Unit 3: Sensation and Perception

Question 1

What is top-down processing?

Answer 1

Top-down processing is information processing guided by our higher-level mental processes, as when we construct our perceptions drawing on our experience and expectations. It enables us to consider the titles, notice expressions on faces, and find meaning from observations.

Question 2

What is bottom-up processing?

Answer 2

Bottom up processing is when analysis of a stimulus begins with the sense receptors and works up to the level of the brain and mind. It enables us to detect the lines, angles, and colors that form different things.

Question 3

Explain the process of sensation.

Answer 3

Reception > Transduction > Transmission

Question 4

What is reception?

Answer 4

Reception is the stimulation of sensory receptor cells by energy (sound, light, heat, etc).

Question 5

What is transduction?

Answer 5

Transduction transforms a cell’s stimulation into neural impulses.

In vision, we convert light energy into these neural impulses that the brain can understand in a process called phototransduction.

Acoustical transduction: Conversion of sound waves into neural impulses in the hair cells of the inner ear.

Question 6

What is transmission?

Answer 6

Transmission delivers neural information to the brain to be processed.

Question 7

What is psychophysics?

Answer 7

Psychophysics studies the relationship between physical characteristics of stimuli and our psychological experience with them.

Physical World vs Psychological World Experiences:

• Light vs. Brightness
• Sound vs. Volume/Intensity
• Pressure vs. Weight
• Sugar vs. Sweet

Question 8

What is an absolute threshold?

Answer 8

Absolute Threshold: Minimum stimulation needed to detect a particular stimulus (i.e. light, sound, pressure, taste, or odor) 50% of the time.

When you go to have your ears checked, a hearing specialist will expose each of your ears to varying sound levels. For each tone, the test would define where half the time you correctly detect the sound and half the time you do not. For each of your senses, that 50/50 recognition point defines your absolute threshold.

The absolute threshold for hearing is arbitrarily defined as zero decibels (dB). Every 10 decibels corresponds to a tenfold increase in sound. Thus, normal conversation (60 decibels) is 10,000 times louder than a 20 decibel whisper. Prolonged exposure to sounds above 85 decibels can produce hearing loss.

Question 9

What is signal detection theory?

Answer 9

Signal detection theory refers to whether or not we detect a stimulus, especially amidst background noise. This depends not just on intensity of the stimulus but on psychological factors such as the person’s experience, expectations, motivations, and alertness.

Question 10

What is a subliminal threshold?

Answer 10

A subliminal threshold is when stimuli are detectable less than 50% of the time, they are subliminal (or below our conscious level of awareness). Although we cannot learn complex knowledge from subliminal stimuli, we can be primed, and this will affect our subsequent choices. We may look longer at the side of the paper which had just showed a nude image for an instant.

Question 11

What is priming?

Answer 11

Priming is the activation (often unconsciously) of certain associations, which predisposes one’s perceptions, memories, or responses. For instance, a word or image, such as EAT POPCORN or DRINK COKE images at the movies, can briefly prime a later response (i.e. hunger/thirst). However, while subliminally presented stimuli can subtly influence us, experiments have proven that advertisers are NOT able to exploit us with subliminal messages. So although a thirst-quenching Coke or Pepsi ad before a movie might briefly prime us to desire a Coke or Pepsi beverage, it doesn’t mean we will get up and buy one.

Question 12

What is a difference threshold (JND)?

Answer 12

The difference threshold is the minimum difference that a person can detect between any two stimuli 50% of the time. The difference threshold is also called the Just Noticeable Difference (JND) and is illustrated with Weber’s Law. Weber’s Law states that two stimuli must differ by a constant minimum percentage (rather than a constant amount), to be perceived as different.

Question 13

What is sensory adaption?

Answer 13

Sensory adaptation is our diminished sensitivity as a consequence of constant stimulation. Example: Put a band aid or rubber band on your arm, and after awhile you don’t sense it.

Question 14

What is a perceptual set?

Answer 14

A perceptual set is what we expect to see, which influences what we do see. Perceptual set is an example of top-down processing. It’s a mental predisposition to perceive one thing and not another.

Question 15

Explain the effect on emotion, physical state, and motivation on perception.

