APP Unit 3

sensation and perception

Sensation

bringing in sensory stimuli from the environment to the brain

Perception

Organizing & interpreting sensory info

Transduction

Converting an environmental energy into a neural impulse

Absolute Threshold

the minimum amount of energy needed to detect the presence of a stimulus (50% of the time)

Just noticeable difference (JND)(AKA difference threshold)

the minimum amount of energy needed to detect a change in a stimulus or the difference between two stimuli (50% of the time)

Weber’s Law (related to JDN)

JND is a fixed proportion of the intesiry of the stimulus

The greater initial intensity of a stimulus the more it is going to take to notice

Sensory adaptation

decline in sensitivity to stimuli that are presented at a constant level (our sensory neurons become less responsive)

Sensory Interaction

Occurs when one sense impacts another (taste and smell)

Synesthesia

Cross-talk of the senses   (KIKI- Sharp object)

Amplitude

Brightness/intensity

Wavelength

color/hue

Short Wavelengths

blues

Long Wavelengths

reds

Visual Process

Light wave - cornea - iris + pupil - lens - retina - photoreceptors - bipolar cells - ganglion - forms the optic nerve - optic disk - thalamus - occipital lobe

Accomodation

the ability of the lens to bend light rays in order to focus the image (based on the objects location on the retina)

Nearsightedness

Occurs when the lens bends too much causes the image to fall in front of the retina

Farsightedness

occurs when the lens doesn’t bend enough causes the image to fall in behind the retina

Photoreceptors

Sensory receptors for vision ~ responsible for transduction

Cones

Color vision; helps us to see in the daytime/bright loghting; located in the center of the retina

Fovea

Center of the retina, highest concentration of cones; greatest visual activity (detail)

Rods

Detect black white and gray sensitive to movement more sensitive in dim lighting; located on the outher edge of the retina (peripheral vision)

Bipolar cells

Receive visual signals from photoreceptors (rods & cones) help to see contrast and edges

Ganglion Cells

Signals sent from bipolar cells; axons of ganglion cells bundle together to form the optic nerve

Optic nerve and Optic disk

The optic nerve leaves the eye at the optic disk

Blindspot

Where the optic nerve leaves the eye there are no rods and cones, which creates a blind spot

Feature detectors

Specialized cells that respond to specific features of more complex stimuli (edges, lines, angles)

Parallel Processing

Processing visual information is done simultaneously (as opposed to serial processing)

Blindsight

A condition in which a person can respon to a visual stimulus without consciously experiencing it

Prosopagnosia (face blindness)

the inability to recognize human faces

Visual agnosia

the inability to recognize objects

Young-Helmholtz Trichromatic Theory

there are 3 types of receptors (cones) with different sensitivities to different wavelengths that can create all colors: red green blue

Color Blindness

Lack one of the three (or more in rare cases two) types of cones

(supports the Trichromatic theory of color vision)

Dichromatism

Only 2 cone types are functional

Monochromatism

Only one type of cone is functional

Opponent Process theory

Color perception is determined by the activity of 3 opponent systems: yellow-blue red-green black-white

Occurs in the ganglion cells

Afterimages

an image that continues to appear in the eyes after a period of exposure to the original image

Supports the opponent process theory of color vision

figure-ground

figure-the object

Ground- the background or surroundings in which the object occurs

Closure

filling in the gaps to perceive a completed image

Proximity

Objects close together are grouped together

Similarity

grouping based on shared characteristics

Perceptual constancies

Pereving object as unchanging (having consistent color,size, shaoe, brightness, ect.) even as illumination and retinal images change

Visual Cliff (what is it and what was learned)

Apparatus used to to test depth perception in infants

Depth perception is largely innate

Binocular depth cues

Retinal (binocular) disparity'

depth perception guided by the different images seen by each eye

Convergence

sensing the eyes converging (turning inward) as they focus on closer objects

Linear perspective (monocular depth cues)

parallel lines appear to converge in the distance

Relative Size

Closer objects appear larger that far away objects

Relative Clarity

Objects in the distance appear less clear/ more blurry; objects that are closer appear clear/sharp

