Sensation and Perception Ch 1 and 2

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Response compression: as intensity increases, the perceived magnitude increases more SLOWLY or LESS than than the intensity
Dark-adapted sensitivity: The sensitivity of the eye after it has completely adapted to the dark.
Rod-cone break: The point on the dark adaptation curve at which vision shifts from cone vision to rod vision.
cones spectral sensitivity: more sensitive to medium wavelength light at 560 nm (yellowish); most sensitive to yellow but will still react to other colors
Blind spot: The small area where the optic nerve leaves the back of the eye; there are no visual receptors in this area so small images falling directly on the blind spot cannot be seen.
Bottom-up processing: Processing in which a person constructs a perception by analyzing the information falling on the receptors. Also called data-based processing.
cerebral cortex: outermost area of the brain ("gray matter") comprised of cell bodies of neurons; where you "experience" everything
Agnosia: The inability to recognize objects.
concentration gradient: difference in distribution for various ions between the inside and outside of the membrane
cones converging circuit: in cones in peripheral retina; 6 cones converging on ganglion cell; good at light sensitivity
Neural processing: Operations that transform electrical signals within a network of neurons or that transform the response of individual neurons.
afferent: brings info into a structure
parietal lobe: tactile senses (touch)
Dark adaptation: Visual adaptation that occurs in the dark, during which the sensitivity to light increases. This increase in sensitivity is associated with regeneration of the rod and cone visual pigments.
Purkinje shift: The shift from cone spectral sensitivity to rod spectral sensitivity that takes place during dark adaptation. See also Spectral sensitivity.
Nerve: A group of nerve fibers traveling together.
Spectral sensitivity: The sensitivity of visual receptors to different parts of the visible spectrum. See also Spectral sensitivity curve.
depolarization: if sodium came pouring into the cell (decreases the amount of negativity); action potential or graded potential
bipolar or unipolar neurons: sensory
Nerve impulse: The rapid increase in positive charge that travels down the nerve fiber. Also called the action potential.
rods spectral sensitivity: most sensitivity at short wavelength light at 500 nm (like a green)
Receptor: specialized neuron that transduces energy into an electrical impulse that the brain can understand
Power function: A mathematical function of the form P = KSn, where P is perceived magnitude, K is a constant, S is the stimulus intensity, and n is an exponent.
Visual pigment molecules: Light-sensitive molecules in the outer segments of the rod and cone visual receptors that are responsible for the transformation of light energy into electrical energy. The molecule consists of a large protein component called opsin and a small light-sensitive component called retinal.
occipital lobe: vision
temporal and frontal lobes: gustatory (taste) and olfaction (smell)
Spectral sensitivity curve: The function relating a subject's sensitivity to light to the wavelength of the light. The spectral sensitivity curves for rod and cone vision indicates that the rods and cones are maximally sensitive at 500nm and 560nm, respectively. See also Purkinje shift.
Inhibitory response: The response of a nerve fiber in which the firing rate decreases due to inhibition from another neuron.
Retinitis pigmentosa: A retinal disease that causes a gradual loss of vision.
1ms: refractory period
muscular schlerosis: the myelin gets destroyed and the whole neuron dies
Doctrine of specific nerve energies: A principle proposed by Mueller, which states that our perceptions depend on "nerve energies" reaching the brain and that the specific quality we experience depends on which nerves are stimulated. For example, activating the optic nerve results in seeing, and activating the auditory nerve results in hearing.
method of limits: A psychophysical method for measuring threshold in which the experimenter presents stimuli in alternating ascending and descending order.
linear circuits: found in fovea; 1 cone to 1 ganglion cell; good with visual acuity
Visual pigment: A light-sensitive molecule contained in the rod and cone outer segments. The reaction of this molecule to light results in the generation of an electrical response in the receptors.
Axon: The part of the neuron that conducts nerve impulses over distances. Also called the nerve fiber.
Environmental stimulus: All of the things in our environment that we can potentially perceive at a given point in time.
