the initial process of detecting and encoding environmental energy
the process of organzing and iterpreting sensations into meaningful experiences
smallest amount of stimulus energy necessary for an observer to reliably detect a stimulus
Doctrine of Specific Nerve Energies
the quality of the sensation elicited by a stimulus depends primarily on the nerve stimulated and only secondarily on the stimulus itself
the region on the receptor surface that, when stimulated, influences the firing rate of the cell
refers to increased intensity difference observed on either side of a dark-light broder
deficit in which the subjects visual accuity is normal but their shape perception is distorted
deficit in which subject has no distortion in shape percetption but still cannot recognize objects
properties of a 2D image that, in general, do not change as a viewer's perspective of an object changes
inability to recognize faces
Inverse Optics Problem
refers to the fact that any 2D image can be created by an infinite number of 3D environments
as one moves through the environment, nearer stationary objects appear to move faster than further stationary objects
imaginary arc passing through point of fixation; objects on horopter fall on corresponding points on the two retinas
the retinal image on the two eyes is slightly different and this difference provides an absolute depth cue
two lights blinking on and off will, at the proper frequency, appear to be one light that is moving
a period of neural plasiticity when certain environmental stimuli must be present for normal brain development to occur
pressure changes in a medium that can be detected by auditory organs
Cone of Confusion
the set of all points that could produce a particular time and intensity difference between the two ears
if someone says Ba, but they're moth movements are those of Ga, then Da is perceived
Phonemic Restoration Effect
auditory system fills in phonemes that are obscured by noise
the shortest segment of speech that, if changed, would change the meaning of a word
after being rotated, people experience paradoxical motion, in which the world seems to be spinning but visually remains in the same place
a reflexive eye movement that begins when the vestibular organs signal rotation about the body axis
skin temperature at which no thermal sesations are elicited
naturally occuring opiate-like chemcials that suppress pain
Common Chemical Sense
sensory system that responds to chemical irritants
inability to detect certain smells
chemicals released by one animal that cause behavioral reactions in other animals of the species
women who live together eventually have menstrual periods that all begin at approximately the same time
Method of Constant Stimuli
a number of stimulus intensities are selected beforehand by researcher. the stimuli are presented numerous times in random order and subject reports whether each stimulus is detected. a graph is plotted showing percentage detected as a function of stimulus intensity. the point at which stimulus was detected 50% of the time is absolute threshold.
Method of Limits
researcher starts with stimulus clearly above threshold and asks subject if they can detect it. researcher adjusts stimulus intensity down in fixed increment until subject cannot detect it. process repeated several times, sometimes ascending, sometimes descending. crossover point is deemed absolute threshold.
Method of Adjustment
the intensity of stimulus is adjusted by observer until they can just barely detect it
What are the two problems common to all three of Fechner's methods for determining absolute threshold?
- Observers' criteria for responding greatly affect the results
- The observer could be lying
What are the four main parts of the neuron and their functions?
- Soma: contains nucleus of cell and provides for the life processes
- Axon: transmits information from cell body to terminal buttons
- Dendrites: receive messages from other neurons
- Terminal Buttons: pass information to next neuron in the chain
What occurs during an action potential?
What is the significance of the Werner and Mountcastle experiment?
showed that perceived magnitude is due to firing rate of sensory neurons
What is the function of the cornea?
primary refractive surface of the eye
What is the function of the iris?
can change size of pupil to control amount of light entering eye
What is the function of the lens?
allows adjustments in focus of eye
How does image formation differ between the lens system and a pinhole camera system? What is the advantages and disadvantages of each?
- Lens System: focuses many light rays on a single point
- Advantage: image is very bright
- Disadvantage: can be out of focus
- Pinhole Camera: uses very small hole to allow very small number of light rays from each point in the visual field to enter
- Advantage: never out of focus
- Disadvantage: image is very dim
Compare and contrast the rods and cones
- Sensitive to Light
- Many Rods
- Many connect to each bipolar cell
- Pigment is relatively insensitive to wavelength
- Found only in the periphery
- Pigment regenerates in 30 min.Cones:
- Less sensitive
- Few connect to each bipolar cell
- Have differential sensitivities to wavelength
- Concentrated in Fovea
- Pigment regenerates in 6 min.
Diagram the response of on-center, off-surround cell to a) diffuse illumination. b) illumination only of the center, and c) illumination only of the surround.
What is the function of the three types of ganglion cell?
- P Cells: color and form perception
- M Cells: motion perception, depth perception, simple detection of light
- K Cells: code overall level of illumination
What are the three types of cells found in V1 and what stimuli to they respond to?
