Unit 3: Sense and Perception

sensation

sensation

The process of detecting physical energy from the environment through our senses (like seeing, hearing, or touching)

perception

The way we interpret and make sense of the sensations we receive, allowing us to understand what we are experiencing.

bottom-up processing

Starting from the basics; building up an understanding from small sensory details to form a full picture. No prior knowledge is used.

top-down processing

information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

inattentional blindness

failing to see visible objects when our attention is directed elsewhere

change blindness

failing to notice changes in the environment

transduction

conversion of one form of energy into another. In sensation, the transforming of stimulus energies, such as sights, sounds, and smells, into neutral impulses our brain can interpret

psychophysics

The study of how physical stimuli (like light and sound) relate to our psychological experiences (like brightness and loudness)

absolute threshold

the minimum stimulation needed to detect a particular stimulus 50 percent of the time

signal detection theory

a theory predicting how and when we detect the presence of a faint stimulus amid background stimulation. Assumes that there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness

subliminal perception

below one’s absolute threshold for conscious awareness (detect less than 50% of the time)

priming

the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response (if you see the word yellow and then shown a list of words, you most likely would choose banana bc they are associated)

difference threshold

the minimum difference between two stimuli required for detection 50 percent of the time. We experience the difference threshold as a just noticeable difference

Weber’s law

to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than constant amount)

sensory adaptation

diminished sensitivity as a consequence of constant stimulation

perceptual set

a mental tendency/assumption to perceive one thing and not another

Hit/Miss

In signal detection theory, a "hit" occurs when a stimulus is present and correctly detected, while a "miss" happens when the stimulus is present but not detected.

false alarm

When you think you detect a stimulus that isn’t actually present.

Correct rejection

When no stimulus is present, and you correctly don’t detect anything

Just Noticeable Difference (JND)

the smallest change in a stimulus that you can detect (slight inc in volume)

Receptor Cells

specialized cells that respond to sensory stimuli and send signals to the brain

Receptive field

An area on your skin where touch receptor cells detect pressure

Sensory Coding

the process by which sensory receptors convert physical stimuli into neutral signals that the brain can understand

Visual Sensation

the initial detection of light and color by the eyes before it is interpreted by the brain

Distal stimulus

the actual object or event in the outside world that you’re looking at or sensing

proximal stimulus

The image of the object formed on the sensory receptors (like the retina) when you perceive something

Accomodation

the process by which the eye changes lens shape to focus near or far objects on the retina

Optic Chiasm

The point in the brain where the optic nerves from each eye meet and cross over to the opposite side of the brain

Serial Processing

Processing one piece of information at a time, step-by-step

Parallel Processing

The brain's ability to process multiple aspects of a stimulus simultaneously, such as color, depth, motion, and shape (driving a car); more automatic and subconscious

Convergence

A binocular cue where the eyes move inward to focus on a close object, providing depth perception.

Young-Helmholtz Theory (Trichromatic Theory)

the retina has three types of color receptors (red-long cones, green-medium cones, blue-short cones) that combine to form other colors

Opponent Process Theory

color vision is enabled by opposing pairs of colors (red-green, blue-yellow, black-white) where some neurons are stimulated by one color and inhibited by its opposite. (see green after starring at red for a while)

Place Theory

in hearing, the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated

• high-pitched sound = vibration is detected at the base of the cochlea.

• the deeper tones = vibrations toward the apex of the cochlea

Frequency Theory

in hearing—rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch (If the frequency of the sound is 50 Hz, the nerve fibers would fire at approximately 50 times per second, providing the brain with the information necessary to identify the pitch)

Conductive Deafness

Caused by problems in the ear canal or middle ear (ear infections)(mechanical system); hearing aids help

Sensorineural Deafness

caused by damage to the inner ear (cochlea’s receptor cells) or auditory nerve (aging or loudness); hearing aids don’t help

olfaction

sense of smell

Cutaneous Receptors

nerve receptors in the skin that respond to touch, pressure, pain, and temperature

Tactile Receptor

A type of cutaneous receptor specifically for detecting touch and texture.

Cold fibers

respond to cold stimuli

Warm fibers

respond to warm stimuli

Vestibular Sense

tells you if you are physically upright without eyesight—balance; relies upon the semi circular canals located in your ears

Kinesthesis

the sense that detects body position and movement; perceives the extent, direction, or weight of movement. (know where your arms are when your eyes are closed; dribble basketball w/o looking)

Habitutation

involve a more active learning process; decreased response to a repeated stimulus over time (ignoring); cognitive level

Selective Attention

capacity to react to certain stimuli selectively when several occur simultaneously; choosing what to pay attention to

Cocktail Party Phenomenon

being able to focus one’s auditory attention on a particular stimulus while filtering out a range of other stimuli (listen to one voice among many); more subconscious

Filter Theories

attention operates as a filter that allows certain stimuli to be processed while block out others

Divided Attention

the ability to respond to multiple stimuli simultaneously; multi-tasking; often results in decrease in performance

Gustav Fechner

coined the term psychophysics; making connection between matter and mind; public and private

Ernest Webner

used signal detection theory in real-world situations

Gestalt

principles used to make order out of perceptions so that we see things as connected and not just random bits of info

Gestalt Proximity

objects close together will be viewed together visually

Gestalt Closure

the brain is good at filling in gaps to create a whole

Gestalt Similarity

two items that share attributes will be visually grouped together

Gestalt Continuity

a line will always appear to continue traveling in the same way

Gestalt Figure and Ground

sometimes, the blank space is just as important as the filled space

Binocular Depth Cues

depth cues, that depend on the use of two eyes; rely on the slightly different images that each eye receives due to their separation.