Answer 15

Experiments show that:

• destinations seem farther when you’re tired.
• a target looks farther when your crossbow is heavier.
• a hill looks steeper with a heavy backpack, or after sad music, or when walking alone.
• something you desire looks closer.

Question 16

What is the visible spectrum?

Answer 16

The energies we experience as visible light are actually a thin slice from the broad spectrum of electromagnetic energy. Our eyes respond to some of these waves. Our brain turns these energy wave sensations into colors. Our sensory experience of light is largely determined by wavelength and intensity.

Longest to shortest wavelength > ROYGBIV

Question 17

What is light energy?

Answer 17

Some organisms are sensitive to differing portions of the electromagnetic spectrum. Bees, for example, cannot see red or yellow but can see ultraviolet light.

Question 18

What makes up the eye?

Answer 18

Cornea, Iris, Pupil, Lens, Retina, Fovea, Blind Spot, Optic Nerve

Question 19

How does the eye work?

Answer 19

Light passes through the cornea and the pupil, and gets focused and inverted by the lens. The light then lands on the retina, where it begins the process of transduction into neural impulses to be sent out through the optic nerve. The lens is not rigid; it can perform accommodation by changing shape to focus on near or far objects.

Question 20

What is the cornea?

Answer 20

Cornea: Transparent disc where light enters the eye. Bends light to provide focus.

Question 21

What is the pupil?

Answer 21

Pupil: Small adjustable opening whose size is regulated by the iris. Pupil dilates in the dark to let in light.

Question 22

What is the iris?

Answer 22

Iris: Muscle that expands/dilates and contracts/constricts to change the size of the opening (pupil) in response to light intensity and inner emotions. Iris dilates when we are interested in someone.

Question 23

What is the lens?

Answer 23

Lens: Behind the pupil. Focuses the light rays on the retina by changing its curvature.

Question 24

What is the retina?

Answer 24

Retina: Multi-layered light sensitive surface containing sensory receptors (rods, cones, and layers of neurons) that process visual information and send it to the brain. The retina is the light-sensitive inner surface of the eye, containing 130 million receptor rods and cones. The retina also contains layers of other neurons (bipolar, ganglion cells) that process visual information.

Question 25

What are rods and cones?

Answer 25

Rods and cones are photoreceptors that transduce light energy into neural signals. These signals activate bipolar cells, which in turn activate ganglion cells, whose axons converge to form the optic nerve, which carries info from the eyes to the brain. When light reaches the back of the retina, it triggers chemical changes in the rods and cones. The rods and cones in turn send messages to ganglion and bipolar cells and on to the optic nerve. Rods help us see the black and white actions in our peripheral view and in the dark. Rods are about 20 times more common than cones, which help us see sharp colorful details in bright light.

Question 26

What are bipolar and ganglion cells?

Answer 26

Bipolar cells receive chemical messages (i.e. visual stimulation) from photoreceptors (rods and cones) and transmit them to ganglion cells, the axons of which converge to form the optic nerve.

Question 27

What is the optic nerve?

Answer 27

Optic nerve: Carries neural impulses from the eye to the visual cortex in the brain’s occipital lobe.

Question 28

What is the blind spot?

Answer 28

Blind Spot: Point where the optic nerve leaves the eye. Because there are no receptor cells located there, a blind spot is created.

Question 29

What is the fovea?

Answer 29

Fovea: Central point in the retina around which the eye’s cones cluster.

Question 30

How is visual information processed?

Answer 30

Optic nerves connect to the thalamus in the middle of the brain, and the thalamus connects to the visual cortex in the occipital lobe.

Question 31

What is feature detection?

Answer 31

Feature Detectors: Nerve cells in the visual cortex that respond only to specific elementary features of a visual stimulus, such as bars, edges, angles, and gradients of light.

Question 32

What is parallel processing?

Answer 32

Parallel processing refers to building perceptions out of sensory details processed in different areas of the brain.

Question 33

What is the Young-Helholtz Trichoromantic Theory?

Answer 33

Young-Helmholtz’s Trichromatic (3 Color) Theory: theory that the retina contains three types of color receptors, each especially sensitive to red, blue or green colors.

