Unit 3: Sensation and Perception

the process by which we receive physical energy from the environment and encode it into neural signals.

the process of organizing and interpreting sensory information.

analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information.

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

the focusing of conscious awareness on a particular stimulus.  Also known as the cocktail party effect.

failing to see visible objects when our attention is directed elsewhere. 

The video in class:

When attending to one task (counting basketball passes by one of the three-person teams) about half the viewers displayed inattentional blindness by failing to notice a clearly visible gorilla passing through.  This also happened in an experiment with a woman walking across the screen with an umbrella.

failing to notice changes in the environment. 

Ex. The bearded man not noticing that the man giving directions was replaced by someone else after the board passed by.

the study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.

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

predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise).  This theory assumes there is no single absolute threshold and that detection depends partly on a person’s experience, expectations, motivation, and alertness.

below one’s absolute threshold for conscious awareness.

the activation, often unconsciously, of certain associations, thus predisposing one’s perception, memory, or response.

the minimum difference between two stimuli required for detection 50% of the time.  We experience this difference threshold as a just noticeable difference (jnd).

the principle that, to be perceived as different, two stimuli must differ by a constant percentage (rather than a constant amount). 

diminished sensitivity as a consequence of constant stimulation. Ex. hot tub no longer feeling hot because you have gotten “used” to it.

the sense of sight.

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

the ring of muscle tissue that forms the colored portion of the eye and that controls the size of the pupil opening.

the transparent structure behind the pupil that changes shape to help focus images on the retina.

process of the lens changing shape to help focus images on the retina.

the light-sensitive inner surface of the eye that contains the receptor rods and cones plus layers of neurons that begin the processing of transduction for vision.

retinal receptors that detect black, white, and shades of gray that are necessary for peripheral and twilight vision when cones don’t respond.  The human eye has around 120 million rods.

retinal receptors that are concentrated near the center of the retina that detect colors and details and that function in the daylight or in well-lit conditions.  The human eye has around 6 million cones.

the central focal point in the retina, around which the eye’s cones cluster.

the nerve that carries neural impulses from the eye to the brain.

the point at which the optic nerve leaves the eye, creating a “blind’ spot because there are no receptor cells located there.

specialized neurons that connect the rods and cones w/the ganglion cells.

specialized neurons that connect to the bipolar cells.  The bundled axons of the ganglion cells form the optic nerve.

nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement.

the brain’s natural mode of information processing many things at once, such as color, motion, form, and depth.

the theory that the retina contains three different color receptors (red, green, and blue) which, when stimulated in combination can produce the perception of any color.

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision.  This explains the afterimage effect (staring at a yellow, green, and black flag and when looking away, you see red, white, and blue).

sharpness of vision.

a condition in which nearby objects are seen clearly but distant objects are blurred because light rays reflecting from them converge in front of the retina.

a condition in which distant objects are seen clearly but nearby objects are blurred because light rays reflecting from them strike the retina before converging.

the sense of hearing.

the number of complete wavelengths that pass a point in a given time.  Frequency determines the pitch.

a tone’s highness or lowness.  The shorter the waves, the higher the pitch; the longer the waves, the lower the pitch.

the strength of a wave.  This is measured from peak to trough.  The taller the wave, the louder the sound; the shorter the wave, the softer the sound.

the sound of a tone.  It allows you to distinguish between two similar sounds.  Ex. Hearing the difference between a flute and a piccolo. 

the part of the ear that traps sound waves and channels them through the auditory canal to the eardrum.

the fleshy outside part of the ear.

the canal in the outer part of the ear down which sound waves travel.  At the end of the auditory canal is the eardrum.

the tight membrane that vibrates when sound waves hit it.

the part of the ear that transmits the eardrum’s vibrations through a piston made of three tiny bones (hammer, anvil, and stirrup) to the cochlea.

the innermost part of the ear that contains the cochlea, semicircular canals, and vestibular sacs (important for balance).  This is where transduction happens for sound.

A membrane inside the cochlea which vibrates in response to sound and whose vibrations lead to activity in the auditory pathways.

the nerve that sends neural messages (via the thalamus) to the temporal lobe’s auditory cortex.

links pitch we hear with the place where the cochlea’s membrane is stimulated. This theory can explain how we high-pitched sounds, but now how we hear low-pitch sounds because the neural signals generated by low-pitched sounds are not so neatly localized on the basilar membrane.

states that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch. 

neural cells alternate firing.  By firing in rapid succession, they can achieve a combined frequency.

hearing loss caused by damage to the mechanical system, such as the three bones, that conducts sound waves to the cochlea.  A hearing aid may help amplify sounds for someone who has conduction hearing loss.

 hearing loss caused by damage of the cochlea’s receptor cells or to the auditory nerves.  It is also called nerve deafness.  This can be caused by disease, but are more often the culprits of biological changes linked heredity, aging, and prolonged exposure to ear-splitting noise or music.

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

the outside layer of skin.

the inside layer of skin.

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.

feeling sensations or movement in limbs that have been removed.

a phantom auditory sensation in which people hear ringing in the ears.

sensory receptors that detect hurtful temperatures, pressure, or chemicals.

 the body’s natural painkillers.

the sense of taste.  There are 5 basic tastes: sweet, salty, sour, bitter, and umami (taste of meat).

structures on the tongue in which the taste buds are located.

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

a perceptual phenomenon which demonstrates an interaction between hearing and vision in speech perception. This effect may be experienced when a video of one phoneme's production is dubbed with a sound-recording of a different phoneme being spoken. Often, the perceived phoneme is a third, intermediate phoneme. For example, a visual /ga/ combined with an audio /ba/ is often heard as /da/.

 the sense of smell.

a chemical compound that has smell.

the place in the nasal cavity where transduction occurs for smell. *Remember that smell does not go to the thalamus.  It goes directly to the amygdala and then the hippocampus. → Bad smells make people angry and smells make strong memories.

the sense of body movements and position, including the sense of balance.

the system for sensing the position and movement of individual body parts.

sensors that are located in the skin, joints, muscles, and tendons for kinesthesis.

the process of organization and interpreting sensory information, enabling us to recognize meaningful objects and events.

an organized whole.  Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes.

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

the perceptual tendency to organize stimuli into coherent groups.

 We group nearby figures together.

We group similar figures together.

We perceive smooth, continuous patterns rather than discontinuous ones.

Because they are uniform and linked, we perceive each set of two dots and the line between them as a single unit. 

We fill in gaps to create a complete, whole object.

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

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

depth cues, such as retinal disparity, that depends on the use of two eyes.  *Remember bi means two so you need 2 eyes for disparity.

depth cues that depend on the use of one eye.  *Remember mono means one.

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.

 we perceive objects higher in our field of vision as farther away.

if we assume two objects are similar in size, most people perceive the one that casts the smaller retinal image as farther away.

if one object partially blocks our view of another, we perceive it as closer.

parallel lines, such as railroad tracks, appear to converge with distance.  The mover they converge, the greater their perceived distance.

As we move, objects that are actually stable may appear to move.

nearby objects reflect more light to our eyes. Thus, given two identical objects, the dimmer one seems farther away.  Shading, too, produces a sense of depth consistent with our assumption that light comes from above. 

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

perceiving objects as unchanging (having consistent shapes, size, lightness, and color) even as illumination and retinal images change.

perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object.