4.1: Sensation

Transduction: The Sense Organs’ Primary Job

• Transducers: Devices that convert one kind of energy into another.

• Sensation: Conversion of energy from the environment into a pattern of response by the nervous system; also a sensory impression.

  Psychophysics: Meaning Sensory Impressions

• Psychophysics: Study of how the mind interprets the physical properties of stimuli.

• Absolute threshold: Minimum amount of physical energy that can be detected 50 percent of the time.

• Difference threshold: Minimum difference in physical energy between two stimuli that can be detected 50 percent of the time.

  Sensory Adaptation

• Sensory adaption: A decrease over time in sensory response to an unchanging stimulus.

  Feature Detection

• Perceptual features: Basic attributes of a stimulus, such as lines, shapes, edges, or colors.

• Feature detector: Cells in the cortex that respond to a specific attribute of an object.

  4.2: Vision

  Characteristics of Light: What the Eye Sees

• Hue: Color of light, determined by its wavelength.

• Saturation: Purity of hues

• Brightness: Cause color to appear brighter or intense

  The Process of Accommodation in the Eye: Focus!

• Cornea: Curved, transparent, protective layer through which light enters the eye.

• Lens: Clear structure behind the pupil that bends light toward the retina.

• Accommodation: Changes in the shape of lens of the eye to enable the seeing of  close and far objects.

• Hyperopia: Having difficulty focusing on nearby objects (farsightedness).

• Myopia: Having difficulty on distant objects (nearsightedness).

• Astigmatism: Defects in the cornea, lens, or eye that cause some areas of vision to be out of focus.

• Presbyopia: Farsightedness caused by aging.

  The Process of Transduction in the Eye

• Retina: Surface at the back of the eye onto which the lens focuses light rays.

• Cones: Photoreceptors that are sensitive to color.

• Rods: Photoreceptors for dim light that produce only black and white sensations.

• Visual acuity: The sharpness of visual perception.

• Blind spot: Area in the retina where the optic nerve exits that contains no photoreceptor cells.

• Optic nerve: Structure that conveys visual information away from the retina to the brain.

  Cones

• Fovea: Tiny spot in the center of the retina, containing only cones, where visual acuity is greatest.

  Vision in Everyday Life: Color Blindness

• Color blindness: A total inability to perceive color.

• Color weakness: An inability to distinguish some colors.

• Introduction to Psychology: Gateway to Mind and Behavior (16th Edition)

  Rods

• Peripheral (side) vision: Vision at the edges of the visual field.

• Dark adaption: Increased light sensitivity of the eye under low-light conditions.

• Pupil: The back opening inside the iris that allows light to enter the eye.

• Iris: Colored structure on the surface of the eye surrounding the pupil.

  Theories of Color Vision

• Trichromatic theory of color vision: A theory of color vision based on three cone types: red, green, and blue.

• Opponent-process theory of color vision: Proposition that color vision is based on coding things as red or green, yellow or blue, or black or white.

  4.3: Hearing

  Characteristics of Sound: What the Ear Hears

• Pitch: How high or low a tone sounds; related to the frequency of a sound wave.

• Loudness: The volume of a sound; related to the amplitude of a sound wave.

• Eardrum: Membrane that vibrates in response to sound waves and transmits them inward.

• Cochlea: Snail-shaped organ in the inner ear that contains sensory receptors for hearing.

• Basilar membrane: Structure in the cochlea containing hair cells that convert sound waves into action potentials.

• Hair cells: Receptor cells within the cochlea that transduce vibrations into nerve impulses.

  Hearing Loss

• Conductive hearing loss: Poor transfer of sounds from the eardrum to the inner ear.

• Sensorineural hearing loss: Loss of hearing caused by damage to the inner-ear hair cells or auditory nerve.

• Noise-induced hearing loss: Damage caused by exposing the hair cells to excessively loud sounds.

• Frequency theory of hearing: Proposition that pitch is decoded from the rate at which hair cells of the basilar membrane are firing.

• Place theory of hearing: Proposition that higher and lower tones excite specific areas of the cochlea.

  4.4: Chemical and Somesthetic Sense

• Olfaction: Sense of smell.

• Gustation: Sense of taste.

• Somesthetic Sense: ability to “feel

• Skin senses: The senses of touch, pressure, pain, heat, and col.

• Kinesthetic senses: The senses of body movement and positioning.

• Vestibular senses: Perception of balance, gravity, and acceleration.

