The body receives information through the five main senses. The Five Human Senses HearingVisionTasteSmellTouch

 Sensation  a process by which our sensory receptors and nervous system receive and represent stimulus energy  Perception  a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events Sensation

 Bottom-Up Processing  analysis that begins with the sense receptors and works up to the brain’s integration of sensory information  Top-Down Processing  information processing guided by higher-level mental processes  as when we construct perceptions drawing on our experience and expectations Sensation

 Our sensory and perceptual processes work together to help us sort out complex processes

How Many Wolves?

 Psychophysics  study of the relationship between physical characteristics of stimuli and our psychological experience of them  Light- brightness  Sound- volume  Pressure- weight  Taste- sweetness Sensation - Basic Principles

 Absolute Threshold  minimum stimulation needed to detect a particular stimulus 50% of the time  Difference Threshold  minimum difference between two stimuli required for detection 50% of the time  just noticeable difference (JND) Sensation - Threshold

An absolute threshold is the minimal amount of sensory stimulation needed for a sensation to occur.

 Signal Detection Theory  predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)  assumes that there is no single absolute threshold  detection depends partly on person’s  experience  expectations  motivation  level of fatigue

 Subliminal  When stimuli are below one’s absolute threshold for conscious awareness Low Absolute threshold Medium Intensity of stimulus Percentage of correct detections Subliminal stimuli Subliminal Messages

Subliminals?

 Weber’s Law- to perceive as different, two stimuli must differ by a constant minimum percentage  light intensity- 8%  weight- 2%  tone frequency- 0.3%  Sensory adaptation- diminished sensitivity as a consequence of constant stimulation Sensation

 Transduction  conversion of one form of energy to another  in sensation, transforming of stimulus energies into neural impulses  Wavelength  the distance from the peak of one wave to the peak of the next Vision

 Hue  dimension of color determined by wavelength of light  Intensity  amount of energy in a wave determined by amplitude  brightness  loudness Vision

Short wavelength=high frequency (bluish colors, high-pitched sounds) Long wavelength=low frequency (reddish colors, low-pitched sounds) Great amplitude (bright colors, loud sounds) Small amplitude (dull colors, soft sounds) Vision-Physical

Light: The Visual Stimulus Light can be described as both a particle and a wave Wavelength of a light is the distance of one complete cycle of the wave Visible light has wavelengths from about 400nm to 700nm Wavelength of light is related to its perceived color

The spectrum of electromagnetic energy

Vision Cornea– the outer covering of the eye Pupil- adjustable opening in the center of the eye

Vision § Iris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening § Lens- transparent structure behind pupil that changes shape to focus images on the retina (like camera lens)

Vision

§ Accommodation- the process by which the eye’s lens changes shape to help focus near or far objects on the retina § Retina- the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual information

Vision § Acuity- the sharpness of vision § Nearsightedness- condition in which nearby objects are seen more clearly than distant objects because distant objects in front of retina § Farsightedness- condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind retina

Vision § Farsighted NearsightedNormal Vision Vision Vision

Retina’s Reaction to Light- Receptors § Rods § peripheral retina § detect black, white and gray § twilight or low light § Cones § near center of retina § fine detail and color vision § daylight or well-lit conditions

Color Vision Our visual system interprets differences in the wavelength of light as color Rods are color blind, but with the cones we can see different colors This difference occurs because we have only one type of rod but three types of cones

Retina’s Reaction to Light § Optic nerve- nerve that carries neural impulses from the eye to the brain § Blind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there § Fovea- central point in the retina, around which the eye’s cones cluster

Blindspot

Vision- Receptors Receptors in the Human Eye ConesRods Number Location in retina Sensitivity in dim light Color sensitive?Yes Low Center 6 million No High Periphery 120 million

Rods Cones

Processing Visual Information Ganglion cells— neurons that connect to the bipolar cells, their axons form the optic nerve Bipolar cells— neurons that connect rods and cones to the ganglion cells Optic chiasm— point in the brain where the optic nerves from each eye meet and partly crossover to opposite sides of the brain

Visual Pathway Axons of the ganglion cells come together to form the optic nerve Half of optic nerve fibers cross into opposite hemisphere and synapse onto LGN (lateral geniculate nucleus) LGN neurons synapse onto primary visual cortex

Pathways from the Eyes to the Visual Cortex

 Feature Detectors  nerve cells in the brain that respond to specific features  shape  angle  movement Stimulus Cell’s responses Visual Information Processing

