Chapter 5 Sensation and Perception - Group 2

Gestalt Rules

Developed by a group of researchers from the early 20th century who described the principles that govern how we perceive groups of objects. (e.g., proximity, similarity, continuity, closure). \n Based on the observation that we normally perceive images as groups, not as isolated elements. \n This process is believed to be innate and inevitable.

Figure-Ground

The organization of the visual field into objects (the figures) that stand out from their surroundings (the ground).

Grouping

The perceptual tendency to organize stimuli into coherent groups

Depth Perception

The ability to see objects in three dimensions although the images that strike the retina are two dimensional; allows us to judge distance.

Visual Cliff

A laboratory device for testing depth perception in infants and young animals.

Depth Cues

Researchers divide the cues that we use the perceive depth into two categories: \n Monocular cues - Depth cues that do not depend on having two eyes (e.g., linear perspective, interposition, shading, and texture gradient). \n Binocular cues - Cues that depend on having two eyes (e.g., retinal disparity and convergence).

Retinal Disparity

A binocular cue for perceiving depth by comparing images from the retinas in the two eyes, the brain computes distance—the greater the disparity (difference) between the two images, the closer the object.

Convergence

A binocular cue for perceiving depth; the extent to which the eyes converge inward when looking at an object.

Phi Phenomenon

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

Perceptual Constancy

Perceiving objects as unchanging (having consistent color, brightness, shape, and size) even as illumination and retinal images change. \n Every object we see changes minutely from moment to moment due to our changing angle of vision, variations in light, and so on. \n This is our ability to maintain a constant perception of an object despite these changes.

Size Constancy

Objects closer to our eyes will produce bigger images on our retinas, but we take distance into account in our estimations of size. \n We keep a constant size in mind for an object (if we are familiar with the typical size of the object) and know that it does not grow or shrink in size as it moves closer or farther away.

Shape Constancy

Objects viewed from different angles will produce different shapes on our retinas, but we know the shape of an object remains constant. \n For example, the top of a coffee mug viewed from a certain angle will produce an elliptical image on our retinas, but we know the top is circular due to shape constancy.

Brightness/Color Constancy

We perceive objects as being a constant color even as the light reflecting off the object changes. \n For example, we will perceive a brick wall as red even though the daylight fades and the actual color reflected from the wall turns gray.

Perceptual Adaptation

The ability to adjust to changed sensory input. \n In vision, the ability to adjust to an artificially displaced or even inverted visual field

Audition (Hearing)

The hearing process occurs in several steps: \n Sound waves, vibrations in the air, travel through the air, and are then collected by our ears. \n Sound waves have amplitude and frequency. \n Amplitude is the height of the wave and determines the loudness of the sound, which is measured in decibels. \n Frequency, which is measured in megahertz, refers to the length of the waves and determines pitch. \n Vibrations enter the ear and vibrate the eardrum, which connects with three bones in the middle ear: the hammer (or malleus), the anvil (or incus), and the stirrup (or stapes), \n The vibration is transferred to the oval window, a membrane very similar to the eardrum. \n The oval window membrane is attached to the cochlea, where the process of transduction occurs and neural messages are sent to the auditory cortex in the temporal lobe.

Frequency

The number of complete wavelengths that pass a point in a given time (for example, per second) \n In hearing, measured in Hertz (Hz) \n Determine the pitch of the tone heard

Pitch

A tone's experienced highness or lowness; depends on frequency. \n Measured in Hertz (Hz)

Sound Waves

Vibrations in the air. They travel through the air and are collected by our ears. \n Sound waves have amplitude and frequency. \n Amplitude is the height of the wave and determines the loudness of the sound, which is measured in decibels. \n Frequency, which is measured in megahertz, refers to the length of the waves and determines pitch.

Cochlea

The process of transduction (where sound waves are changed into neural impulses) occurs here. \n Shaped like a snail's shell and filled with fluid. As sound waves move the fluid, hair cells move. Neurons are activated by the movement of the hair cells. \n Neural messages are sent to the auditory cortex in the temporal lobe.

Place Theory (Pitch)

Theory that explain how we hear different pitches or tones. \n Place Theory explains that the hair cells in the cochlea respond to different frequencies of sound based on where they are located in the cochlea.

Frequency Theory (Pitch)

Theory that explain how we hear different pitches or tones. \n The rate of nerve impulses traveling up the auditory nerves matches the frequency of the tone, thus enabling us to sense its pitch. Also called temporal theory. \n 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 the cells fire. We sense pitch because the hair cells fire at different rates (frequencies) in the cochlea.

