion of still having the limb there.

absolute threshold

The minimum amount of stimulus energy that a person can detect. Refers to the intensity of stimulation detected 50% of the time.

noise

Irrelevant and competing stimuli - not only sounds but also any distracting stimuli for our senses.

difference threshold

The degree of difference that must exist between two stimuli before the difference is detected.

Weber's law

The principle that two stimuli must differ by a constant minimum percentage (rather than a constant amount) to be perceived as different.

subliminal perception

The detection of information below the level of conscious awareness.

signal detection theory

A theory of perception that focuses on decision making about stimuli in the presence of uncertainty.

information aquisition

Acquiring information in order to make a decision.

criterion

Basis for making a judgement from the available information.

attention

The process of focusing awareness on a narrowed aspect of the environment.

selective attention

The process of focusing on a specific aspect of the environment while ignoring others.

cocktail party effect

The ability to concentrate on one voice among many in a crowd.

Stroop effect

Named for John Ridley Stroop - refers to the way that automatically reading a color name can make it difficult to name the color in which the word is printed.

Novel stimuli

New, different, or unusual stimuli that often attract our attention.

Emotion-induced blindness

When we encounter an emotionally charged stimulus, we often fail to recognize a stimulus that is presented immediately after it.

Inattentional blindness

The failure to detect unexpected events when our attention is engaged by a task.

perceptual set

A predisposition or readiness to perceive something in a particular way.

sensory adaptation

A change in the responsiveness of the sensory system based on the average level of surrounding stimulation.

extrasensory perception

(ESP) When a person can read another person's mind or perceive future events in the absence of concrete sensory input.

Parapsychology - scientific study of ESP

light

A form of electromagnetic energy that can be described in terms of wavelengths.

wavelengths

The distance from the peak of one wave to the peak of another wave. Visible light ranges from 400 to 700 nano meters.

amplitude

The height of the wave that helps determine the brightness of a stimulus.

For the auditory system, measured in decibels (dB), is the amount of pressure the sound wave produces relative to a standard.

purity (of a wavelength)

Determines the perceived saturation, or richness, of a visual stimulus.

sclera

White, outer part of eye that helps to maintain the shape of the eye and to protect it from injury.

iris

Colored part of the eye

pupil

The opening on the center of the iris (which appears black). Opens to let more light in, closes to let less light in.

cornea

A clear membrane just in front of the eye that helps bring an image into focus. (Bends the light)

lens

A transparent and somewhat flexible, disk-shaped structure filled with a gelatin-like material which also helps bring an image into focus. (Fine-tunes things)

retina

The multilayered light-sensitive surface in the eye that records electromagnetic energy and converts it to neural impulses for processing in the brain.

rods

The receptor cells in the retina that are sensitive to light but not very useful for color vision. (average of 120 million rods)

cones

The receptor cells in the retina that allow for color perception.

fovea

The most important part of the retina - a tiny area in the center of the retina at which vision is at its best - only contains cones.

optic nerve

The structure at the back of the eye, made up of axons of the ganglion cells, that carries visual information to the brain for further processing.

blind spot

The place of the retina where the optic nerve leaves the eye on its way to the brain

optic chiasm

An area in the brain where the optic nerve fibers divide, and approximately half of the nerve fibers cross over the midline of the brain.

feature detectors

Neurons in the brain's visual system that respond to particular features of a stimulus.

parallel processing

The stimulus distribution of information across different neural pathways.

binging

In the sense of vision, the bringing together and integration of what is processed by different neural pathways or cells.

trichromatic theory

Theory stating that color perception is produced by three types of cone receptors in the retina that are particularly sensitive to different, but overlapping, ranges of wavelengths.

color blindness

Defective color vision - the nature of color blindness depends on which of the three cones (red, blue, or green) is inoperative.

afterimage

Sensation that remains after a stimulus is removed.

opponent-process theory

Theory stating that cells in the visual system respond to complementary pairs of red-green and blue-yellow colors; a given cell might be excited by red and inhibited by green, whereas another cell might be excited by yellow and inhibited by blue.

figure-ground relationship

The principle by which we organize the perceptual field into stimuli that stand out (figure) and those that are left over (ground).

gestalt psychology

A school of thought interested in how people naturally organize their perceptions according to certain patterns. Gestalt = configuration/form

gestalt principles

Law of proximity - how you group things that are nearby to each other

Law of similarity - how you group things based on similarity

Law of closure - how your minds fills in the gaps

Law of continuity - how you perceive things on whether they continue or not

Law of connectedness - how your mind perceives how things are connected

depth perception

The ability to perceive objects three-dimensionally.