Question 34

What is Opponent Process Theory?

Answer 34

Opponent Process Theory: theory that after the leaving the retina’s receptor cells (rods and cones), visual information is analyzed in terms of opponent colors: blue - yellow, green - red, and white – black.

Question 35

What is color blindness?

Answer 35

Color blindness is a genetic disorder in which people are blind to green or red colors.

Question 36

What is a gestalt?

Answer 36

Gestalt psychologists showed that when perceiving a cluster of sensations, we tend to organize them as a gestalt, meaning a “whole” or a “form,” such as in Necker’s Cube. Thus gestalt psychologists emphasize that the whole is more than the sum of its parts.

Question 37

What is figure-ground perception?

Answer 37

Our first task in perception is to perceive any object, called the figure, as distinct from its surroundings, called the ground. For example, this figure-ground illustration continually reverses, demonstrating that the same stimulus can trigger more than one perception.

Question 38

When do humans develop depth perception?

Answer 38

6 months old

Question 39

What are binocular cues?

Answer 39

Binocular (using both eyes) cues exist because humans have two eyes in the front of our head. This gives us retinal disparity; the two eyes have slightly different views, and the more different the views are, the closer the object must be. In an extreme example, your nose is so close that each eye sees a completely opposite half-view of it.

Question 40

What are monocular cues? Give an example.

Answer 40

We intuitively know to interpret familiar objects (of known size) as farther away when they appear smaller.
Examples:
- Relative size
- Relative height
- Interposition
- Relative motion
- Relative clarity
- Linear perspective
- Texture gradient
- Light and shadow

Question 41

What is interposition?

Answer 41

When one object appears to block the view of another, objects that occlude (block) other objects tend to be perceived as closer.

Question 42

What is the Phi Phenomenon?

Answer 42

Phi Phenomenon: When two or more adjacent lights flash at a certain speed, they tend to present illusions of motion. Neon construction signs use this principle to create motion perception, such as those of a moving arrow. Example: Strobe lights use this principle of stroboscopic movement.

Question 43

What is perpetual constancy?

Answer 43

Our ability to see objects as appearing the same even under different lighting conditions, at different distances and angles, is called perceptual constancy. Perceptual constancy is a top-down process.

Question 44

What is color constancy?

Answer 44

Perceiving familiar objects as having consistent color even when changing illumination filters the light reflected by the object.

Question 45

What is lightness/brightness constancy?

Answer 45

The lightness constancy enables us to perceive an object as having a constant lightness (brightness) even when the light that falls on it changes.

Question 46

What is perceptual adaptation?

Answer 46

After our sensory information is distorted, such as by a new pair of glasses or by delayed audio on a television, humans may at first be disoriented but can learn to adjust and function.

Question 47

How do we perceive sound?

Answer 47

• The outer ear collects sound and funnels it to the eardrum.
• In the middle ear, the sound waves hit the eardrum and move the hammer, anvil, and stirrup in ways that amplify the vibrations. The stirrup then sends these vibrations to the oval window of the cochlea.
• In the inner ear, waves of fluid move from the oval window over the cochlea’s “hair” receptor cells. These cells send signals through the auditory nerves to the temporal lobe of the brain.
• Neural messages are sent from the thalamus to the brain’s auditory cortex.

Question 48

What is the cochlea?

Answer 48

Cochlea: Coiled, bony, fluid-filled tube in the inner ear that transforms sound vibrations to neural auditory signals.

Question 49

What is conduction hearing loss?

Answer 49

Hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea. For example, if the eardrum is punctured or if the tiny bones of the middle ear lose their ability to vibrate, the ear’s ability to conduct vibration diminishes.

Question 50

What is sensorineural hearing loss?

Answer 50

Hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve, also called nerve deafness. This type of hearing loss can be caused by disease, aging, or prolonged exposure to ear-splitting noise above 85 dBs. In the case of either conduction or sensorineural hearing loss, a digital hearing aid may restore hearing by amplifying enough sound to stimulate vibrations in neighboring hair cells.

Question 51

What are hearing deficits?

