Sensation and Perception
The Acoustic Signal
Created by air that is pushed up from the lungs past the vocal cords and into the vocal tract. The sound that is produced depends on the shape of the vocal tract as air is pushed through it
Monaural Cue
Depends on information from only one ear, this is how we judge elevation of sound
Perceiving Vibration
Pacinian corpuscle- A receptor with a distinctive elliptical shape associated with RA2 mechanoreceptors. It transmits pressure to the nerve fiber inside it only at the beginning or end of a pressure stimulus and is responsible for our perception of vibration and fine textures when moving the fingers over a surface -These fibers respond well to high rates of vibration but poorly to slow or constant pushing
The puzzle of olfactory quality
Similar molecular structure-Different odor Different molecular structure-similar odor
The Inner Ear
The innermost division of the ear, containing the cochlea and the receptors for hearing. Cochlea-the snail-shaped, liquid-filled structure that contains the structures of the inner ear, the most important of which are the basilar membrane, the tectorial membrane, and the hair cells.
Physiology of Depth Perception
There are neurons that signal different amounts of disparity: binocular depth cells or disparity-selective cells. Disparity tuning curve Neurons sensitive to absolute disparity first appear in the primary visual cortex, first place in the brain where information from both eyes converges. Neurons sensitive to relative disparity are primarily located in the brain regions along the ventral visual pathway *just read more about it in book
Pain in social situations
empathy, social rejection hurts, Tylenol can ease emotional pain -physical-social pain overlap hypothesis: proposes that pain resulting from negative social experiences is processed by some of the same neural circuitry that processes physical pain
Belt and Parabelt area (Auditory Cortex)
-"higher up" -neurons require increasingly complicated stimuli to activate (complex sounds, speech, etc.) -If you think of A1 being similar to V1, these areas of higher processing are similar to those in vision.
Perceiving Texture
-David Katz-duplex theory of texture perception-states that our perception of texture depends on both spatial cues and temporal cues -Spatial cues-provided by relatively large surface elements, such as bumps and grooves, that can be felt both when the skin moves across the surface elements and when it is pressed onto the elements Temporal cues-occur when the skin moves across a textured surface like fine sandpaper. This type of cue provides information in the form of vibrations that occur as a result of the movement over the surface -Selective adaptation procedure-pictures on phone
Physiology of Auditory Localization
-Interaural Time Differences -Narrowly tuned neurons- neurons in the superior olivary nuclei and the inferior colliculus respond to a narrow range of ITD's (coincidence detectors) **Specificity coding -Broadly tuned neurons- neurons in the superior olivary nuclei in mammals are broadly tuned **distributed coding -Interaural Level Differences -Neurons in the Lateral Superior Olive (LSO) appear to be first site of extraction of ILD's -Sensitive to about 1 dB difference (Comparable to ILD thresholds in humans and cats)
Miller and Isard
-Meaningfulness makes it easier to perceive spoken words -Created three kinds of stimuli: 1. normal grammatical sentences 2. anomalous sentences that follow the rules of grammar but make no sense 3. ungrammatical strings of words (Gadgets simplify work around the house, Gadgets kill passengers from the eyes, Between gadgets highways passengers the steal) Shadowing-presented these sentences to subjects through earphones and asked them to repeat out loud what they were hearing Accuracy in order: 89%, 79%, 56%
Pain Perception
-Nociceptive pain is pain caused by the activation of receptors in the skin called nociceptors, which are specialized to respond to tissue damage or potential damage. Spinothalamic pathway to the brain. -Direct Pathway Model of Pain- pain occurs when nociceptor receptors in the skin are stimulated and send their signals directly from the skin to the brain -the Gate Control Model-idea that perception of pain is controlled by a neural circuit that takes into account the relative amount of activity in nociceptors, mechanoreceptors, and central signals. This model has been used to explain how pain can be influenced by factors other than stimulation of receptors in the skin. -Needed to be updated because there are situations in which pain is affected by factors in addition to stimulation of the skin
Cognition and pain
-People who were told what to expect and told to relax requested less painkillers than those who did not receive this information. People have also gotten relief from taking a placebo. Negative expectation increased activity in the hippocampus -Attention-pain sometimes doesn't occur until the person realizes they are injured. A way to decrease pain is to distract the person's attention from the source of pain. -Emotions- positive emotions are associated with decreased pain. (looking at pictures and listening to music)
Speech Segmentation
-the perception of individual words in a conversation -Saffran-demonstrated statistical learning in young infants. The transitional probabilities between two syllables that appeared within a word was always 1.0. The transitional probabilities between the end of one word and the beginning of another was only 0.33. Transitional probabilities- the chances that one sound will follow another sound
Binaural cues
-use information reaching both ears to determine the left-right position of sounds -Interaural Level Difference (ILD)-is based on the difference in the sound pressure level of the sound reaching two ears. A difference in level between the two ears occurs because the head is a barrier that creates and acoustic shadow, reducing the intensity of sounds that reach the far ear. This reduction of intensity at the far ear occurs for HIGH-frequency sounds. -Interaural Time Difference (ITD)- the time difference between when a sound reaches the left ear and when it reaches the right. The ITD is zero if the source is directly in front of the listener and the distance to each ear is the same. Can be used to determine a sound's location. Most effective for determining the locations of low-frequency sounds.