binocular cues

Depth cues that depend on the combination of the images in the left and right eyes and on the way the two eyes work together.

convergence

A binocular cue to depth and distance in which the muscle movements in our two eyes provide information about how deep and/or far away something is.

monocular cues

Powerful depth cues available from the image in one eye, either the right or the left.

familiar size

This cue to the depth and distance of objects is based on what we have learned from experience about the standard sizes of objects

height in the field of view

All other things being equal, objects positioned higher in a picture as seen as farther away.

linear perspective and relative size

Objects that are farther away take up less space on the retina. So, things that appear smaller are perceived ti be farther away.

overlap

We perceive an object that partially conceals or overlaps another object as closer.

shading

This cue involves changes in perception due to the position of the light and the position of the viewer.

texture gradient

Texture becomes denser and finer the farther away is is from the viewer.

apparent movement (motion parallax)

The perception that a stationary object is moving.

perceptual constancy

The recognition that objects are constant and unchanging even though sensory input about them is changing.

size constancy

The recognition that an object remains the same size even though the retinal image of the object changes.

shape constancy

The recognition that an object retains the same shape even though its orientation to you changes.

color constancy

The recognition that an object retains the same color even though different amounts of light fall on it.

frequency

The number of cycles (full wavelengths) that pass through a point in a given time interval.

pitch

The perceptual interpretation of the frequency of a sound.

complex sounds

Sounds in which numerous frequencies of sound blend together.

Timbre

The tone saturation, or the perceptual quality of a sound.

outer ear

The outermost part of the ear, consisting of the pinna and the external auditory canal.

middle ear

The part of the ear that channels sound through the eardrum, hammer, anvil, and stirrup to the inner ear.

inner ear

The part of the ear that includes that oval window, cochlea, and basilar membrane and whose function is to convert waves into neural impulses and send them to the brain.

cochlea

A tubular, fluid-filled structure that is coiled up like a snail.

cochlear implant

A small electronic device that is surgically implanted in the ear and head which allows deaf or profoundly hard-of-hearing individuals to detect sound. They were specifically developed to replace damaged hair cells.

place theory

Theory on how the inner ear registers the frequency of sound, stating that each frequency produces vibrations at a particular spot on the basilar membrane.

frequency theory

Theory on how the inner ear registers the frequency of sound, stating that the perception of a sound's frequency depends on how often the auditory nerve fires.

volley principle

Modification of frequency theory stating that a cluster of nerve cells can fire neural impulses in rapid succession, producing a volley of impulses.

auditory nerve

The nerve structure that receives information about sound from the hair cells of the inner ear and carries these neural impulses to the brain's auditory areas.

sound shadow

Provides a barrier that reduces a sound's intensity.

cutaneous senses

Touch, temperature, and pain - receptors found all over the skin (our largest sensory system)

thermoreceptors

Sensory nerve endings under the skin that respond to changes in temperature at or near the skin and provide input to keep the body's temperature at 98.6 degrees Fahrenheit.

pain

The sensation that warns us of damage to our bodies.

prostaglandins

Stimulate the receptors and cause the experience of pain.

fast pathway

Fibers connect directly with the thalamus and then to the motor and sensory areas of the cerebral cortex. (Transmits sharp, localized pain)

slow pathway

Where pain information travels through the limbic system, a detour that delays the arrival of information at the cerebral cortex by seconds.

endorphins

Neurotransmitters that function as natural opiates in producing pleasure and pain. (Happy hormones) Released in the synapses of the slow pathway.

reasoning

The mental activity of transforming information to reach conclusions.

inductive reasoning

Reasoning from specific observations to make generalizations.

deductive reasoning

Reasoning from a general case that is known to be true to a specific instance.

decision making

The mental activity of evaluating alternatives and choosing among them.

two levels of decision making

System 1 - automatic system that involves processing that is rapid, heuristic, and intuitive (following your gut).

System 2 - controlled system that is slower, effortful, and analytical; involves conscious reflection about an issue.

confirmation bias

The tendency to search for and use information that supports our ideas rather than refutes them.

hindsight bias

The tendency to report falsely, after the fact, that we accurately predicted an outcome.

availability heuristic

A mental shortcut that occurs when people make judgments about the probability of an event by the ease with which examples come to mind.

base rate fallacy

The tendency to ignore certain information about general principles in favor of very specific but vivid information.

representativeness heuristic

A mental shortcut used when making judgments about the probability of an event based on stereotypes or similar prototypes.