AP Psych Unit 1 - Sensation

Section Three of AP Psych Unit 1 - Biological Bases of Behavior

transduction

sensory signals being transformed into neural impulses, which travel to the thalamus and then different cortices (except for smell)

sensory adaptation

decreasing responsiveness to stimuli due to constant stimulation (forget you are wearing socks after a while)

sensory habituation

our perception of senses is partially due to how focused we are on them.

cocktail party effect

We can voluntarily attend to stimuli in order to perceive them, as you are doing right now, but paying attention can also be involuntary. If you are talking with a friend and someone across the room says your name, your attention will probably involuntarily switch across the room.

synesthesia

a phenomenon some people experience in which the activation of one sense, like seeing a color, activates another sense, like hearing a specific sound, or vice versa.

Prosopagnosia

the inability to recognize faces.

wavelengths

wavelengths longer than visible light are infrared waves, microwaves, and radio waves. Wavelengths shorter than visible light are UV waves, X-rays, and gamma waves.

accommodation

light enters the pupil and is focused by the lens, which changes shape to focus light on the retina

transduction (eye)

translation of oncoming stimuli into neural signals. Occurs when light activates the neurons in the retina

photoreceptors

include rods and cones. cones are activated by color, while rods respond to black and white. Rods outnumber cones 20 to 1. Cones are concentrated towards the center of the retina.

Fovea

Located at the center of the retina, contains the highest concentration of cones. If you focus on something, you are focusing the light onto your fovea, and you will see it in color. Your peripheral vision, especially at the extremes, relies on rods and is mostly in black and white. Your peripheral vision may seem to be full color, but controlled experiments prove otherwise.

process of transduction

If enough rods and cones fire in an area of the retina, they active the next layer of bipolar cells. If enough bipolar cells fire, the next layer of cells, ganglion cells, is activated. There are more rods and cones than bipolar cells, and there are more bipolar cells than ganglion cells. The axons of the ganglion cells make up the optic nerve that sends impulses to a specific region in the thalamus called the lateral geniculate nucleus (LGN). From there, the messages are sent to the visual cortices located in the occipital lobes in the brain.

blind spot

The spot where the optic nerve leaves the retina has no rods or cones

trichromatic theory

Hypothesizes that we have three types of cones and each type detects a different primary color of light: blue, red, or green. These cones are activated in different combinations to produce all colors. This theory cannot explain afterimages, or color blindness.

Afterimages

If you stare for a while and then look at a white or blank space, you will see a negative color afterimage. If you stare at green, the afterimage will be red, while the afterimage of yellow is blue.

Dichromatism

Form of color blindness. Individuals with dichromatism cannot see either red/green shades or blue/yellow shades.

Monochromatism

Form of color blindness. Causes people to only see shades of grey.

Opponent-process theory

States that sensory receptors arranged in the retina come in pairs: red/green, yellow/blue, black/white. If one sensor is stimulated, its pair is inhibited from firing. Explains afterimages. If your stare at red for a while, you fatigue the sensors for red. Then when you look at a white page, the red sensors won’t be able to fire as much as the green ones so you will see a green afterimage. Also explains color blindness. If color sensors come in pairs and an individual is missing a pair, they should have difficulty seeing those hues.

amplitude

height of the wave and determines the loudness of the sound, which is measured in decibels.

frequency

length of the waves and determines pitch, which is measured in megahertz. High pitched sounds have high frequencies, and their waves are densely packed together. Low pitched sounds have low frequencies, and their waves are spaced apart.

process of sound travelling

collected in outer ear/pinna, travels through ear/auditory canal until it reaches the tympanic membrane (eardrum), which vibrates when sound waves hit it. The waves then travel through the three ossicles (stirrup/stapes, anvil/incus, hammer/malleus). The ossicles amplify the sound towards the oval window, which is connected to the cochlea. As the oval window vibrates, the fluid in the cochlea moves, which cause the hair cells in the cochlea to move, and transduction occurs.

sound localization

The fact that humans have two ears means that you can determine approximately where a sound originated. This is because when information from our ears reach the brain, our auditory cortices notes whether the sound was louder in one ear or another.

Place theory

holds that the hair cells in the cochlea respond to different frequencies of sound based on where they are located in the cochlea. Some bend in response to high pitches and some to low. We sense pitch because the hair cells move in different places in the cochlea.

Frequency theory

research demonstrates that place theory accurately describes how hair cells sense the upper range of pitches but not the lower tones. Lower tones are sensed by the rate at which cells fire. Frequency theory states that we sense pitch because the hair cells fire at different rates (frequencies) in the cochlea.

Conduction deafness

occurs when something goes wrong with the system of conducting the sound to the cochlea (in the ear canal, eardrum, hammer/anvil/stirrup, or oval window). For example, a patient has a medical condition that is causing her stirrup to deteriorate slowly. Eventually, they will need surgery to replace that bone to hear well.

Nerve deafness/sensorineural deafness

occurs when the hair cells in the cochlea are damaged, usually by loud noise. If you have ever been to a concert, football game, or other event loud enough to leave your ears ringing, chances are you came close to or did cause permanent damage to your hearing.

Gate control theory

explains that some pain messages have a higher priority than others. When a higher-priority message is sent to the brain, the gate swings open for it and swings shut for a lower priority message, which we will not feel. When you scratch an itch, the gate swings open for your high-intensity scratching and shuts for the low-intensity itching, and you stop the itching for a short period of time. (Do not worry, though, the itching usually starts again soon!) Endorphins, or pain-killing chemicals in the body, also swing the gate shut. Natural endorphins in the brain, which are chemically similar to opiates like morphine, control pain.

taste receptors

located on papillae, which are the bumps you can see on your tongue. Taste buds are located all over the tongue and some parts of the inside of the cheeks and roof of the mouth. Humans sense five different types of tastes: sweet, salty, sour, bitter, umami (savory or meaty taste), and oleogustus (taste of fat). Some taste buds respond more intensely to a specific taste and more weakly to others. The more densely packed the taste buds, the more chemicals that are absorbed and the more intensely the food is tasted. Supertasters have densely packed papillae and taste food intensely. The density of these bumps on the tongue is a trait controlled by genetic predispositions. If the taste buds are spread apart, you are probably a nontaster (or medium taster). What we think of as the flavor of food is actually a combination of taste and smell.

Smell/olfaction

Receptor cells in the nose are linked to the olfactory bulb, gathers the messages from the olfactory receptor cells and and sends this information to the brain. The impulses from all, except smell, go through the thalamus first before being sent to the cortex. However, information from our sense of smell goes directly to the amygdala (emotional impulses) and then to the hippocampus (memory). This direct connection to the limbic system may explain why smell is such a powerful trigger for memories.

Vestibular sense

tells us how our body is oriented in space. Three fluid-filled semicircular canals in the inner ear give the brain feedback about body orientation. When the position of your head changes, the fluid moves in the canals, causing sensors in the canals to move. The movement of these hair cells (similar to the hair cells in the cochlea in our ear) activate neurons, and their impulses go to the brain.

kinesthetic sense

gives us feedback about the position and orientation of specific body parts. Receptors in our muscles and joints send information to our brain about our limbs. This information, combined with visual feedback, lets us keep track of our body. You could probably reach down with one finger and touch your kneecap with a high degree of accuracy because your kinesthetic sense provides information about where your finger is in relation to your kneecap.