Module 4: Sensation and Perception Psychology

Sensation

raw physical energy taken in through our senses

Perception

How your brain analyzes, interprets, or integrates information that receives from the different senses

Transduction

when the stimulus is converted to neural impulses

Coding

different messages will be sent to different parts of the brain

EX: information from our eyes will be sent to the thalamus then to the occipital lobe

Sensory Reduction

we naturally filter all the sensory information that comes forward

Synesthesia

a rare condition where some individuals get the mixing of their senses

EX: when they taste something, they have a sound that they hear that is connected to that certain taste

EX: some people connect letters with color (may see the letter R as yellow)

Absolute Threshold

The minimum intensity that is needed for us to be able to notice that a stimulus is present 50% of the time

Noise

any background stimulus that interferes with your perception of another stimulus

“The smallest change in intensity”

Difference Threshold

The minimum intensity that needs to be present to be able to determine that a change has occurred 50% of the time

Weber’s Law: “JND” Just Noticeable Difference

your ability to pick up a stimulus will depend on the original intensity

Signal Detection Theory and its factors:

factors that influence one’s ability to detect/pick up a stimuli/stimulus

EX: intensity - if you have a hearing test, they're trying to find your absolute threshold for sound at different frequencies

Sensory Adapation

exposure to repeated/constant sensory stimuli decreases our response and ability to detect the stimuli

EX: walking into a freshly painted room - you’re first bombarded with the smell of paint. But within a few minutes, you don’t even detect the smell anymore (adapting to that stimulus)

how does the eye function to convert electromagnetic radiation waves into neural impulses for the brain to interpret?

electromagnetic radiation waves are brought into the eye through stimulation. First hitting the lens. Transduction occurs and converts the electromagnetic radiation waves into neural impulses at the retina level. Sensation occurs. Then those signals travel through the optic nerve to the brain for interpretation.

Visible spectrum colors

ROYGBIV

Cornea

transparent protective covering of the eye

Iris/Pupil

regulates the amount of light entering the eye

Lens

A clear membrane that bends the light waves to try to focus the image on the retina (back of the eye)

electromagnetic radiation waves travel here

Accommodation

The lens (muscles) change shape to help focus an image

EX: if you’re looking at something far away your lens expands or becomes thinner to help focus. If you’re looking at something up close, your lens plumps up to focus

Photoreceptor cells

Rods and Cones

Rods

allow us to see black and white, peripheral vision, and night vision

• is found off the sides of the fovea

• When looking at something at night, it’s better to look at it slightly to the side and not directly at it so that these can be stimulated

Cones

allow us to find focus and to see color

Fovea

where an abundance of cones is found

• An image falls on this so we can see it most clearly

Optic Nerve

where neural impulses leave the back of the eye

Blind Spot

where the optic nerve leaves the back of the eye

• If an image falls on here, you do not see it

• Each eye has one of these because one eye compensates for the other eye’s ______. the brain fills in what is missing.

Optic Chiasm

Each eye sends information off to the appropriate place in the brain

Thalamus

When neural impulses cross over, information is sent here and to the appropriate lobe in the brain. Then passes that information to the left occipital lobe

Feature Detection Theory

There are specialized brain cells that respond to specific stimuli

EX: some cells respond to perpendicular lines, horizontal lines, curved lines, movement, etc.

Myopia

Nearsighted: when a person can see clearly up close but has difficulty seeing things far away

• Eyeball is elongated

• When looking at a picture, the picture doesn’t get focused on the retina but gets focused before the retina

Hyperopia

Farsighted: people can see clearly far away, but have difficulty seeing up close

• Eyeball is too short

• When looking at a person, the person gets focused beyond the retina

Astigmatism

when the cornea and the lens are not symmetrical 

EX: cornea football-shaped instead of basketball

Presbyopia

when you get older, you have a hard time seeing things

• Reading glasses can help

How do people see in color?