How The Brain Perceives The Necker Cube

Illusory Contours

 Parallel Processing  simultaneous processing of several aspects of a problem simultaneously Visual Information

Color Mixing Two basic types of color mixing  subtractive color mixture example: combining different color paints  additive color mixture example: combining different color lights

Additive Color Mixture By combining lights of different wavelengths we can create the perception of new colors Examples:  red + green = yellow  red + blue = purple  green + blue = cyan

Trichromatic Theory of Color Vision Researchers found that by mixing only three primary lights (usually red, green and blue), they could create the perceptual experience of all possible colors This led Young and Helmholtz to propose that we have three different types of photoreceptors, each most sensitive to a different range of wavelengths

Visual Information Processing § Trichromatic (three color) Theory § Young and Helmholtz § three different retinal color receptors § red § green § blue

Color Vision Some people cannot tell the difference between certain colors. The most common form is the inability to see the colors of red or green.

 People who suffer red-green blindness have trouble perceiving the number within the design Color-Deficient Vision

Opponent Process Theory of Color Vision Some aspects of our color perception are difficult to explain by the trichromatic theory alone Example: afterimages  if we view colored stimuli for an extended period of time, we will see an afterimage in a complementary color

Color Blindness

Visual Information Processing Opponent-Process Theory- opposing retinal processes enable color vision “ON”“OFF” red green green red blue yellow yellow blue black white white black

Opponent Process- After Image

Complimentary- After Image

Opponent-Process Theory To account for phenomena like complementary afterimages, Herring proposed that we have two types of color opponent cells  red-green opponent cells  blue-yellow opponent cells Our current view of color vision is that it is based on both the trichromatic and opponent process theory

 Color Constancy  Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object Visual Information Processing

Overview of Visual System The eye is like a camera, but instead of using film to catch the light we have rods and cones Cones allow us to see fine spatial detail and color, but cannot function well in dim light Rods enable us to see in dim light, but at the loss of color and fine spatial detail Our color vision is based on the presence of 3 types of cones, each maximally sensitive to a different range of wavelengths

Audition § Audition § the sense of hearing § Frequency § the number of complete wavelengths that pass a point in a given time § Pitch § a tone’s highness or lowness § depends on frequency

The Intensity of Some Common Sounds

Audition- The Ear § Outer Ear § ear lob and auditory canal § Middle Ear § chamber between eardrum and cochlea containing three tiny bones (hammer, anvil, stirrup) that concentrate the vibrations of the eardrum on the cochlea’s oval window

Audition- The Ear § Inner Ear § innermost part of the ear, continuing the cochlea, semicircular canals, and vestibular sacs § Cochlea § coiled, bony, fluid-filled tube in the inner ear through which

Transduction of Sounds  The structures of the ear transform changes in air pressure (sound waves) into vibrations of the Basilar Membrane  As the Basilar Membrane vibrates it causes the hairs in the Hair Cells to bend  The bending of the hairs leads to a change in the electrical potential within the cell

Audition § Place Theory § the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated § Frequency Theory § the theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch

How We Locate Sounds

Audition § Conduction Hearing Loss § hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea § Nerve Hearing Loss § hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve

Audition § Older people tend to hear low frequencies well but suffer hearing loss for high frequencies 1 time 10 times 100 times 1000 times Frequency of tone in waves per second LowPitchHigh Amplitude required for perception relative to year-old group

Chemical and Body Senses Olfaction (smell) Gustation (taste) Touch and temperature Pain Kinesthetic (location of body) Vestibular (balance)

Touch § Skin Sensations § pressure § only skin sensation with identifiable receptors § warmth § cold § pain

Pain § Gate-Control Theory (Melzack & Wall) § theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain § “gate” opened by the activity of pain signals traveling up small nerve fibers § “gate” closed by activity in larger fibers or by information coming from the brain

Taste § Taste Sensations  sweet  sour  salty  bitter § Sensory Interaction  the principle that one sense may influence another  as when the smell of food influences its taste

Taste Sweet Sour Salty Bitter

Smell Receptor cells in olfactory membrane Nasal passage Olfactory bulb Olfactory nerve

Age, Sex and Sense of Smell Women Men Age Group Number of correct answers Women and young adults have best sense of smell

Body Position and Movement  Kinesthesis  the system for sensing the position and movement of individual body parts  Vestibular Sense  the sense of body movement and position  including the sense of balance