  Theory of Odor Detection

• Anosmia: Smell blindness

• Lock-and-key theory of olfaction: A theory holding that odors are related to the shapes of chemical molecules.

  Taste

• 5 Basic Taste Sensations

  • sweet

  • salty

  • sour

  • bitter

  • umami (brothyt)

  The Process of Transduction on the Tongue

• Taste buds: Receptors for taste.

  Touch

• Touch: First of somesthetic senses

• Anaphia: loss of feeling

  Process of Transduction on the Skin

• Light touch, pressure, pain, cold, warm

• Sensitivity = more receptors

• Warning system: Pain based on large nerve fibers; warns that bodily damage may be occurring.

• Reminding system: Pain based on small nerve fibers; reminds the brain that the body has been injured.

  The Pain Gate

• Gate control theory: A theory proposing that pain messages pass through neural “gates” in the spinal cord.

  Sensation in Everyday Life: Motion Sickness

• Multimodal integration: The process by which the brain combines information coming from multiple senses.

  4.5: Attention

• Selective attention: Giving priority to a particular incoming sensory message.

  Four Factors Influencing Selective Attention

  Intensity

• Intense stimuli command attention

• We naturally focus on brighter, louder, larger, and sharper stimuli

  Contrast

• Attention is also frequently related to contrast - change in stimulation

• Contrast between bold, *italics, *CAPITALS, and lowercase can draw your attention

  Personal Importance

• Humans are most likely to give their attention to things we find important

  Goals

• Attention can be diverted to things that will help us meet our goals or expectations

• Inattentional blindness: A failure to notice a stimulus because attention is focused elsewhere.

• Change blindness: A failure to notice that the background is changing because attention is focused elsewhere.

  Attention in Everyday Life: Mind-wandering

• Mind-wandering: The process by which attention is withdrawn from the physical environment to focus on internal events.

  4.6: Perception

• Synesthesia: A perceptual phenomenon in which stimulation of one sensory system creates perceptual experiences in another sensory system.

• Perception: Selection, organization, and interpretation of sensory input.

• Illusion: A misleading or misconstructed perception.

• Hallucination: Perception with no basis in reality.

• Perceptual construction: A metal model of external events.

  Bottom-Up and Top-Down Processing

• Bottom-up processing: Organizing perceptions by beginning with low-level features.

• Top-down processing: Perception guided by prior knowledge or expectations.

• Figure-ground organization: Organizing a perception so that part of a stimulus appears to stand out as an object (figure) against a less prominent background (ground).

  Shape, Size, and Brightness Constancy

• Shape constancy: The principle that the perceived shape of an object is unaffected by changes in its retinal image.

• Size constancy: The principle that the perceived size of an object remains constant, despite changes in its retinal image.

• Brightness constancy: The principle that the apparent (or relative) brightness of objects remains the same so long as they are illuminated by the same amount of light.

• Muller-Lyer illusion: Two equal-length lines tipped with inward or outward pointing Vs appear to be of different lengths.

  The Basics of Depth Perception

• Depth perception: The ability to see three-dimensional (3-D) space and to judge distances accurately.

  Depth Perception and the World of Art

• Depth cues: Features of the environment and messages from the body that supply information about distance and space.

• Binocular depth cues: Perceptual features that impart information about distance and three-dimensional (3-D) space that require two eyes.

• Retinal disparity: Difference between the images projected onto each eye.

• Stereoscopic vision: Perception of space and depth as a result of each eye receiving different images.

• Convergence: Degree to which the eyes turn it to focus on a close object.

• Monocular depth cues: Perceptual features that impart information about distance and three-dimensional (3-D) space that require just one eye.

• Pictorial depth cues: Monocular depth cues found in paintings, drawings, and photographs that impart information about space, depth, and distance.

  • Linear Perspective

  • Relative Size

  • Height in the Plane

  • Light and Shadow

  • Texture Gradients

  • Relative Motion

• Virtual reality: Environment in which sensory stimuli (such as sights and sounds) are provided by computer software to realistically simulate “real world” events.

  4.7: Psychology and Your Skill Set: Effective Communication

  Receiving Information: Reading and Listening

• Things we should be aware of when listening to others:

  • Don’t interrupt the speaker

  • Show the speaker that you are listening through verbal cues

  • Keep an open mind while you are listening

  • Ask clarifying questions

  • Focus on what’s being said

Chapter in Review:

4.1 Sensation

Define sensation and transduction, and outline what happens in the sensory organs during transduction

Sensation is the process by which information from the world is gathered by the sensory organs and then sent on to the brain. Transduction is the process by which one form of energy is converted into another. The sense organs (eyes, ears, skin, tongue) transduce various forms of energy found in the environment (e.g., from sound) into electrical energy in the form of action potentials so that the brain can understand the information taken in by the senses.

