ap psychology Unit 3: Sensation and Perception

Difference threshold

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

Subliminal stimulation

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

signal detection theory

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

Absolute threshold

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

Sensory adaptation

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

Transduction

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

Perception

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

Astigmatism

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

Bipolar cells

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

Dark adaptation

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

Blind spot

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.

Feature detectors

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

Parallel processing

Simultaneous processing of stimulus elements

Ewald Hering opponent process theory

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

Hearing

is the primary sensory modality for human language.

Amplitude

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

Pitch

determine the highness or lowness of the sound

sound localization

The process by which you determine the location of a sound

Georg von Békésy’s place theory

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

frequency theory

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

Conduction deafness

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

Nerve (sensorineural) deafness

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

Somatosensation

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

Itching

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.

Touch

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

gate-control theory

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

Kinesthesis

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

vestibular sense

is your sense of equilibrium or body orientation.

Gustation (taste) and olfaction (smell)

are called chemical senses because the stimuli are molecules.

Taste receptor cells

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.

Tasters

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

Supertasters

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

Bottom-up processing

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

Selective attention

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

Top-down processing

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.

Visual capture

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

phi phenomenon

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

Figure-ground relationship

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

Proximity

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

Principle of closure

states that we tend to fill in gaps in patterns.

Principle of similarity

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

Principle of continuity

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

Optical illusions/ visual illusions

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

Depth perception

is the ability to judge the distance of objects.

Monocular cues

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

Retinal disparity

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

Motion parallax

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

Relative size

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.

Interposition

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

Relative clarity

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

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

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

Relative height

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

Linear perspective

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

Relative brightness

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

Optical illusions

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.

sensation

the passive process of bringing information from the outside world into the body and to the brain.

ex: Touching a table

transduction

Sensory organs absorb energy from a physical stimulus in the environment. Sensory receptors convert this energy into neural impulses and send them to the brain
Transduction like transmit

Selective attention

The process of discriminating between what's important and irrelevant is influenced by motivation. It can cause us to miss certain stimuli because we are focusing on a set of stimuli.

ex: Murder mystery video

Change blindness

Failing to recognize changes and objects in an environment because of your attention being elsewhere

Missing something because you’re focusing on something else.

perceptual set

how we perceive the world is a function of our experiences, culture, and biological makeup.

Society and life experience (vine boom)

Sensory adaptation

Diminished sensitivity as a consequence of constant stimulation

Car bg noise

weber’s law

to be perceived as different, two stimuli must differ by a constant minimum percentage (not a constant amount). Senses vary in their sensitivity to changes in stimuli.

Sensitivity varies, percent not amount

visual sense

Sense Organ: eye, Stimulus: Electromagnetic energy in the form of visible light (waves), Site of Transduction: Photoreceptor cells (rods and cones in the retina),

Transduced into What Energy Source: Electrochemical, Absolute Human Threshold

A candle flame from 30 miles away on a clear, dark night

auditory sense

Sense organ: ear, stimulus: Compression and expansion of molecules in the air in the form of sound waves Site of transduction: Organ of Corti in cochlea (between hair cells and basilar membrane) Transduced into what energy source: Electrochemical, Absolute human threshold: Ticking watch from 20 ft away in a quiet room

olfactory sense

Sense organ: nose, stimulus: Chemicals that are air-borne or in a substance, Site of transduction: Epithelium membrane in olfactory channel, Transduced into what energy source: Electrochemical, Absolute human threshold: Drop of perfume diffused in a small house

Gustatory Sense

Sense organ: tongue, stimulus: Chemicals mixed into saliva

Site of transduction: Taste cells within the taste buds on tongue, Transduced into what energy source: Electrochemical, Absolute human threshold: One teaspoon of sugar in 2 gallons of water

Tactile Sense

Sense organ: skin, stimulus: Touch, pressure, Site of transduction: Sensory receptors in skin, Transduced into what energy source: electrochemical, Absolute human threshold: Wing of a bee dropped on a cheek from 4/10 in away

vestibular sense

sensing mechanisms in semi-circular canals of inner ear (balance/posture)