Cones which are sensitive to different wavelengths of light allow us to do this

Trichromatic Theory of Color Vision

includes 3 types of cones that respond to: Blue, Red, and Green

• Ability to see color is dependent upon the strength that each cone is stimulated

Opponent Process Theory of Color Vision

Receptor cells linked in pairs that work in opposition to one another/3 color systems that work in opposition to eachother

• Red-green

• Yellow-blue

• White-black

• EX: If blue is stimulated, yellow is shut down

Afterimage

when one set of cones tires, and the other will come through

EX: American flag image:

green, yellow, and black showed red white, and blue

Trichromats

someone who sees color

Monochromats

someone who only sees black and white

Dichromats

someone who has some form of color limitation

How do we hear sound?

movement of ear molecules produced by sound enters the ear through the pinna. Then travels down the auditory canal to the eardrum. The vibration of the ear molecules causes the eardrum to vibrate which in return will cause the 3 ossicles in the middle ear to vibrate. These vibrations are picked up by the oval window which is the opening into the inner ear where we find the cochlea. The cochlea is a closed, snail-shaped device, that has fluid, basilar membrane, and hair cells. The vibrations against the cochlea cause pulsations within the cochlea which cause the hair cells to move. It is the movement of the hair cells that produce the neural impulses that leave through the auditory nerve, travel to the thalamus, and then to the temporal lobe to be processed.

Sound/Audition

The movement of ear molecules caused by the vibration of an object

Frequency

Aka Pitch: how we measure sound

• The number of waves per second, measured in hertz = cycles/sec

• High-frequency sound waves enter at very rapid rates

• Low-frequency sound waves enter at a slower rate

Intensity

Aka Loudness: measured in decibels

EX: If a sound originates from your right side, it makes sense that the right ear will receive a sound at a higher _____ or slightly higher than your left because your head acts as a sound absorber

Outer ear

• contains the pinna: (part of the ear that we can see) acts like a funnel to bring sound into the ear

• Vibration of ear molecules enter the auditory canal and helps us identify where sound originates from (sound localization/timing and loudness)

• Eardrum = (tympanic membrane) delicate membrane that vibrates with the sound waves. 

• Helps transmit these sound waves from the outer ear to the middle ear

• Separates outer and middle ear

Middle Ear

• Contains 3 ossicles/bones:

• Malleus - known as the hammer

• Incus - known as the anvil

• Stapes - known as the serial?

• When the eardrum vibrates as a result of those ear molecules, it causes these 3 bones to vibrate and transmit these vibrations to the inner ear

• Amplifies sound

Inner Ear

• Vibrations of the ossicles in the middle ear stimulate the oval window

• Those vibrations pulsate the oval window

• Cochlea (snail-shaped thing): a closed system that contains fluid, basilar membrane, and hair cells

• connected to the oval window

• When vibrations/pulsations occur within the cochlea, due to the vibrations on the oval window, the hair cells move

• Hair cells: movement of the hair cells on the basilar membrane that produces the neural impulses needed to send the information to the brain

• Hair cell level that sound waves get converted to neural impulses

• Hair cells closer to the oval window = low frequencies

• Hair cells farther from the oval window = high frequencies

• Neural impulses are then sent to the Auditory Nerve to the Thalamus (relay station), which then forward those neural impulses to the Temporal Lobe where sound can be processed

Place Theory

explains that there are different places on the basilar membrane that respond to different frequencies

• If we unfold the cochlea, the area closest to the oval window is sensitive to high frequency sounds, and the area away from that opening is sensitive to lower frequency sounds

Conduction hearing loss

(poor transfer of sound) anything that gets in the way of conducting the vibrations to the inner ear

• EX: Wax build-up, fluid in middle ear, middle ear infections, damage to 3 ossicles (bones)

Sensorineural hearing loss

when there is a problem within the cochlea or the nerve

• Can be caused by the destruction of the hair cells on the basilar membrane or the auditory nerve

• If the nerve is no longer functioning, there’s nothing that can be done

• If the nerve is functioning, hearing aids or a cochlear implant can help

Stimulation hearing loss

due to a hobby, career, job, you are exposed to loud sounds over time so you will lose the ability to hear sound at those frequencies

• EX: Someone who hunts can lose the frequency of the sound of a gun firing if they are continually exposed to that over time

Cochlear implant

can be used when a person’s hearing loss is significant enough that it warrants intervention and does not respond appropriately to hearing aids.