Distinguish between absolute threshold and difference threshold

Absolute threshold refers to the minimum amount of sensory input that must be present for physical energy (light; sound) to be detected 50 percent of the time. In contrast, difference threshold refers to the minimum difference that must exist between two stimuli for that difference to be detected 50 percent of the time.

Identify four ways by which the senses reduce the amount of information sent to the brain

The senses act as selective data selection systems to prevent the brain from being overwhelmed by sensory input. Four ways by which this happens are: a lack of specific transducers, the restricted range of transducers, sensory adaption, and feature detection.

4.2 Vision

Describe three characteristics of light that are processed by the eye

The eye takes in information about hue (associated with the frequency or wavelength of the light wave), saturation (associated with the width of the band of wavelengths), and brightness (associated with the amplitude of the light wave).

Outline what is meant by accommodation in the eye, and the conditions that result from problems with accommodation

Accommodation refers to the eye’s ability to focus, and is carried out by the lens. Four common visual defects are myopia, hyperopia, presbyopia, and astigmatism.

Describe the process of transduction in the eye, and two problems associated with color vision

The rods and cones are photoreceptors in the retina of the eye. The rods soecualize in peripheral vision, night vision, seeing black and white, and detecting movement. The cones specalize in color vision, acuity, and daylight vision. People may experience color blindness (an inability to perceive color), or color weakness (an inability to see certain colors).

Contrast the trichromatic and opponent-process theories of color vision

Color vision is explained by the trichromatic theory within the retina itself, where three types of cones (red, blue, green) containing different pigments are responsible for generating action potentials. The opponent-process theory explains color vision beyond the retina, once the information about color is sent to the optic nerve.

4.3 Hearing

Describe two characteristics of sound that are processed by the ear

The ear takes in information about pitch (associated with the frequency of the sound wave) and loudness (associated with the amplitude of the sound wave).

Describe the process of transduction in the ear, and two associated forms of hearing loss

Sound waves are the stimulus for hearing. They are amplified and directed by the eardrum, auditory ossicles, and oval window to the cochlea, where they are transduced by the hair cells to generate action potentials. Two basic types of hearing loss are conductive hearing loss (caused when the transfer of vibration from the outer ear to the inner ear weakens) and sensorineural hearing loss (caused when there is damage to the hair cells or auditory nerve). Noise-induced hearing loss is a common form of sensorineural hearing loss caused by exposure to loud noise.

Contrast the frequency and place theory of hearing pitch

Frequency of theory (pitch corresponds to frequency of action potentials) explains how we hear tones up to 4,000 hertz; place theory (higher and lower tones are associated with excitation of different parts of the cochlea) explains for tones about 4,000 hertz.

4.4 Chemical and Somesthetic Senses

Name the two chemical senses and three somesthetic senses

Olfaction (smell) and gustation (taste) are chemical senses that respond to airborne or liquefied molecules. The somesthetic senses include touch, the vestibular senses (responsible for balance), and the kinesthetic senses (responsible for detecting the position of your body parts in space).

Describe the process of transduction in the nose

Receptors on nerve fibers in the nose are sensitive to various chemical molecules and create action potentials when they are stimulated. The lock-and-key theory of olfaction suggests different receptors have differently shaped “holes” that can bind with matching chemical molecules, creating the basis for a unique smell. In addition, the location of the olfactory receptors in the nose helps people identify various scents.

Describe the process of transduction of the tongue

There are five basic tastes: sweet, salt, sour, bitter, and umami. Sweet, bitter, and umami tastes are based on a lock-and-key coding of molecule shapes; when there is a match between receptors and the chemical molecules found in food an action potential is activated. Salty and sour tastes are triggered by a direct flow of ions into taste receptors, activating an action potential.

Define multimodal integration

Multimodal integration refers to the brain’s ability to integrate the incoming sensory impressions from multiple senses.

4.5 Attention

Explain what research on multitasking has indicated with respect to the limits on attention

Multitasking research suggests that attention is limited and that rather than carrying out two tasks simultaneously, we typically switch rapidly between tasks. Task switching is easier when at least one of the tasks is well-practiced.

