Ch 5: Sensation and Pereption

Albert Ames

Constructed a room that was named in his honor, the Ames Room, illistrated vulnerabilities in our depth perception. P200

Auditory Receptors

Nerve carrying sound information from the cochlea to the brain. P212

Binocular Cue

A depth cue that requires the use of both eyes. P200

Monocular Cue

A depth cue that requires the use of only one eye. P200 these cues are found in paintings, artists attempt to provide an illusion of depth in their two-dimensional pieces. Also includes texture gradients and shading. Occlusion is one of the most powerful monocular depth cues/ the blocking of images of distant objects by closer objects. P201

Feature Detector

A hypothetical cell that responds to only one specific visual stimulus. P196 In this hierarchical model the result would be a "grandmother" cell or a single cell that could combine all previous input and processing to tell you that your grandmother is at the door. This type of hyposynthetical neuron, capable of responding to vary specific stimulus and no others, has been referred to as a feature detector. 195-196 It does not fit well with what we know of the visual system. we would need a very large number of feature detectors to respond to all the object and events that we can recognize visually. unable to account for the fact that our expectations influence what we see.

Olfactory Nerve

A nerve carrying olfactory information from the olfactory receptors to the olfactory bulbs. P225 The nerve fibers synapse in one of the 2 olfactory bulbs.

Top-Bottom Processing

A perceptual process in which memory and other cognitive processes are required for interpreting incoming sensory information. P184g when we use the knowledge we have gained from prior experience with stimuli to perceive them. P184 As stimuli become more complicated, like reading a sentence or recognizing a friend in a crowd, we are more likely to engage in top-down processing in addition to bottom-up.

Cone

A photoreceptor in the retina that processes color. P190 Rods and cons are named after there shapes. The human eye contains about 6 million cones. Cones function best under bright light and provide the ability to see both sharp images and color. Are the only true receptors of the visual pathways.

Rod

A photoreceptor specialized to detect dim light. P190 Rods and cons are named after there shapes. The human eye contains about 120 million rods. More sensitive to light than than cones and excel at seeing in the dim light. Become more common as we move from the fovea to the periphery of the retina, so your peripheral vision does a better job of viewing dim light than your central vision does. Rods DO NOT provide information about color, nor do they provide clear, sharp images. Are the only true receptors of the visual pathways.

Taste Buds

A structure found in papillae that contains taste receptor cells. P226 Each contains between 50 and 150 receptor cells which extend tiny hairlike cilia into the saliva that interact with dissolved taste stimuli and transduce the resulting info into neural signals.

Organ of Corti

A structure located on the basilar membrane that contains auditory receptors. P211 contains many rows of hair cells that transduce sound energy into neural signals each human ear has about 15500 of these hair cells. Bending the hair cells stimulates the release of neurotransmitters onto the cells of the auditory nerve. Hair cells stimulate axons forming the auditoy nerve.

Tichromacy Theory

A theory of color vision based on the existence of different types of cones for the detection of short, medium, and long wavelengths. P192 Is consistent with the existence of three types of cones in the retina that respond best to short, medium, or long wavelengths.

Opponent Process Theory

A theory of color vision that suggests we have a red-green color channel and a blue-yellow color channel in which activation of one color in each pair inhibits the other. P193

Fovea

An area of the retina that is specialized for highly detailed vision. P189 Towards the middle of the retina. Specialized for seeing very fine detail. When we stare directly at an object, the image of that object is projected onto the fovea. P190 Is responsible for central vision, as opposed to peripheral vision, which is the ability to see objects off to the side while looking straight ahead.

Pupil

An opening formed by the iris. P188 is actually an opening formed by the muscles of the iris.

Rods and Cones

Are the only true receptors of the visual system. when they absorb light, they trigger responses in four additional layers of neurons within the retina. Axons from the final layer of cells leave the back of the eye to form the optic nerve. P190-191

Pitch Perception

Beings with the basilar membranes of the inner ear. P212

Gustav Fechner (1801-1887)

Developed methods which he called psychophysics, for studying the relationship between stimuli (the physics part) and perception of those stimuli (the psych part or mind part). Fechner's careful methods not only contributed to the establishment of psychology as a true science but are still used in research. P184-185

Retina

Layers of visual processing cells in the back of the eye. P188 A thin but complex network of neurons specialized for the processing of light. Located in the deepest layer of the retina are the specialized receptors the rods and cones, that transduce the light information. Before light reaches these receptors, it must pass through numerous blood vessles and neural layers.

Auditory Nerve

Nerve carrying sound information from the cochlea to the brain. P212 One branch of each "AN" cells makes contact with the hair cells while the other branch proceeds to the medulla of the brainstem. from the medulla, sound info is sent to the midbrain, which manages reflexive responses to sound. The midbrain participates in sound localization or the identification of a source of sound.

