Chapter 9: Sensation and Perception

**discrimination threshold**

which is the point at which one can distinguish the difference between two stimuli.

Detection thresholds

are the levels of a signal or measurement that must be met before being considered valid.

**absolute threshold**

the minimum amount of stimulation needed to detect a stimulus and cause the neuron to fire 50 percent of the time.

Afterimage

is an optical illusion in which an image continues to appear in one's vision after the exposure to the original image has ceased.

Habituation

is the process by which we become accustomed to a stimulus, and notice it less and less over time.

Subliminal perception

is a form of preconscious processing that occurs when we are presented with stimuli so rapidly that we are not consciously aware of them.

Sensory coding

is the process by which receptors convey such a range of information to the brain.

Synesthesia

is a neurological condition in which stimulation of one sense leads to automatic activation of another sense; for example, one might "hear "colors.

David Hubel

________ (1926- 2013) and Torsten Wiesel (1924),- through experiments with cats, determined that mammals, including humans, will develop normal vision along these lines so long as any impairments are corrected during the critical period, the first months after birth.

Gustation

is also a chemical sense.

Feature detector neurons

________ "see "different parts of the pattern, such as a line set at a specific angle to the background.

Symmetry

the tendency to perceive forms that make up mirror images.

Relative size

refers to the fact that images that are farther from us project a smaller image on the retina than do those that are closer to us.

Relative clarity

is a perceptual clue that explains why less distinct, fuzzy images appear to be more distant.

Monocular depth cues

are those that we need only one eye to see.

Perceptual processes

how our mind interprets these stimuli.

Law of Prägnanz

is a Gestalt psychology principle which states that the mind will attempt to simplify and organize complex stimuli into the simplest and most organized form possible.

Dichromats

are people who can not distinguish along the red /green or blue /yellow continuums.

Olfaction

is a chemical sense.

Perception

refers to the way in which we recognize, interpret, and organize our sensations.

Dishabituation

occurs when a change in the stimulus, even a small change, causes us to notice it again.

inner ear

is also responsible for balance and contains vestibular sacs, which have receptors sensitive to tilting.

Gestalt approach

to form perception is based on a top- down theory.

Retinal convergence

is a depth cue that results from the fact that your eyes must turn inward slightly to focus on near objects.

Similarity

the tendency to prefer grouping like objects together.

binocular disparity

The complement to stereopsis is ________, which results from the fact that the closer an object is, the less similar the information arriving at each eye will be.

Auditory input

in the form of sound waves, enters the ear by passing through the outer ear, the part of the ear that is on the outside of your head, and into the ear canal.

Stereopsis

refers to the three- dimensional image of the world resulting from binocular vision.

Gustav Fechner

the founder of psychophysics, in addition to contributing to Webers Law determined that the perceived brightness /loudness of a sensation is proportional to the logarithm of its actual intensity.

Adaptation

is an unconscious, temporary change in response to environmental stimuli.

Sensory organs

have specialized cells, known as receptor cells, which are designed to detect specific types of energy.

Transduction

is a process in which energy from one form is transformed into another.

retina

is at the back of the eye and serves as the screen onto which the proximal stimulus is projected.

Phi

(________ phenomenon); a motion picture, where still pictures move at a fast enough pace to imply movement (stroboscopic effect); and still light that appears to twinkle in darkness (autokinetic effect)

skin

has cutaneous and tactile receptors that provide information about pressure, pain, and temperature.

Visual sensation

occurs when the eye receives light input from the outside world.

Smells

evoke memories because the amygdala and hippocampus are connected to olfactory nerves.

Motion parallax

is the difference in the apparent movement of objects at different distances, when the observer is in motion.

Taste buds

________ provide information to the medulla oblongata, then the pons and thalamus.

Serial processing

occurs when the brain computes information step- by- step in a methodical and linear matter, while parallel processing happens when the brain computes multiple pieces of information simultaneously.

Proximity

the tendency to see objects near each other as forming groups.