Identify four factors that influence whether we will pay attention to a stimulus

We are most likely to attend to stimuli that are intense, that are unexpected, that are personally important, and that help us to achieve our goals.

Describe the positive and negative effects of mind-wandering

Mind-wandering research has illuminated the fact that when we turn our attention inward from the environment, we are less able to respond to external conditions which can have negative consequences (e.g., traffic accidents; failure to learn from lectures). However, mind-wandering may promote creativity, relief from boredom, and the ability to plan for the future.

4.6 Perception

Describe the relationship between sensation and perception

Sensation is the process by which sensory organs take in information from the environment, while perception is the process by which the brain interprets that information.

Contrast bottom-up and top-down processing

Perceptions are based on simultaneous bottom-up and top-down processing. Complete perceptions can be assembled from small sensory features in “bottom-up” processing. In contrast, preexisting knowledge is applied to sensory information in “top-down” processing to help organize features into a meaningful whole. Top-down processes are at work when we work to separate figure and ground, as well as in the interpretation of reversible and ambiguous figures.

Explain how both sensory transduction and experience contribute to similarities and differences in perception

In many situations, people exposed to the same sensory input will have a similar perceptual experience. Such similarities often arise because sensory transduction typically proceeds the same way across individuals. However, perceptual similarities sometimes result from the fact that we have shared experiences that train the perceptual system in ways that are common across people, resulting in perceptual constancies. Perceptual constancies are “rules of thumb” developed by the brain as a product of years of experience interpreting the environment. They help the brain to quickly process incoming sensory information in ways that are usually accurate. Three examples are size, shape, and brightness constancy.

In some cases, though, people exposed to the same sensory input will have different perceptual experiences. These differences may result from transduction; specifically, differences in transduction can be the product of flaws in the genetic code, environmental trauma, and age-related decline. In all cases, transduction may not work in a typical way (or at all), leading to differences in perception. Experience may also play a role in perceptual differences, particularly when characteristics of the stimuli are ambiguous. In the case of #thedress, for example, the lighting was ambiguous, leading people to use their own unique “defaults” about lighting conditions to interpret the dress’s color. Cultural differences may also have a role to play in our differing perceptual experiences.

Describe the effects of culture on the perception of the Muller-Lyer illusion

The Muller-Lyer illusion is the effect of seeing two straight lines—one with conventional arrowheads at its ends, and the other with V shapes at its ends—as being different lengths, even though they are actually the same. The effect is believed to stem from Western cultures’ experience with the edges and the corners of rooms and buildings. Indeed, in cultures that have little experience with straight lines (like the San of the Kalahari desert), individuals do not experience the illusion to the same extent.

Differentiate between monocular and binocular depth cues, giving examples of each

Depth perception depends on binocular cues (those that require two eyes) of retinal disparity and convergence. Depth perception also depends on the monocular cues (those requiring one eye) that include accommodation and “pictorial” depth cues (linear perspective, light and shadow, overlap, texture gradients, and motion parallax).

Explain how depth cues are used in the world of art and by clinical psychologists using virtual reality to treat clients.

Monocular pictoral depth cues are used by artists to create a sense of three dimensions on flat surfaces such as painting canvases. These same skills with depth cues are now being employed in the creation of realistic virtual reality worlds. Clinicians are now using virtual reality to assist clients with a range of problems, but particularly substance abuse disorders and anxiety disorders. VR technology allows clinicians to simulate real-life conditions for these clients, changing those conditions gradually as therapy progresses.

4.7 Psychology and Your Skill Set: Effective Communication

Distinguish between verbal and nonverbal communication

Two types of communication are nonverbal and verbal. Nonverbal communication refers to the perceptions of other’s actions, such as people’s tone of voice, body language, and eye contact. Verbal communication refers to words.

Outline two verbal communication methods and two verbal communication points of view

There are two verbal communication methods we use to transmit ideas (oral and written) and two verbal communication points of view (providing information or receiving information). The four verbal communication skills that can be developed depending on your method and point of view are: speaking, listening, writing, and reading.

Create a plan to improve your own communication with others

Be mindful of the speaker and being self-aware of your own cues can improve good listening skills. Wringing and speaking skills can be improved by using words that are clear and concrete. When communicating with others, keep in mind that communication styles guided by the extent to which people want to demonstrate power versus foster positive relationships, and the tendency to use jokes, questions, and apologies.