Basilar Membrane

Membrane in the cochlea on which the organ of Corti is located. P211 As waves travel through the cochlea, it responds with its own wavelike motion similar to the crack of a whip. This movement causes the hair cells of the organ of corti to move back and forth within the fluid of the cochlear duct.

Optic Tracts

Nerve pathways traveling from the optic chiasm to the thalamus, hypothalamus, and midbrain. P191 Is the optic chiasm until the optic nerve "x's" in the brain About 90% of the axons in the optic tracts will synapse in the thalamus. The remaining fibers connect with the hypothalamus, where their input provides information about light needed to regulate sleep-waking cycles, or with the midbrain, which manages a number of visually guided reflexes, such as changing the size of the pupil in responses to light conditions.

Olfactory Bulb

One of two structures below the frontal lobes of the brain that receive input from the olfactory receptors in the nose. P225 Pathways dont make direct connections with the thalamus before the info reaches the cerebral cortex. instead fibers from the bulbs proceed to the cerebral cortex located in the lower portions of the frontal lobe and to the amygdala. these pathways may account for the sig emotional reactions we experience in response to odor.

Perceiving Loudness

Our perception of loudness doesn't change at the same rate as intensity. When the intensity of a sound is 10x greater than before, we perceive it as being only 2x as loud. P213 Humans can perceive sounds that vary in intensity by a factor of over 10 billion, from the softest sound we can detect up to the sound made by a jet engine. Frequency of sound interacts with our perception of its loudness. Humans are maximally sensitive to sounds that normally fall within the range of human speech ( 80 - 10000 Hz) Sounds falling outside the range of speech must have higher intensity before we hear them well. P214

Pain

Pain info is carried centrally to the brain by 2 types of fibers. Fast, myelinated axons are responsible for that sharp "ouch" sensation that often accompanies an injury. Slower unmyelinated axons responsible for dull, aching sensations are also responsible for "itch" . P221

Frequency Theory

Patterns of neural firing "match" the actual frequency of a sound. P213

Bottom-up Processing

Perception based on building simple input into more complex perceptions. P183 We refer to the brain's use of incoming signals to construct perceptions.

Immanuel Kant

Philosopher who considered olfaction. P223 contrary to what he believes people who have lost there sense of smell due to head injury often experience profound depressions. sharing a meal has a strong effect on bonding for humans and other primates.

Orbitofrontal cortex

Plays an important role in the perception of flavor as the pathways serving olfaction and gustation converge in this part of the brain. P227

Olfactory Receptors

Receptors in the nose interact with airborne chemicals to begin the sensing of odor. P224 Unlike most neurons, the receptors regularly die and are replaced by new receptors are responsible for producing the mucus surrounding the receptors. one branch of each receptor interacts with molecules dissolved in the mucus the other branch carries info back to the central nervous system as part of the Olfactory nerve. P224-225

The Halle Berry Cell

Recordings show that a single cell became active whenever a photo or a drawing of the actress was presented to the patient. The cell even activated when the patient read Berry's name. P197

Papillae

Small bumps on the tongue that contain taste buds. P226 most contain somewhere between 1 and 100 taste buds

Absolute Threshold

The smallest amount of stimulus that can be detected. P185 the smallest possible stimulus that can be detected. EXAMPLE. you can see the equivalent of a candle flame 30 miles away on a moonless night.

Place Theory

Suggests that the frequency of a sound is correlated with the part of the basilar membrane showing a peak response. the base of the basilar membrane, closest to the oval window is narrow and stiff. high frequency near base The further away near the apex, the "BM" is wide and flexible. low frequency near top. works well for sounds above 4000 Hz. Below frequencies of 4000 Hz the response of the "BM" does not allow for precise localization. P213

Localization of Sound

The Pinna helps us localize sounds in the vertical plane, or in the space above or below our head. P214 Our primary method for localizing sound in the horizontal plane (in front, behind, and to the side) is to compare the arrival time of sound at each ear. B/C the head blocks some sound waves, a sound "shadow" is cast on the ear farthest away from the source of sound. As a result, a weaker signal is received by this ear. Our experience has taught us that and the sounds they make usually travel together. P215

Depth Perception

The ability to use the two-dimensional image projected on the retina to perceive three dimensions. P200 Adelbert Ames

Signal Detection

The analysis of sensory and decision making processes in the detection of faint, uncertain stimuli. P186 Is a two step process involving (1) the actual intensity of the stimulus, which will influence observer's belief that the stimulus did occur, and (2) the individual observers criteria for deciding whether the stimulus occurred. P186 Experiments on signal detection provide insight into this type of decision making. In these experiments, trials with a single, faint stimulus and trials with no stimulus at all are presented randomly. The participant states whether a stimulus was present in each trial. P187 Example: is a jury's decision about whether a person is guilty.