Core Area (Auditory Cortex)
-where info first comes into cortex -activated by simple sounds (pure tones) -tonotopic map-neurons are laid out in order of response to frequency
Pathway to Auditory Cortex
1. Cochlea: info leaves via auditory nerve 2. Cochlear nucleus: brain stem 3. Superior olivary nucleus (brain stem)-convergence from both ears-involved in sound localization 4. Inferior colliculus: midbrain 5. Medial geniculate nucleus (thalamus) 6. Auditory cortex or A1 (temporal lobe) *All laid out in tonotopic map Acronym: SONIC MG
Experience-dependent plasticity
A process by which neurons adapt to the specific environment within which a person or animal lives. This is achieved when neurons change their response properties so they become tuned to respond best to stimuli that have been repeatedly experienced in the environment.
The Middle Ear
A small cavity, about 2 cubic centimeters in volume, that separates the outer and inner ears. This cavity contains the ossicles, the three smallest bones in the body. The malleus is set into vibration by the tympanic membrane, to which it is attached. The vibrations are then transmitted to the incus, and then to the stapes. The stapes then transmits its vibrations to the inner ear by pushing on the membrane covering the oval window. The ossicles are necessary because without them less than 1% of the vibrations would be transmitted.
Frequency theory/temporal coding
According to the frequency theory of hearing, the frequency of the auditory nerve's impulses corresponds to the frequency of a tone, which allows us to detect its pitch. Sounds come into the ear as acoustical signals and are later transformed into nerve impulses by the cochlea. When precise spike timing or high-frequency firing-rate fluctuations are found to carry information, the neural code is often identified as a temporal code.
Wernicke's aphasia
An inability to comprehend words or arrange sounds into coherent speech, caused by damage to Wernicke's area
Activating ORN's
An odorant shows a pattern of activation of the ORN's-an odorant's Recognition Profile -So, molecules with similar structures can smell different b/c they have different recognition profiles eg: octanoic acid and octanol differ by one oxygen molecule, octanol is described as "rose", "sweet", and "fresh" while octanoic acid is described as "rancid", "sour", and "repulsive" -Axons of ORNs pass through bony structure called cribiform plate and bundle to form olfactory nerve. -Olfactory nerve enters olfactory bulb
The Skin
Epidermis: The outer layers of the skin, including a layer of dead skin cells Dermis: The layer of skin below the epidermis Mechanoreceptors: receptor that responds to mechanical stimulation of the skin, such as pressure, stretching, or vibration --Merkel receptor: a disk-shaped receptor in the skin associated with slowly adapting fibers and the perception of fine details (fires continuously-slowly adapting (SA) fiber) ---details, shape, texture --Meissner corpuscle: a receptor in the skin, associated with RA1 mechanoreceptors. It has been proposed that the Meissner corpuscle is important for perceiving tactile slip and for controlling the force needed to grip objects (fires only when the stimulus is first applied and then removed-rapidly adapting (RA) fiber) ---controlling hand grip and perceiving motion across skin
Range of hearing
Experiments have shown that a healthy young person hears all sound frequencies from approximately 20 to 20,000 hertz." "The maximum range of human hearing includes sound frequencies from about 15 to about 18,000 waves, or cycles, per second." "The general range of hearing for young people is 20 Hz to 20 kHz.
the somatosensory cortex
From the thalamus, signals travel here. Organized into maps that correspond to locations on the body. An area in the parietal lobe that receives inputs from the skin and the viscera associated with somatic senses such as touch, temperature, and pain.