Texture Gradient

Objects far away appear to have less detail than objects close up

Interposition

Objects that obstruct/block the view of of another object are perceived as closer

Phi Phenomenon/Stroboscopic motion

an illusion of a movement (as in a motion picture) experienced when viewing a rapid series of still images

Looming

As an image expands into our retina we perceive it as approaching us

Selective attention

the ability to focus your conscious awareness (attention) on a particular stimulus while ignoring others

Cocktail Party Effect

In a crowded environment, we can completely block out others and focus on 1 thing but when something relevant to you is said your attention shifts

Inattentional blindness & change blindness

Failure to see visible objects or events (or a change in one’s environment) because one’s attention is focused elsewhere (or we’ve stopped processing due to top-down processing)

Ex. Folding laundry; Basketball Passes

Bottom-up processing

using details/features.characteristics of a stimulus to guide perception (understand our world) external focus

Ex. Istlef Awlyas

Top-down Processing

Using Schemas, prior experiences, expectations or context to guide perception (understand our world) (internal focus) we make a quick assumptions using little evidence

Ex.

Schemas

Mental represensations of people, objects, events, ideas, etc.

created by experience (visual, auditory, emotion etc)*

Ex. Boo calls Sully Kitty because that's how she has pictured a cat

Perceptual set & Priming

The tendency to perceive a stimulus in a particular way (guided by prior experiences, expectations, surroundings/context, current mood, etc.)

Ex. Scary Mary

Amplitude

Loudness/ Intensity

Frequency

Pitch

Timbre

Purity

Auditory Process

Perceiving loudness

The brain interprets loudness from the number of activate hair cells

Perceiving Location

Based on differences in the timing & intensity each sound wave enters the ear

Place theory

Perception of pitch corresponds to the vibration of different portions, or locations/ places along the basilar membrane

Best explains the High frequency sounds

Frequency Theory

perception of pitch corresponds to the firing rate, or frequency, at which the auditory nerve vibrates

best explains low frequency sounds

Volley Theory

Groups of neurons fire slightly out of phase with one another

So that when combined a particular pitch is perceived

Conduction Deafness

problems/damage to the three little bones tympanic membrane

(may be corrected with hearing aid)

Sensorineural deafness

problems/damge to the cilia (hair cells) or auditory nerve

(maay be corrected with a cochlear or auditory nerve implant)

Taste Buds (papillae)

papillae/taste buds contain sensory receptors for taste

6 taste: sweet sour bitter salty umami (savory meaty taste) & oleogustus (unique taste of fat

taste buds are most sensitive to 1 or 2 taste and weak to others

Flavor

flavor is a combination of what two senses

taste & smell (sensory interaction)

Supertasters. Medium tasters & nontasters

Supertasters have more buds than others

Olfaction (+sensory receptors)

Cilia (hair cells) in the nose

Olfactory blub

cilia in the nose sends signals to the olfactory bulb in the brain

*doesn’t go through thalamus first 

(part of the limbic system)

Pheromones

Odor chemicals that shape the behavior/physiology of animals

Somatosensory system (touch)

4 types of touch receptors? Pain, Pressure, Warm. Cold

Hot= warm + cold wetness= cold+pressure

Understanding Pain

It’s important to feel pain so the body gets the sensation it needs for the body to develop and so the brain can be stimulated

Gate Control Theory

Pain can be blocked at the spinal cord Other sensory information aside from the pain signals can take over the pain pathway

Phantom Limb Sensations

When lacking the normal sensory imput from a missing limb, the brain misinterprets and amplifies spontaneous but irrelevant CNS activity

Vestibular sense (balance)

Sensory System providing information about spatial prientation (position of head & body in space) as well as our sense of balance

Ex. Visual system & inner ear semicircular canals & vestibular sacs play large role

Kinesthesia

Sensory system providing information about where parts of your body are in relationship to each other, providing us with out sense of coordination

Ex. Ability to sense the movement of muscles tendons and joints