Somatosensation

The body senses, including body position, touch, skin, temperature, and pain. P217 stimuli arise from within our body itself or make contact with its surface. as a result, these stimuli do not provide an organism much time to react. Provides essential feedback needed for movement, speech, and safety. We are severely disabled without.

Iris

The brightly colored circular muscle surrounding the pupil of the eye. P188 Means "rainbow" Adjusts the opening of the pupil in response to the amount of light presented in the environment and to signals from the autonomic nervous system. Arousal is associated with dilated pupils, while relaxation is associated with more constricted pupils.

Lens

The clear structure behind the iris and the pupil that bends light toward the retina. P188 Is the main optical instrument of the eye. Muscles attached to the lens can change its shape, allowing us to adjust our focus to see near or distant objects. Behind the lens is the main chamber of the eye, and located on the rear surface of this chamber is the retina.

Cornea

The clear surface at the front of the eye that begins the process of directing light into the retina. P188 Begins the process of bending light to form an image on the back of the eye. Travels to the pupil next

Retinal Disparity

The difference between the images projected onto each eye. P202 One of our most effective depth cues Because this cue requires the use of both eyes, we refer to retinal disparity as a binocular cue. P202 Has been used to identify camouflaged military equipment and counterfeit currency. P203 Magic eyed pictures Infants as young as 4 months can see depth in stereograms as can monkeys, cats, and falcons. P204

Difference threshold

The smallest detectable difference between two stimuli. P185 The amount of difference that can be detected depends on the size of the stimuli being compared. as stimuli gets larger, differences must also become larger to detected by the observer.

Gestalt Psychology

The main thesis of the gestalt, maintains "it is more correct to say that the whole is something else than the sum of its parts. We are born with a number of built-in tendencies to organize incoming sensory information in certain ways. This natural ability to organize simplifies the problem of recognizing objects. This first (1) organization principle suggests that we analyze visual input by dividing a scene into figure and ground. OR we identify the main object in the scene (the figure), which stands out from the background. Second (2) Principle of proximity: Objects that are close together tend to be grouped together. The Principle of Similarity (3) states that similar stimuli are grouped together. Principle of continuity (4): Suggests that we assume that points that form smooth lines when connected probably belong together. Principle of simplicity (5): suggests that we will use the simplest solution to a perceptual problem. helps explain the "fun". Principle of Closure (6): we "fill in the blanks" to see a single object. P200

Optic Chiasm

The point at which the optic nerves cross the midline is known as the optic chiasm. named after the "X" shape Beyond the optic chiasm, the visual pathways are known as the optic tracts.

Sensation

The process of detection environmental stimuli or stimuli arising from the body. P181 This process brings information to the brain that arises in the reality outside of our bodies, like a beautiful sunset, originates from within, like an upset stomach. Sensory systems have developed through natural selection. Differences in sensation differ between person to person, such as corrective eye glasses. Sensation begins with the interaction between a physical stimulus and our biological sensory systems. P182

Gustation

The sense of Taste. P223

Audition

The sense of hearing. P209 High-amplitude waves are loud while Low are soft. in sound amplitude is measured in Decibels and frequency is measured in cycles per second aka Hertz. A wave with only one frequency is known as a pure tone, but these rarely occur in nature. BIOLOGY OF THE EAR: outer: Pinna collects and focuses sounds like a funnel and helps us localize sounds as being above or below the head. Sounds collected are channeled through the auditory canal, which ends at the tympanic membrane/ear drum at the boundary between the outer and middle ear. P210-211 Middle: The boundary between these two are formed by another membrane, the oval window. the gap between these is bridged by a series of tiny bones to transfer sound energy from the air to the middle ear in fluid in the inner ear. The water weakens the sounds. Without the adjustments from the small bones, we would lose a large amount of sound energy as the sound waves moved from air to liquid within the ear. Inner: Contains 2 sets of fluid-filled cavities embedded in the bone of the skull. one set is part of the vestibular system. The other set is the Cochlea (snail). it contains special receptor cells that respond to vibrations transmitted to the inner ear.

Olfaction

The sense of smell. P223 Immanuel Kant created "most dispensable" sense sense of smell has been influenced by humans walking on 2 feet rather than 4

Cochlea

The structure in the middle ear that contains auditory receptors. P211 contains specialized receptors that respond to vibrations transmitted to the inner ear. may be divided into 3 parallel chambers divided from one another by membranes. 2 of these chambers, the vestibular canal and the tympanic canal, are connected at the apex of the cochlea/ the point farthest from the oval window. P211 Cochlea duct is separated from the tympanic canal by the basil membrane.