Kinesthetic Sense

sensing mechanisms are in the muscles, tendons, and joints (motion/movement)

frequency

Loudness of sound

pitch

highness/lowness of sound

Sensorineural hearing loss

damage to the cochlea’s receptor cells, AKA “nerve deafness.” can be aided with cochlear implant

Conduction hearing loss

damage to the mechanical system that conducts sound waves to cochlea

Cochlear implant

Aid that stimulates the auditory nerve by using electrodes threaded into the cochlea

Place theory

pitch is determined by where the cochlea’s membrane is stimulated

Frequency theory

rate of nerve impulses matches the frequency of a tone

What determines a wave's hue and intensity in terms of wavelength and frequency?

wavelength and frequency determine its hue, while its amplitude determines its intensity or brightness. Short waves with high frequencies are perceived as blueish colors, and long, low-frequency wavelengths are seen as reddish hues. The brightness of a color is related to the intensity or amount of energy in a given light wave.

Young Helmholtz Trichromatic Theory

The theory is that the retina houses three specific color receptor cones that register red, green, and blue, and when stimulated together, their combined power allows the eye to register any color

Opponent-process theory

We see color through processes that work against each other. So some receptor cells might be stimulated by red but inhibited by green, while others do the opposite, and those combinations allow us to register colors.

Parallel processing

The ability to process and analyze many separate aspects of the situation at once. In the case of visual processing, this means that the brain simultaneously works on making sense of form, depth, motion and color.

pupil

The opening in the iris allows light to travel into the eye. If you shine a flashlight in an eye in a dark room. The pupils will go from dilated to pinpoints quickly.

Lens

Convex, transparent disc that focuses that light and projects it onto the retina, which makes up the inner layer of the back of the eyeball.

Rods

type of photoreceptor located in the retina that are more numerous and light-sensitive compared to cones. Can only register shades of black and white or grayscale. Distributed around the edges of the retina and are responsible for our peripheral vision. They are wired to the retina in a way that many rods may connect to a single ganglion cell, and all of them send their information to the ganglion simultaneously. Because of this they’re less adept at providing detailed images but allow them to provide information about the general shape of objects and whether they’re light or dark.

Iris

A ring of muscle tissue that surrounds the lens, the middle layer, is the iris. Distinctive colored part of the eye. It’s made of smooth muscle tissue, shaped like a flattened donut, and is between the cornea and the lens. These circular sphincter muscles contract and expand, changing the size of your pupil.

Retina

The innermost neural layer of the eye that contains millions of photoreceptors, including rods and cones, which are responsible for converting light energy into electrical signals.

Cones

type of photoreceptor located in the center of the retina. Cones are responsible for detecting fine detail and color in the visual field. They can be further categorized into red, green, and blue-sensitive types based on their responsiveness to different types of light, which corresponds to their role in color perception. Unlike rods, cones are not very light-sensitive and require bright conditions to reach their activation thresholds, more suited for tasks that involve color vision and fine details.

optic nerve

The optic nerve is a bundle of more than 1 million nerve fibers that carry visual messages. You have one connecting the back of each eye to your brain. Damage to an optic nerve can cause vision loss. The type of vision loss and how severe it is depends on where the damage occurs.

Fovea

is an area in the middle of the retina that gives the sharpest vision of any part of the retina and contains only cones.

Form Perception

 ability to visually perceive objects in the world in response to the patterns of light that they caste on our retinas.

Figure Ground Relationship

 the relationship between a subject or figure and the background against which it is set and stands out (or not), how we perceive and distinguish discrete things.

Grouping

the tendency to organize stimuli into coherent groups

Proximity

we like to group nearby figures together. 

Continuity

drawn to organize our world with attention to continuity,  perceiving smooth, continuous patterns, and often ignoring broken ones. 

Closure

We also like closure. Visually, we want to fill in gaps to create whole objects.

Depth Perception

  ability to see objects in three dimensions, including their size and how far away they are from you.

Binocular Cues

 depth cues that require the use of two eyes

Retinal Disparity

 the fact that the left and right fields of vision provide slightly different visual images when focusing on a single object. 

 Motion Perception

 the process of inferring the speed and direction of elements in a scene based on visual, vestibular and proprioceptive inputs.

 Perceptual Constancy

the perception of an object or quality as constant even though our sensation of the object changes.