Answer 51

Older people tend to hear low frequencies well, but suffer hearing loss when listening for high frequencies. This high-frequency hearing loss occurs because of nerve degeneration near the beginning of the basilar membrane. This supports Place Theory’s assumptions that different pitches activate different places on the basilar membrane.

Question 52

What is deaf culture?

Answer 52

Cochlear implants (bionic ears) are electronic devices wired into various sites on the auditory nerve that transmit auditory impulses to the brain. Some deaf culture advocates object to using these devices on children because they argue that sign language is a complete language. They also argue that sensory compensation, which enhances other senses, can give deaf people advantages over the hearing community.

Question 53

How do you prevent hearing loss?

Answer 53

• Exposure to sounds that are too loud to talk over can cause damage to the inner ear, especially the hair cells.
• Structures of the middle and inner ear can also be damaged by disease.
• Prevention methods include limiting exposure to noises over 85 decibels and treating ear infections.

Question 54

How do you treat hearing loss?

Answer 54

• People with conduction hearing loss may be helped by hearing aids. These aids amplify sounds striking the eardrum, ideally amplifying only softer sounds or higher frequencies.
• People with sensorineural hearing loss can benefit from a cochlear implant. The implant does the work of the hair cells in translating sound waves into electrical signals to be sent to the brain.

Question 55

What is the place theory?

Answer 55

Place theory suggests that we hear different pitches because different sound waves trigger vibrational activity at different places along the cochlea’s basilar membrane. This explains how we sense high-pitched sounds because the brain can determine a sound’s pitch by recognizing the place on the basilar membrane from which it receives neural signals.

Question 56

What is frequency theory?

Answer 56

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. This best explains how we sense low-pitched sounds. Some combination of Place and Frequency Theories explains how we hear sounds in between high and low pitches.

Question 57

What is the gate-control theory?

Answer 57

This theory hypothesizes that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain

Question 58

What external factors influence pain?

Answer 58

Social Influences: We feel more pain if other people are experiencing pain. This occurs either out of empathy/mirroring, or a shared belief that an experience is painful.

Cultural Influences: We may not pay attention as much to pain if we see a high level of pain endurance as the norm for our family, peer group, or culture.

Question 59

How do we taste?

Answer 59

Each bump on the top and sides of your tongue contains 200+ taste buds, which decrease in number as a result of aging, alcohol, and tobacco use. Each taste bud contains a pore that catches food chemicals. The food molecules are sensed by about 50-100 taste receptor cells that project antenna-like hairs into the pore. These taste receptor cells respond mostly to sweet, salty, sour, or bitter tasting molecules. Everything else that we taste is a combination of these sensations. This response within our taste buds sends a chemical signal that alerts the temporal lobe of the brain, which allows us to process the taste sensations of what we are eating.

Question 60

What is synaesthesia?

Answer 60

Synaesthesia is a condition when perception in one sense is triggered by a sensation in a DIFFERENT sense. Some people experience synaesthesia all the time, reporting that, “the number 7 gives me a salty taste” or “rock music seems purple.”

Question 61

How does smell work?

Answer 61

Like taste, smell is a chemical sense. Sense of smell occurs when odorants enter the nasal cavity and stimulate the 5 million olfactory receptor cells, which recognize individual odor molecules. Once recognized, those neural messages are sent via converging axons to the brain’s olfactory bulb, and then on to higher regions of the brain for processing, including the primary smell cortex of the temporal lobe, and parts of the limbic system. Unlike taste, there are many different forms of smell.

Question 62

What is kinesthesis?

Answer 62

Kinesthesis (“movement feeling”) refers to sensing the movement and position of individual body parts relative to each other.

How it works: sensors in the joints and muscles send signals that coordinate with signals from the skin, eyes, and ears. Without kinesthesis, we would need to watch our limbs constantly to coordinate movement.

Question 63

What is the vestibular sense?

Answer 63

Vestibular sense refers to the ability to sense the position of the head and body relative to gravity, including the sense of balance.

How it works: fluid-filled chambers in the inner ear (vestibular sacs and semicircular canals) have hairlike receptors that send messages about the head’s position to the cerebellum. Vestibular sense serves as the human gyroscope, helping us to balance and stay upright.