Olfactory bulb:
Glomeruli-small structures in the olfactory bulb that receive signals from similar olfactory receptor neurons. One function of each glomerulus is to collect information about a small group of odorants. Olfactory bulb: the structure that receives signals directly from the olfactory receptors. The olfactory bulb contains glomeruli which receive this signals from the receptors -Powerpoint notes about olfactory bulb!
Perceiving Objects
Haptic perception- perception in which three-dimensional objects are explored with the fingers and hand 1. The sensory system: involved in detecting cutaneous sensations such as touch, temperature, and texture and the movements and positions of your fingers and hands 2. The motor system: involved in moving your fingers and hands 3. Cognitive system: Involved in thinking about the information provided by the sensory and motor systems -Cortical neurons are specialized -Cortical responding is affected by attention -Cortical responding can occur while watching touching (read the physiological things again, p.350)
Bekesy's Place Theory of Hearing
He observed the vibration of the basilar membrane by boring a hole in cochleas taken from animal and human cadavers. He presented different frequencies of sound and observed the membrane's vibration by using a technique similar to that used to create stop-action photographs of high-speed events. When he observed the membrane's position at different points in time, he saw that the basilar membrane's vibrations as a traveling wave, like the motion that occurs when a person holds the end of a rope and "snaps" it, sending a wave traveling down the rope.
Speech Formant
Horizontal band of energy in the speech spectrogram associated with vowels Formant transition: in the speech stimulus, the rapid shift in frequency that precedes a formant -Each vowel sound has a characteristic series of formants. The first formant has the lowest frequency; the second formant is the next highest; and so on.
The representation of pitch in the brain
How the basilar membrane vibrates to different frequencies
Perceiving Details
How the fiber associated with a Merkel receptor fires in response to a grooved stimulus pushed into the skin. -Better acuity is associated with less spacing between the Merkel receptors. -Although tactile acuity is better on the tip of the index finger than on the tip of the little finger, the spacing between Merkel receptors is the same on all the fingertips. -The small receptive fields of neurons receiving signals from the fingers translates into more separation on the cortex, which enhances the ability to feel two close-together points on the skin as two separate points.
Onset
If two sounds start at slightly different times, it is likely that they came from different sources. This occurs often in the environment because sounds from different sources rarely start at exactly the same time.
McGurk Effect
Illustrates that although auditory information is the major source of information for speech perception, visual information can also exert a strong influence on what we hear
Pitch
Involves differences in the low to high quality of sound, illustrated by what we hear playing notes from left to right on a piano
Information from our knowledge of language
It is easier to perceive phonemes that appear in a meaningful context. Richard Warren demonstrated this by having participants listen to a recording of the sentence "The state governors met with their respective legislatures convening in the capital city." Warren replaced the first /s/ in legislatures with the sound of a cough and told his subjects that they should indicate where in the sentence the cough occurred. None identified the correct position of the cough, and none noticed that the s in legislatures was missing. This effect (phonemic restoration effect) was experienced even by students and staff who knew the s was missing. Phonemic restoration effect- an effect that occurs in speech perception when listeners perceive a phoneme in a word even though the acoustic signal of that phoneme is obscured by another sound, such as white noise or a cough.
Broca's aphasia
Language problems including labored and stilted speech and short sentences, caused by damage to Broca's area in the frontal lobe
the homunculus
Latin for "little man", the resulting body map. Shows that adjacent areas of the skin project to adjacent areas in the brain, and that some areas on the skin are represented by a disproportionately large area of the brain.
Complex tone
Made up of a number of pure tone (sine-wave) components added together. Each of these components is called a harmonic of the tone
The Holway and Boring Experiment
Observers in Holway and Boring's experiment sat in the intersection of two hallways and saw a luminous test circle when looking down the right hallway, and a luminous comparison circle when looking down the left hallway. The comparison circle was always 10 feet from the observer, but the test circles were presented at distances ranging from 10 feet to 120 feet. An important property of the fixed-in-place comparison circle was that its size could be adjusted. The observer's task on each trial was to adjust the diameter of the comparison circle in the left corridor to match his or her perception of the sizes of the various test circles presented in the right corridor. -Because objects with the same visual angle create the same-sized image on the retina, all of the test circles had the same-sized image on the observers retinas, no matter where in the hallway they were located *read more about it
cortical magnification
Occurs when a disproportionately large area on the cortex is activated by stimulation of a small area on the receptor surface. One example of cortical magnification is the relatively large area of visual cortex that is activated by stimulation of the fovea. An example in the somatosensory system is the large area of somatosensory cortex activated by stimulation of the lips and fingers.