Detached retina: A condition in which the retina is detached from the back of the eye.
electrical gradient: the difference in positive and negative charges across the membrane
retinal: a light sensitive molecule; component of visual pigment molecules
Peripheral retina: All of the retina except the fovea and a small area surrounding the fovea.
presynaptic terminals: where the neurotransmitter is stored and released
Knowledge: Any information that the perceiver brings to a situation. See also Top-down processing.
Transduction: In the senses, the transformation of environmental energy into electrical energy. For example, the retinal receptors transduce light energy into electrical energy.
Modular organization: The organization of specific functions into specific brain structures.
lens: focuses the light on the retina; accounts for 20% of focusing
Data-based processing: Another name for bottom-up processing. Refers to processing that is based on incoming data, as opposed to top-down, or knowledge-based, processing, which is based on prior knowledge.
Action potential: Rapid increase in positive charge in a nerve fiber that travels down the fiber. Also called the nerve impulse.
Macular degeneration: A clinical condition that causes degeneration of the macula, an area of the retina that includes the fovea and a small surrounding area.
pupil: opening that allows light to pass through it
Enzyme cascade: Sequence of reactions triggered by an activated visual pigment molecule that results in transduction.
Excitatory transmitters: Neurotransmitters that cause the inside of a neuron to become more positively charged. Excitatory neurotransmitters increase the probability that an action potential will be generated and are also associated with increases in the rate of nerve firing.
Permeability: A property of a membrane that refers to the ability of molecules to pass through it. If the permeability to a molecule is high, the molecule can easily pass through the membrane.
Parietal lobe: A lobe at the top of the cortex that is the site of the cortical receiving area for touch and is the termination point of the dorsal (where or how) stream for visual processing.
Perceptual process: A sequence of steps leading from the environment to perception of a stimulus, recognition of the stimulus, and action with regard to the stimulus.
Weber fraction: The ratio of the difference threshold to the value of the standard stimulus in Weber's law.
Optic nerve: Bundle of nerve fibers that carry impulses from the retina to the lateral geniculate nucleus and other structures. Each optic nerve contains about 1 million ganglion cell fibers.
Focusing power: The degree to which a structure such as the lens or the cornea bends light. The greater the focusing power, the more the light passing through the structure is bent.
axon hillock: space between neuron and axon
Phenomenological method: Method of determining the relationship between stimuli and perception in which the observer describes what he or she perceives.
inhibitory transmitters: cause graded hyperpolarization; neuron becomes more negative; decreases the likelihood of an action potential at the axon hillock
Magnitude estimation: A psychophysical method in which the subject assigns numbers to a stimulus that are proportional to the subjective magnitude of the stimulus.
Physiological level of analysis: Analyzing perception by determining how a person's perception is related to physiological processes that are occurring within the person. This approach focuses on determining the relationship between stimuli and physiological responding and between physiological responding and perception.
Cones: Cone-shaped receptors in the retina that are primarily responsible for vision in high levels of illumination and for color vision and detail vision.
selective permeability: the membrane allows some molecules to pass more freely than others
Occipital lobe: A lobe at the back of the cortex that is the site of the cortical receiving area for vision.
Weber's law: A law stating that the ratio of the difference threshold (DL) to the value of the stimulus (DL/S) is constant. According to this relationship, doubling the value of a stimulus will cause a doubling of the difference threshold. The ratio DL/S is called the Weber fraction.
Reaction time: The time between presentation of a stimulus and an observer's or listener's response to the stimulus. Reaction time is often used in experiments as a measure of speed of processing.
Dendrites: Nerve processes on the cell body that receive stimulation from other neurons.
multipolar: local; axon is really small; sends over a short distance; not myelated
Pineal gland: Gland at the base of the brain that René Descartes identified as being the seat of the soul.
Efferent: carries info away from the structure
differences in rods and cones: shape, distribution, number, dark adaptation, spectral sensitivity, visual acuity
Recognition: The ability to place an object in a category that gives it meaning; for example, recognizing a particular red object as a tomato.