Psychophysics

The study of relationships between physical qualities of stimuli and the subjective responses they produce. P184 Invented by Gustav Fechner. For studying the relationship between stimuli and the perception of those stimuli. The methods of psychophysics allow us to establish the limits of awareness, of thresholds, for each of our sensory systems. P185

Vestibular System

The system in the inner ear that provides information about body position and movement. P218 The proximity of these structures to the middle ear which can become congested due to illness is often responsible for those rather unpleasant feelings of dizziness that accompany an illness. P218 Receptors provide info about the position of the head relative to the ground, linear acceleration, and rotational movements of the head. like the Cochlea the receptors contain very sensitive hair cells that are bent back and forth within their surrounding fluid when the head moves. the movement of these hair cells result in the production of signals in the auditory nerve, the same nerve that carries info about sound. these axons form connections in the medulla and in the cerebellum which participates in balance and motor coordination, functions that are dependent on feedback about movements. medulla receives input from the visual system, the cerebellum, and other somatosenses. Medulla forms connections directly with the spinal cord, allowing us to adjust out posture in our to keep our balance. info travels from the medulla to the thalamus and then to the primary somatosensory cortex of the parietal lobe and to the primary motor cortex. P219 Pathway allows vestibular information to guide voluntary movement.

Sensory Adaption

The tendency to pay less attention to a non-changing source of stimulation. P183 In most cases we experience divided attention, in which we attempt to process multiple sources of sensory information. To prioritize input, we use selective attention, or the ability to focus on a subset of available information and exclude the rest.

Gate Theory

The theory that suggests that input from touch fibers competes with input from pain receptors, possibly preventing pain messages from reaching the brain. P221 Pain messages traveling to the brain may be modified by competing incoming sensory signals. Many of us spontaneously rub our elbow after bumping it painfully. gateway theory accounts for this phenomenon

Transduction

The translation of incoming sensory information into neural signals. P182 Before you can use information from your senses, it must be translated into a form the nervous system can understand (transduction).

Range of hearing

Ultrasounds are above the range of human hearing, and infrasounds are below the range of human hearing. P210

Fifth taste

Umami: meaning "savory" "meaty"

Developmental and individual differences in the chemical senses

Using facial expressions researchers have demonstrated that newborns differentiate among sweet, bitter, and sour tastes, but seem relatively oblivious to salty. P228 Overall number of taste buds decreases reducing the intensity of many tastes and proving a possible explanation for why some strong flavors such as that of broccoli are enjoyed much more by adults than by children. as we age our sensitivity to smell also decreases. Females are generally more sensitive to smell than males. The average person has about 6000 taste buds but this number varys. Supertasters have abnormal amounts of papillae and therefor have more tastebuds.

The visual stimulus

Visible light, or the light we can see, is a type of radiation emitted by the sun, other stars, and artificial sources such as the light bulb. P188 Light energies move in waves, like the ocean.

Where is that sound coming from?

We localize sound to the left and right by comparing the differences between the arrival times of the sounds to our two ears. P215

In both Olfaction and Gustation

We see 3 interesting perceptual themes 1. we can easily identify a number of very complex stimuli combining many types of molecules such as aroma of coffee 2. At the same time we can detect small differences between similar smells and tastes 3. our experience often shapes our perception of an olfactory of gustatory stimulus. P227

Primary Auditory cortex

conducts the first basic analysis of the wavelengths and amplitudes of incoming info. P212 surrounded by areas of secondary auditory cortex that respond to complex types of stimuli, like clicks, noise and sounds having particular patterns.

Midbrain

from the medulla, sound info is sent to the midbrain, which manages reflexive responses to sound. The midbrain participates in sound localization or the identification of a source of sound. passes info to the thalamus which sends sound info to the primary auditory cortex located in the temporal lobe. P212

Ultrasound (Audition)

occurs at frequencies above P210

Infrasound (audition)

refers to frequencies below the range of human hearing, or less than 20 Hz. P210 in humans however, this stimuli produces dizziness, nausea, uncontrolled bowel movements and other unpleasant symptoms and are under study as a possible means to nonlethal crowd control. P210

Optic Nerve

the nerve exiting the retina of the eye. P191 Axons from the final layer of cells leave the back of the eye to form the optic nerve. The point at which the optic nerves cross the midline is known as the optic chiasm

Perception

the process of interpreting sensory information. P181 Once information from the sensory systems has been transduced into neural signals and sent to the brain, the process of perception can begin. P183 Perception allows us to organize, recognize, and use the information provided by the senses. An important gateway to perception is is the process of attention, defined as a narrow focus of consciousness.

Vision

the sense that allows us to process reflected light. P188 The processing of light reflected from objects, is one of the most important sensory systems in humans.