Pure tone
Occurs when changes in air pressure occur in a pattern described by a mathematical function called a sine wave (whistling high pitched notes, flute, tuning forks, etc)
Categorical Perception
Occurs when stimuli that exist along a continuum are perceived as divided into discrete categories. Voice Onset Time- the time delay between when a sound begins and when the vocal cords start vibrating
Size Constancy
Occurs when the size of an object is perceived to remain the same even when it is viewed from different distances -Even though our images on people's retinas become half as large when we double our distance,we do not appear to shrink and still appear to be our normal size
The Neural Code for Olfactory Quality
Olfactory Mucosa-Located in the upper region of the nasal cavity -Made up of olfactory epithelium (the retina of the nose) and underlying tissue, blood vessels, glands, and bundles of fine axons from Olfactory Neurons -Protects the olfactory epithelium and allows odors to dissolve so that they can be detected by Olfactory Receptor Neurons
Aspects of Sound
Sound is pressure changes in the air. Condensation: when the surrounding air molecules are pushed together, causing a slight increase in the density of molecules near the diaphragm. Rarefaction: Air molecules spread out to fill in the increased space, the decreased density of air molecules caused by rarefaction causes a slight decrease in air pressure Sound wave-the changing pattern of air pressure
The Outer Ear
Sound waves first pass through here, which consists of the pinnae, the structures that stick out from the sides of the head, and the auditory canal, a tubelike recess about 3 cm long in adults. Auditory canal protects the middle ear, along with its wax. Regulates temperature. Resonance occurs in the auditory canal when sound waves that are reflected back from the closed end of the auditory canal interact with sound waves that are entering the canal. Slight amplifying effect that increases the sound pressure level of frequencies
Timbre and Pitch
Sounds that have the same timbre or pitch range are often produced by the same source. (A flute doesn't suddenly start sounding like the timbre of a trombone)
Proximity in Time
Sounds that occur in rapid succession usually come from the same source
Auditory Continuity
Sounds that stay constant or that change smoothly are often produced by the same source.
Information Provided By The Face
Speech perception is multimodal; that is, our perception of speech can be influenced by information from a number of different senses. (matching lip movements fa-fa, as someone mouths ba-ba)
Variability between phonemes and acoustic signal
The acoustic signal associated with a phoneme changes depending on its context. Phoneme-the shortest segment of speech that, if changed, would change the meaning of a word The context in which a specific phoneme occurs can influence the acoustic signal that is associated with that phoneme Variability from different speakers-people say the same words in a variety of different ways, so a particular phoneme or word can have very different acoustic signals *Read more into this one
Relative Disparity
The difference in absolute disparities of two elements in the visual scene
Experience/Familiarity
The effect of past experience on the perceptual grouping of auditory stimuli can be demonstrated by presenting the melody of a familiar song. Melody Schema-a representation of a familiar melody that is stored in a person's memory
Timbre
The quality that distinguishes between two tones that have the same loudness, pitch, and duration, but still sound different. When a flute and an oboe play the same note with the same loudness, we can still tell the difference between the two instruments.