- Simple Cells: bars in a particular location of a particular orientation
- Complex Cells: bars in a particular location of a particular orientation that are moving in a particular direcction
- End-Stopped Cells: bars in a particular location of a particular orientation and particular length
Explain the Young-Helmoltz theory of color perception
there are three different types of color receptor, each responding maximally to a different wavelength, but having some response to every wavelength
Explain the Hering Opponent Process theory of color perception
there are three different types of color receptor that respond to pairs of colors (red-green, blue-yellow, black-white). each receptor is excited by one of the pair and inhibited by the other
How were the two theories of color perception resolved?
the cones respond as the Young-Helmholtz theory predicts while ganglion cells respond as the Herring Opponent Process theory predicts
How do people with dichromatism and anomalous trichromatism perform relative to normals in color matching experiments?
- Dichromatism: need only two colors to match the pure wavelength light, but their match would not look correct to normals
- Anomalous Trichromatism: need three colors to match the pure wavelength light, but their match would not look correct to normals
Why is the lateral inhibition which creates Mach Bands important?
Explain procedure, results and significance of the Ungerlieder and Mishkin experiments
- Procedure: researchers ablated cells of interior temporal lobe in one group of monkeys and the posterior parietal lobe in another group of monkeys. monkeys were then trained to do an object recognition task, as well as an object location task
- Results: monkeys with IT ablated cells could not perform the object recognition task, but could perform the object location task. monkeys with PP ablated cells showed reciprocal results.
- Significance: the IT (ventral) pathway codes identity of an object. The PP (dorsal) pathway codes location of an object
What are the steps in the object recognition process according to Biederman's RBC theory?
- 1. Edges are extracted from an image.
- 2. Image edges are parsed into parts and non-accidental properties are determined.
- 3. The identity of the geons is determined.
- 4. The relations among the geons are determined.
- 5. The best match in memory is found.
What are the four classes of depth cues?
- Motion Produced
- Binocular Disparity
What does it tell you about the location of an object if its retinal image in the two eyes is inwardly displaced, outwardly displaced, or correspoding?
- Inwardly Displaced: object is closer than the horopter
- Outwardly Displace: object is further than the horopter
- Corresponding: object is on the horopter
What are the two causes of stereo blindness?
- Infantile Strabismus: the eyes did not have coordinated movement during infancy and thus disperity-tuned cells never developed
- Genetic Disorder
What three pieces of evidence suggest that stereo vision is not particularly important to normal perception?
- People who are stereoblind often don't realize it
- Stereo vision is not useful at long distances
- Stereo vision does not aid in identifying an object
Explain the Angle of Regard Theory
objects appear smaller when the head is tilted up than when held parallel to the ground
Explain the Apparent Distance theory
earth's terrain causes the moon to appear further away and thus bigger at the horizon
What are the causes of the Phi Effect and the Autokinetic Effect?
- Phi Effect: cells some distance apart on the retina can be wired to excite another cell (indicating motion in a particular direction) when they are stimulated with a particular delay between them. the Phi Effect simulates this pattern of stimulation
- Autokinetic Effect: to compensate for muscular fatigue, the eyes require abnormally strong signals from the brain. these abnormal signals are the same as would be required to track a moving object so the brain assumes the light is moving
What is the cause of the Poggendorf Illusion?
blur by the optic media, lateral inhibition in the retina and processing strategies all affect this illusion
What is the cause of the Wundt-Hering Illusion?
a large number of small Poggendorf Illusions
What is the cause of the Ponzo Illusion?
linear perspective and texture gradients make the top bar appear further away and thus bigger than the bottom bar
What is the cause of the Ames Window Illusion?
the image on the retina is consistent with both a trapezoidal window rotating completely and a rectangular window switching directions every 180. since we are used to seeing rectangular windows, our visual system prefers this interpretation
What is the anatomical cause of myopia, hypermetropia, astigmatism, and presbyopia?
- Myopia: eyeball is too short
- Hypermetropia: eyeball is too long
- Astigmatism: lack of spherical cornea
- Presbyopia: weakening of ciliary muscles and hardening of the lens
What do the numerator and denominator in the lines of an eyechart mean?
- Numerator: distance, in feet, at which the test was administered
- Denomenator: distance, in feet, at which the critical feature of the test symbol covers one minute of visual angle
What is the cause and treatment of Cataracts?
- 1. congenital and inherited at birth
- 2. acquired by injury or disease
- 3. old age
- Treatment: artificial lens implants or removing the lens and using spectacles to correct vision
What is the cause and treatment of Detatched Retina?
- Cause: photoreceptors become detatched from the pigment epitheliam
- Treatment: cryotherapy-eye is purposefully injured to create scar tissue that locks retina into place
What is the cause and treatment of Glaucoma?
- Cause: problems draining the aqueous humor cause an increase in intraocular pressure. the increased pressure compresses the blood vessels serving the optic nerve and the optic nerve fibers die
- Treatment: drugs are available that decrease the production of aqueous humor or remove blockage
What are the units for measuring sound frequency and amplitude?
- Frequency: Hertz (Hz)
- Amplitude: Decibels (dB)
What are the psychological correlates of frequency and amplitude?
- Frequency: pitch
- Amplitude: loudness
List the three structures of the outer ear.