• A device is threaded through the cochlea and the device now acts like the hair cells stimulating the nerve

• Must have an intact auditory nerve in order for it to work

• They replace hair cells

Olfaction

Aka Smell

• Stimulates the olfactory bulb, messages get sent to the brain for us to determine smell.

• Epithelial _____ cells, convert to neural impulses, and send messages to the brain

Gustation

Aka Taste

• Papillae = bumps on your tongue

• Pits in the papillary = taste buds

• Chemical reactions are sent to the brain to be processed

  3 categories

• Supertasters = have a large number of taste buds, and don’t need much sugar or additives to be satisfied

• Average Tasters

• Nontasters = have a lower-than-average number of taste buds, and need added sugar and additives to be satisfied. They seek out sweeter, fattier foods in order to be satisfied.

• Our taste buds are replenished every 7-10 days

Anosmia

the inability to smell

• caused by having a cold, can be due to an injury, or you are born with this condition

• people with this often refer to the consistency of food in order to help determine taste because there’s a connection between taste and smell

Temporal (Frequency) Theory

(helps explain pitch)

• In hearing, the theory that the rate of nerve impulses traveling up to the auditory nerve matches the frequency of a tone, enabling us to sense its pitch

• Vibration of the basilar membrane matches the frequency of the sound wave

• The brain can then read the pitch from the frequency of the neural impulses

How is the sensation of pain sent to the brain?

The receptors on our skin that allow us to perceive touch, pressure, and pain are processed in the parietal lobe in the brain

Gate Control Theory of Pain

A mechanism in the spinal cord where in certain things will open the gate and allow the message of pain to be sent to the brain where other things will close the gate

Substance P

(Prostaglandins) When cells are injured we refer to it as Prostaglandins

• moves white blood cells and blood flow to the area to help heal

• is subjective: what one person may think is painless, the other might think its painful

• We take medications to alleviate pain which blocks the production of ______

What can influence people’s perception of pain?

• Being anxious

• Being in control, or feeling like you're in control

• Distraction EX: child falls, gets a cut, and is crying, you can’t get them to calm down so you offer a popsicle to them, which distracts them and gets them to calm down

• Stimulations

Figure-Ground Organization

Believed that the brain perceives information as there is a background and a figure which resides in front of the background

• EX: looking at a TV, the TV would be the figure and the ground would be the wall behind it

Reversible (impossible) figure

When we are unable to identify what the figure is and what the ground is, our perception will go back and forth

Closure

Gestalt’s Law of Organization: When the brain tends to ignore breaks and concentrates on the perceived whole

• No lines to close the perceived space but our mind puts it together

Proximity/Nearness

Gestalt’s Law of Organization: elements that are placed close together we perceive as going together

Similarity

Gestalt’s Law of Organization: elements that are similar to each other we tend to automatically group

Simplicity

Gestalt’s Law of Organization: We tend to see things in the most simple and straightforward manner (the most simple way to do things)

Monocular cues depth perception

we use 1 eye to help us perceive depth

• Accommodation: with 1 eye our lens can accommodate to help us to see clearly

• Interposition: the ability to see what image is infront of another image (TV & wall example)

• Linear Perspective: when you look into the distance, it appears as though train tracks come together 

Binocular cues depth perception

we use 2 eyes to help us perceive depth

• Convergence: what we tend to use up close

• Retinal Disparity: what we tend to use far away (looks at the distance between images)

Size Constancy

Perceived size of an object/image does not change/grow even though the image reflected on the retina does

Shape Constancy

Perceived shape of an object/image does not change/grow even though the image reflected on the retina does

Perceptual Set

When prior exposure, experiences, and expectations influence how we interpret information/stimuli

• Can be influenced by: context, past experiences, motivation, emotional state, and cultural factors

Top-Down Processing

when we use past exposure or experiences

• Using models, ideas, and expectations to interpret sensory information

• showing the picture first, then completing the puzzle (you have something to work from when putting the puzzle together

Bottom-Up Processing

when we take information and put it together

• Taking sensory information and then assembling and integrating it

• EX: completing the puzzle without seeing what it’s going to look like in the end