Sound Shadow

An area of reduced sound intensity around the ear farther away from where a sound originates. \n Helps us localized sounds.

Sensorineural Hearing Loss/Nerve Deafness

Occurs when receptor (hair or cilia) cells in the cochlea or auditory nerves have been damaged, usually by loud noise. \n Most common form of hearing loss.

Conduction Hearing Loss/Conduction Deafness

Something goes wrong with the mechanical system of conducting the sound to the cochlea (in the ear canal, eardrum, hammer/anvil/stirrup, or oval window). \n Difficult to treat because there is no method yet found that will encourage the hair cells to regenerate. \n Less common form of hearing loss.

Cochlear Implant

A device for converting sounds into electrical signals and stimulating the auditory nerve through electrodes threaded into the cochlea.

Touch

This sense is activated when our skin is indented, pierced, or experiences a change in temperature. \n Some nerve endings in the skin respond to pressure; others respond to temperature. \n The brain interprets the amount of indentation (or temperature change) as the intensity of the touch, from a light touch to a hard blow. \n We sense placement of the touch by the place on our body where the nerve endings fire. \n Nerve endings are more concentrated in different parts of our body. If we want to feel something, we usually use our fingertip, an area of high nerve concentration, rather than the back of our elbow, area of low nerve concentration. \n - Pain is a useful response because it warns us of potential dangers.

Gate Control Theory

Explains how we experience pain. \n The theory that the spinal cord contains a neurological "gate" that blocks pain signals or allows them to pass on to the brain. The "gate" is opened by the activity of pain signals traveling up small nerve fibers and is closed by activity in larger fibers or by information coming from the brain. \n Some pain messages have a higher priority than others. When a high-priority message is sent, the gate swings open for it and shut for low-priority messages, which will not be felt. \n Of course, this gate is not a physical gate swinging in the nerve; it is just a convenient way to understand how pain messages are sent. For example, when you scratch an itch, the gate swings open for your high-intensity scratching and shuts for the low-intensity itching; this stops the itching for a short period of time. \n 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 (or Gestation)

Nerves involved in the chemical senses (taste and smell) respond to chemicals rather than to energy. \n Taste buds on the tongue absorb chemicals from the food we eat. \n Taste buds are located on papillae, the bumps you can see on your tongue. Taste buds are located all over the tongue and on some parts of the inside of the cheeks and roof of the mouth. \n Humans taste five different types of tastes: sweet, salty, sour, bitter, and umami. \n People differ in their ability to taste food. The more densely packed the taste buds, the more chemicals are absorbed, and the more intensely the food is tasted. \n The flavor of food is actually a combination of taste and smell.

Smell (or Olfactor)

Molecules of substances rise into the air and are drawn into our nose. \n The molecules settle in a mucous membrane at the top of each nostril and are absorbed by receptor cells located there. \n As many as 100 different types of smell receptors may exist. These receptor cells are linked to the olfactory bulb, which gathers the messages from the olfactory receptor cells and sends this information to the brain. \n Nerve fibers from the olfactory bulb connect to the brain at the amygdala and then to the hippocampus, which make up the limbic system, which is responsible for emotional impulses and memory. \n This direct connection to the limbic system may explain why smell is such a power trigger for memories.

Vestibular Sense

This sense tells us about how our body is oriented in space. Three semicircular canals in the inner ear give the brain feedback about body orientation. \n When the position of your head changes, the fluid moves in the canals, causing sensors in the canals to move. \n The movement of these hair cells activate neurons, and their impulses go to the brain. \n For example, this sense helps us figure out which way is up or down when doing a flip.

Kinesthetic Sense (Kinesthesia)

Gives us feedback about the position and orientation of specific body parts. \n Receptors in our muscles and joints send information to our brain about our limbs. \n This information, combined with visual feedback, lets us keep track of our body.

Sensory Interaction

the principle that one sense may influence another, as when the smell of food influences its taste.

Embodied Cognition

In psychological science, the influence of bodily sensations, gestures, and other states on cognitive preferences and judgments. \n For example, physical warmth may promote social warmth, while social exclusion can literally feel cold.

Synesthesia

When one kind of sensory stimulus evokes the subjective experience of another. \n Neurons for different types of cognition or sensation may be linked together in the brain. \n For exampled, hearing music may activate color-sensitive cortex regions and trigger a sensation of color. \n People who experience such sensory shift are called synesthetes.