- Tympanic Membrane
What two functions do the ossicles serve?
- Amplify vibrations from the tympanic membrane
- Protect the ear from loud sounds
Explain von Bekesy's Place theory of pitch perception.
different places on the basilar membrane vibrate in response to different frequencies. the hair cells being stimulated by the region with the greatest amount of vibration indicate the frequency that is present
Explain Rutherford's Frequency theory of pitch perception
the basilar membrane vibrates at the same frequency as the stimulus. every time the basilar membrane vibrates, it causes an action potential in the Auditory Nerve. Thus, the rate at which the auditory nerve fires codes the frequency of the stimulus
How was the conflict between the two theories of pitch perception resolved?
below 1000 Hz, firing rate determines pitch (Rutherford). above 5000 Hz, place of greatest basilar membrane stimulation determines pitch (von Bekesy). between 1000 and 5000 Hz, both mechanisms operate
When two tones are presented simultaneoulsy, what is perceived if a) the tones are separated by 1-15 Hz, b) the tones are separated by more than 15 Hz but less than the critical bandwidth, c) the tones are separated by the critical bandwidth?
- 1 to 15 Hz: a tone midway in frequency between the two tones is perceived that ossilates in loudness at the same frequency as the difference between the two tones
- 15 Hz: a tone midway in frequency between the tones is perceived that sounds rough
- Critical Bandwidth: two separate tones are perceived
List the two monaural cues for localizing sound.
List the two binaural cues for localizing sound.
- Interocular Intensity Difference
- Interocular Time Difference
When is the interaural intensity difference most effective for localizing sound?
high frequency sounds
How can we overcome the Cone of Confusion?
by moving our head
What are three pieces of evidence that speech perception is "special" relative to perception of other sounds?
- 1. Speech is perceived more categorically than other sounds
- 2. Visual stimulation effects speech perception
- 3. Top-Down information affects speech perception
Describe the similarities between the speech and object recognition processes.
In speech recogntion, a few phonetic features (non-accidental properties in object recognition) combine to create phonemes (geons). Then phonemes, in their proper relations, are used to recognize words (objects).
What is the function of the semi-circular canals?
register the direction and extent of rotary acceleration
What causes motion sickness?
dissociation between visual and vestibular information
What evolutionary purpose does motion sickness serve?
prevents food poisoning, which causes dissociatin between vestibular system and vision
What are three causes of the differential sensitivity of various body parts to touch?
- 1. Sensitive areas have a higher density of pressure sensitive neurons
- 2. Receptors in more sensitive areas have smaller receptive fields than those in less sensitive areas
- 3. Sensitive areas receive relatively more area in the somatosensory cortex
What two health problems do people with congenital analgesia commonly experience?
- severe childhood injuries
- massive injuries to their joints
Draw a diagram of the neural circuit for pain according to Spinal Gate control theory
To what sort of stimuli do the S fibers and L fibers in the pain perception system respond?
- S fibers: sustained (aching) pain
- L fibers: sharp pain and pressure
How do endorphins reduce pain?
stimulate L fibers
What are the limits of temperature adaptation?
61-108 F (in water)
What is paradoxical cold?
a very warm stimulus can elicit a cold sensation when applied to an area of the skin that has no warm receptors
Where can receptors for the common chemical sense be found?
Oral cavity, nasal cavity, and cornea
What is the chief problem with studying smell?
no adequate system of describing smells
Explain the stereochemical theory of odor perception
olfactory receptors respond to molecules of a particular shape and size
What are two problems with the stereochemical theory of odor perception?
- 1. Each olfactory cell responds to chemicals of a variety of shapes and sizes
- 2. the relationship between molecule shape and odor is not as strong as the theory predicts
Explain how odor quality is coded according to chromatographic theory.
different chemicals spread accross the mucosa in different ways. the regions of the mucosa the chemical is activating can therefore be used as a code for odor quality.
What is the significance of the Engen and Ross experiment?
smells appear to be difficult to learn but easy to remember
What are the four primary tastes? What chemical produces each? What is the evolutionary function of each?
- Sweet: complex organic molecules, sweet foods provide energy
- Salt: simple inorganic molecules that are not acids or bases, detects sodium
- Sour: substances containing acids, bacterial decomposition
- Bitter: alkaloid substances, poison detector
Where can the taste buds be found?
tongue, inner cheeks, throat and palate
How do taste cells respond to the four primary tastes?
respond somewhat to all 4 primary tastes, but respond with preferential vigor to one
What effects do MSG and sodium lauryl sulfate have on taste perception?
- MSG: increases sensitivity to both salt and sweet
- Sodium Lauryl Sulfate: decrease sweet sensitivity, increase bitter sensitivity
How does aging effect our perception of flavor?
smell deteriorates before taste; sensitivity to salt and sweet decrease more than sensitivity to sour and bitter. foods with a pleasant smell, but bitter taste are less enjoyable
At what temperature range is sensitivity for food greatest?