Olfactory Receptor Neurons (ORN's)
These are like rods and cones of the retina in a number of ways (a) contain molecules sensitive to odorants like rods and cones contain visual pigment molecules (b) made up of proteins that cross the membrane of the receptor neuron 7 times (c) sensitive to a range of specific stimuli -while there are rods and three types of cones, there are 350 types of ORN's (1000 different types in mice)
Ventral Streams
WHAT identifies sounds
Dorsal Streams
WHERE localizes sounds
Sound spectrogram
What do the axes represent?-Frequency is indicated on the vertical axis and time on the horizontal axis What are the dark bands?- the dark bands indicate intensity; the darker they are the greater the intensity What are formant transitions?-the rapid shift in frequency that proceeds a formant
Location
You can separate sounds based on localization cues such as ILD and ITD. When two sounds are separated in space, the cue of location helps us separate them perceptually. In addition, when a source moves, it typically follows a continuous path rather than jumping erratically from one place to another. (helps us perceive the motion of a passing car)
Horopter
a line or surface containing all those points in space whose images fall on corresponding points of the retinas of the two eyes. a 3D curve that can be defined as the set of points for which the light falls on corresponding areas in the two retinas -points nearer to horopter have crossed disparity -points farther than the horopter have uncrossed disparity
medial lemniscal pathway
a pathway in the spinal cord that transmits signals from the skin toward the thalamus
Random-dot stereograms
is stereo pair of images of random dots which when viewed with the aid of a stereoscope, or with the eyes focused on a point in front of or behind the images, produces a sensation of depth, with objects appearing to be in front of or behind the display level. Julesz-wanted to show that observers can perceive depth in displays that contain no depth information other than disparity
The Brain and Pain
multimodal nature of pain-the fact that the experience of pain has both sensory and emotional components sensory component of pain- pain perception described with terms such as prickly, throbbing, hot, or dull. affective (emotional) component of pain- the emotional experience associated with pain described as torturing, annoying, frightful, or sickening chemical components-opioids-a chemical such as opium, heroin, and other molecules with related structures that reduce pain and induce feelings of euphoria. -naloxone-a substance that inhibits the activity of opiates. It is hypothesized that naloxone also inhibits the activity of endorphins and therefore can have an effect on pain perception -endorphins-chemical that is naturally produced in the brain and that causes analgesia
Detecting Odors
olfaction-the sense of smell detection threshold: the lowest concentration at which an odorant can be detected forced-choice method: method in which two choices are given, and the subject has to pick one. For example, a subject is presented with a weak odorant at one trial, and no odorant on another trial, and has to pick the trial on which the odorant was presented. olfactometer: an instrument used to detect and measure odor dilution. Olfactometers are used in conjunction with human subjects in laboratory settings, most often in market research, to quantify and qualify human olfaction.[1] Olfactometers are used to gauge the odor detection threshold of substances. To measure intensity, olfactometers introduce an odorous gas as a baseline against which other odors are compared.
spinothalamic pathway
one of the nerve pathways in the spinal cord that conducts nerve impulses from the skin to the somatosensory area of the thalamus
indirect sound
reaches your ears after bouncing off walls, ceiling, floor (inside)
Identifying odors
recognition threshold- concentration increased by as much as a factor of 3 above detection threshold. Humans can detect as many as 100,000 different odors, but recognizing them is more difficult. Memory of odor is what is at fault for this.
Binocular Disparity
refers to the difference in image location of an object seen by the left and right eyes, resulting from the eyes' horizontal separation (parallax). The brain uses binocular disparity to extract depth information from the two-dimensional retinal images in stereopsis.
Absolute Disparity
refers to the visual angle between the images of an object on the two retinas. When images of an object fall on corresponding points, the angle of disparity is zero. When images fall on noncorresponding points, the angle of disparity indicates the degree of noncorrespondence.
direct sound
sound that reaches your ears directly (outside)
Visual Angle
the angle of an object relative to the observer's eye. The visual angle depends on both the size of the stimulus and its distance from the observer. When the person moves closer, the visual angle becomes larger. (Taking a pic of holding the Eiffel Tower, the visual angle between the two fingers is the same as the visual angle of the Eiffel Tower)
Loudness
the perceptual quality most closely related to the level or amplitude of an auditory stimulus, which is expressed in decibels. (difference between shout and whisper)
The correspondence problem
the problem faced by the visual system, which must determine which parts of the images in the left and right eyes correspond to one another. Another way of stating the problem is: How does the visual system match up the images in the two eyes? This matching of the images is involved in determining depth perception using the cue of binocular disparity.
Architectural acoustics
the study of how sounds are reflected in rooms. Reverberation time- the time it takes for the sound to decrease to 1/1000th of its original pressure (or a decrease in level by 60 dB) If the reverberation time is too long such as in large cathedrals it creates echoes.
precedence effect
when two identical or very similar sounds reach a listener's ears separated by a time interval of less than about 50 to 100 ms, the listener hears the first sound that reaches his or her ears