Law of Pragnanz

we tend to perceive things in the simplest, most stable form

Phi Phenomenon

an illusion of movement created when two or more adjacent lights blink on and off in quick succession

Stroboscopic effect

the illusion of movement when a series of static images or lights are shown in quick succession (in film and animation)

Intensity

amplitude; amount of energy in a light wave is determined by height of a wave (higher wave=more intense light)

Perception of Color

our minds perceive the color of light of the color being rejected

Pupil

adjustable opening in the center of the eye through which light enters

Iris

a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening; adjusts its size in response to light levels in the environment. When it's bright, the pupil becomes smaller (constricts) to limit the amount of light entering the eye. In low light, the pupil becomes larger (dilates) to see better in dim conditions

Lens

transparent structure behind pupil that changes shape to focus images on the retina (focus light onto the retina, about 1/3, does fine tuning)

Cornea

transparent outer covering of the eye (responsible for about two-thirds (2/3) of the eye's ability to focus light)

Retina

contains visual sensory receptors (photoreceptors in it capture light and convert it into electrical signals)

Fovea (Retina)

point of central focus; contains most of eye’s cones (color); visual acuity (see finest details); center part of retina

Optic Nerve

pathway to the brain’s visual cortex

Blind spot

occurs at the location in the retina, where the visual cortex exits to the brain, there are no receptors there; spot in the retina where the optic nerve connects 

Nearsighted (Myopia)

eye is elongated; nearby objects are seen more clearly[lens causes light to focus too soon (in front of the retina)]

Farsighted (hyperopia)

eyes are shortened; faraway objects are seen more clearly [lens (or eye shape) causes light to focus too late (behind the retina)]

Photoreceptor Cells: Rods and Cones (Retina)

1. peripheral retina; detect black, white and gray; twilight or low light

2. near center of retina; fine detail and color vision; daylight or well-lit conditions

Bipolar (retina)

receive messages from photoreceptor cells (rods and cones) and transmit to ganglion

Ganglion (retina)

Its axons form optic nerve; neurons in the retina that receive signals from bipolar cells and send visual information to the brain’s visual cortex via the optic nerve.

Blindsight

you can see something but can't consciously recognize or be aware (perceive) of it.

Feature Detector

cells in the visual cortex of the brain that respond selectively to specific features of complex stimuli (edges, angles, length, movement)

David Hubel and Torsten Wiesel

discovered feature detectors in visual system

Colors

the way our brain interprets different wavelengths of light, with each wavelength corresponding to a different color in the visible spectrum; visible/optical light

Visible/Optical Light

only a small sample of total electromagnetic spectrum; most light is invisible to our eyes

Wavelength

• distance from the peak of one light wave to the next; distance determines hue (color) of the light we perceive

• short WL=high freq (blue, high pitched, high energy & precision) (X-ray)

• long WL=low freq (red, low pitched, penetration, long distance) (radio waves)

Intensity

amplitude, brightness; higher wave=more intense light

Saturation

more= more intense or pure it looks.

less=appears more washed out or grayish.

Monochromats

zero (daylight uncomfortable; no colors) or only one type of functioning cone type (can’t discriminate colors; only shades of red/blue/green) and respond to light like a black/white film

Dichromats

only one malfunctioning cone type; 2 ok cones

Apophenia

experience of seeing meaningful patterns or connections in random/meaningless data (seeing a face on a car based on car parts)

Frequency (pitch)

Hz; number of complete wavelengths that pass through a point at a given time determines pitch; long wl=low freq; short wl=high freq

Intensity (loudness)

volume, measured in decibels

Olfactory nerve

transmits odors to the limbic system of the brain

Unique Olfactory system

bypasses the thalamus; impulses from nerve fibers from olfactory bulb connect to the brain at the amygdala and then to hippocampus

Gustation

sweetness, sourness, saltiness, bitterness (naturally poisonous), umani=savory

Touch

pressure, temp, pain; some areas are more sensitive—more nerve endings

Gate Theory

only a small amount of info can be processed by the nervous system at a time; flooding brain with other stimulus blocks some pain messages (sneeze while getting a shot)

nociceptors

detects pain—hot nerves and cold nerves

proprioception

includes both static (position) and dynamic (movement) awareness of your body.

Monocular Cues (depth perception)

needs only one eye to perceive depth; perspective, clearness, shadow, overlapping, gradient texture, motion parallax (objects that are closer, appear to move faster than objects that are far away)

Retinal disparity

binocular disparity; images from 2 eyes differ; closer the object, the larger the disparity (finger in front of face)

Perceptual Constancies

perceiving objects as unchanging even as light and retinal images change (4 types)

Color Constancy

tendency to perceive objects as keeping their color even though different light changes the appearance of their color