Optic nerves

are the neural pathways that connect the eye to the brain.

quantitative information

is coded by the number of cells firing.

Tactile receptors

are specialized nerve endings in the skin that detect light touches, vibrations and even pain.

neural impulses

Through a process called transduction, the receptors convert the input, or stimulus, into ________, which are sent to the brain.

sensory system

Information becomes more complex as it travels through the ________, is known as convergence and occurs across all ________.

Inattentional blindness

also known as change blindness, demonstrates a potential weakness of selective attention.

Deafness

can occur from damage to the ear structure or the neural pathway.

This theory takes into consideration that there are four possible outcomes on each trial in a detection experiment

the signal (stimulus) is either present or it is not, and the participants respond that they can detect a signal or they cannot

Every stimulus has two dimensions

what it is (its qualitative dimension) and how much of it there is (its quantitative dimension)

Young-Helmholtz or trichromatic theory

According to this theory, the cones in the retina of the eye are activated by light waves associated with blue, red, and green

Shadowing

The participant is instructed to repeat only one of the conversations

Sensation

is the process of taking in information from the environment.

**psychophysics**

the branch of psychology that deals with the effects of physical stimuli on sensory response, researchers determine the smallest amount of sound, pressure, taste, or other stimuli that an individual can detect.

**Single-cell recording**

is a technique by which the firing rate and pattern of a single receptor cell can be measured in response to varying sensory input.

Bipolar cells

are neurons in the eye that carry signals from photoreceptors to ganglion cells

Amacrine cells

are interneurons in the retina that modulate visual responses and help relay information between bipolar cells, ganglion cells, and other retinal neurons.

**Feature detector**

neurons “see” different parts of the pattern, such as a line set at a specific angle to the background.

**opponent process theory**

contends that cells within the thalamus respond to opponent pairs of receptor sets—namely, black/white, red/green, and blue/yellow.

**Place theory**

asserts that sound waves generate activity at different places along the basilar membrane.

**Frequency theory**

in hearing states that we sense pitch because the rate of neural impulses is equal to the frequency of a particular sound.

**Deafness**

can occur from damage to the ear structure or the neural pathway.

**Conductive deafness**

refers to injury to the outer or middle ear structures, such as the eardrum.

**Kinesthesis**

found in the joints and ligaments, transmits information about the location and position of the limbs and body parts.

**Synesthesia**

is a neurological condition in which stimulation of one sense leads to automatic activation of another sense; for example, one might “hear” colors.

**Dishabituation**

occurs when a change in the stimulus, even a small change, causes us to notice it again.

**selective attention**

by which we try to attend to one thing while ignoring another.

**cocktail party phenomenon**

which refers to our ability to carry on and follow a single conversation in a room full of conversations.

**Constancy**

is another important perceptual process.

**Closure**

the tendency to see closed objects rather than those that are incomplete

**Continuity**

the tendency to perceive fluid or continuous forms, rather than jagged or irregular ones

**Symmetry**

the tendency to perceive forms that make up mirror images

**Similarity**

the tendency to prefer grouping like objects together

**Proximity**

the tendency to see objects near each other as forming groups

**Retinal convergence**

is a depth cue that results from the fact that your eyes must turn inward slightly to focus on near objects.

**Motion parallax**

is the difference in the apparent movement of objects at different distances, when the observer is in motion.

**Relative clarity**

is a perceptual clue that explains why less distinct, fuzzy images appear to be more distant.

**Aerial perspective**

another perceptual cue, is based on the observation that atmospheric moisture and dust tend to obscure objects in the distance more than they do nearby objects.

**Linear perspective**

is a monocular cue based on the perception that parallel lines seem to draw closer together as the lines recede into the distance.

**Interposition**

also known as occlusion, which occurs when a near object partially blocks the view of an object behind it.

**Bottom-up processing**

achieves recognition of an object by breaking it down into its component parts.

**Visual perception**

is quite complex.