Unit 3: Sensation and Perception (copy)

the minimum difference between any two stimuli that a person can detect 50 percent of the time—has been reached.

Difference threshold

is the receipt of messages that are below one’s absolute threshold for conscious awareness.

Subliminal stimulation

there is no actual absolute threshold because the threshold changes with a variety of factors, including fatigue, attention, expectations, motivation, and emotional distress.

signal detection theory

the weakest level of a stimulus that can be correctly detected at least half the time.

Absolute threshold

permits you to focus your attention on informative changes in your environment without being distracted by irrelevant data such as odors or background noises.

Sensory adaptation

refers to the transformation of stimulus energy to the electrochemical energy of neural impulses.

Transduction

is the process of selecting, organizing, and interpreting sensations, enabling you to recognize meaningful objects and events.

Perception

is caused by an irregularity in the shape of the cornea and/or the lens.

Astigmatism

Rods and cones both synapse with a second layer of neurons in front of them in your retina.

Bipolar cells

When it suddenly becomes dark, your gradual increase in sensitivity to the low level of light

Dark adaptation

Where the optic nerve exits the retina, there aren’t any rods or cones, so the part of an image that falls on your retina in that area is missing.

Blind spot

The thalamus then routes information to the primary visual cortex of your brain, where specific neurons

Feature detectors

Simultaneous processing of stimulus elements

Parallel processing

certain neurons can be either excited or inhibited, depending on the wavelength of light, and complementary wavelengths have opposite effects.

Ewald Hering’s opponent-process theory

is the primary sensory modality for human language.

Hearing

is measured in logarithmic units of pressure called decibels (dB).

Amplitude

determine the highness or lowness of the sound

Pitch

The process by which you determine the location of a sound

sound localization

the position on the basilar membrane at which waves reach their peak depends on the frequency of a tone.

Georg von Békésy’s place theory

the rate of the neural impulses traveling up the auditory nerve matches the frequency of a tone, enabling you to sense its pitch.

frequency theory

is a loss of hearing that results when the eardrum is punctured or any of the ossicles lose their ability to vibrate.

Conduction deafness

results from damage to the cochlea, hair cells, or auditory neurons.

Nerve (sensorineural) deafness

as a general term for four classes of tactile sensations: touch/pressure, warmth, cold, and pain.

Somatosensation

results from repeated gentle stimulation of pain receptors, a tickle results from repeated stimulation of touch receptors, and the sensation of wetness results from simultaneous stimulation of adjacent cold and pressure receptors.

Itching

is necessary for normal development and promotes a sense of well-being.

Touch

Ronald Melzack and Patrick Wall’s \________ attempts to explain the experience of pain.

gate-control theory

is the system that enables you to sense the position and movement of individual parts of your body.

Kinesthesis

is your sense of equilibrium or body orientation.

vestibular sense

are called chemical senses because the stimuli are molecules.

Gustation (taste) and olfaction (smell)

are most concentrated not only on your tongue in taste buds embedded in tissue called fungiform papillae, but are also on the roof of your mouth and the opening of your throat.

Taste receptor cells

have an average number of taste buds, nontasters have fewer taste buds, and supertasters have the most.

Tasters

are more sensitive than others to bitter, spicy foods and alcohol, which they find unpleasant.

Supertasters

your sensory receptors detect external stimulation and send these raw data to the brain for analysis.

Bottom-up processing

You focus your awareness on only a limited aspect of all you are capable of experiencing.

Selective attention

takes what you already know about particular stimulation, what you remember about the context in which it usually appears, and how you label and classify it, to give meaning to your perceptions.

Top-down processing

Where you perceive a conflict among senses, vision usually dominates.

Visual capture

which is the illusion of movement created by presenting visual stimuli in rapid succession.

phi phenomenon

The figure is the dominant object, and the ground is the natural and formless setting for the figure.

Figure–ground relationship

the nearness of objects to each other, is an organizing principle.

Proximity

states that we tend to fill in gaps in patterns.

Principle of closure

states that like stimuli tend to be perceived as parts of the same pattern.

Principle of similarity

or continuation states that we tend to group stimuli into forms that follow continuous lines or patterns.

Principle of continuity

are discrepancies between the appearance of a visual stimulus and its physical reality.

Optical or visual illusions

is the ability to judge the distance of objects.

Depth perception

are clues about distance based on the image of one eye, whereas binocular cues are clues about distance requiring two eyes.

Monocular cues

which is the slightly different view the two eyes have of the same object because the eyes are a few centimeters apart.

Retinal disparity

involves images of objects at different distances moving across the retina at different rates.

Motion parallax

of familiar objects provides a cue to their distance when the closer of two same-size objects casts a larger image on your retina than the farther one.

Relative size

or overlap can be seen when a closer object cuts off the view of part or all of a more distant one.

Interposition

can be seen when closer objects appear sharper than more distant, hazy objects.

Relative clarity

provides a cue to distance when closer objects have a coarser, more distinct texture than faraway objects that appear more densely packed or smooth.

Texture gradient

provides a cue to distance when closer objects have a coarser, more distinct texture than faraway objects that appear more densely packed or smooth.

Texture gradient

or elevation can be seen when the objects closest to the horizon appear to be the farthest from you.

Relative height

provides a cue to distance when parallel lines, such as edges of sidewalks, seem to converge in the distance.

Linear perspective

can be seen when the closer of two identical objects reflects more light to your eyes.

Relative brightness

such as the Müller-Lyer illusion and the Ponzo illusion, in which two identical horizontal bars seems to differ in length, may occur because distance cues lead one line to be judged as farther away than the other.

Optical illusions