Attended stimulus: The stimulus that is being attended by a person at a given point in time.
myelin sheath: white fatty substance that insulates the axon and speeds the transmission of a signal going down the length of the axon
Outer segments: Part of the rod and cone visual receptors that contain the light-sensitive visual pigment molecules.
Wavelength: For light energy, the distance between one peak of a light wave and the next peak.
Stevens's power law: A law concerning the relationship between the physical intensity of a stimulus and the perception of the subjective magnitude of the stimulus. The law states that P = KSn, where P is perceived magnitude, K is a constant, S is the stimulus intensity, and n is an exponent.
multipolar neurons: motor
method of constant stimuli: A psychophysical method in which a number of stimuli with different intensities are presented repeatedly in a random order.
hyperpolarization: if chloride ions were added it would make it more negative; graded potential
glia cells: support the functioning of neurons; can become cancerous (neurons do not); make up 50% of the nervous system
bottom-up processing: processing based on incoming stimuli from the environment; also called data-based processing
Accommodation (focus): In vision, bringing objects located at different distances into focus by changing the shape of the lens.
sun: white light because it contains equal amounts of wavelengths
Visual transduction: Transformation of light energy into electrical energy that occurs in the rod and cone receptors in the retina.
Psychophysics: Traditionally, the term "psychophysics" refers to quantitative methods for measuring the relationship between properties of the stimulus and the subject's experience. In this book, all methods that are used to determine the relationship between stimuli and perception will be broadly referred to as pychophysical methods.
bipolar cells: receive input from rods and cones
Action: Motor activities such as moving the head or eyes and locomoting through the environment. Action is one of the major outcomes of the perceptual process.
postsynaptic neuron: receiving neurotransmitter
+30mv: peak of action potential - gates shut down for sodium at axon hillock
Absorption spectrum: A plot of the amount of light absorbed by a visual pigment versus the wavelength of light.
potassium ions: K+; positive charge; more prevalent INSIDE than outside when at rest
temporal lobe: audition
rods converging circuit: in rods in peripheral retina; 120 rods converging on a ganglion cell; good at light sensitivity
Adjustment, method of: A psychophysical method in which the experimenter or the observer adjusts the stimulus intensity in a continuous manner until the observer detects the stimulus.
psychology: study of human behavior
opsin: a large protein; component of visual pigment molecules
Inhibitory transmitters: Neurotransmitters that cause the inside of a neuron to become negatively charged. Inhibitory transmitters decrease the possibility that an action potential will be generated and are also associated with decreases in the rate of nerve firing.
Retinal: The light-sensitive part of the visual pigment molecule. Retinal is attached to the protein molecule, opsin, to form the visual pigment.
resting potential: -70 millivolts
iris: colored muscle controlling pupil size
Cell body: The part of a neuron that contains the neuron's metabolic machinery and that receives stimulation from other neurons.
Response expansion: as intensity increases, the perceived magnitude increases more QUICKLY or MORE than the intensity
Resting potential: The difference in charge between the inside and the outside of the nerve fiber when the fiber is not conducting electrical signals. Most nerve fibers have resting potentials of about -70 mV, which means the inside of the fiber is negative relative to the outside.
Monochromatic light: Light that contains only a single wavelength.
Microelectrode: A thin piece of wire that is small enough to record electrical signals from a single neuron.
Depolarization: When the inside of a neuron becomes more positive, as occurs during the initial phases of the action potential. Depolarization is often associated with the action of excitatory neurotransmitters.
Ions: Charged molecules found floating in the liquid that surrounds nerve fibers.
Rod monochromat: A person who has a retina in which the only functioning receptors are rods.
Rod: Rod-shaped receptor in the retina primarily responsible for vision at low levels of illumination. The rod system is extremely sensitive in the dark but cannot resolve fine details.
Neurotransmitter: A chemical stored in synaptic vesicles that is released in response to a nerve impulse and has an excitatory or inhibitory effect on another neuron.
Opsin: The protein part of the visual pigment molecule, to which the light-sensitive retinal molecule is attached.
Level of analysis: The idea that we can observer processes at different scales. Perception can be studied at the psychophysical and physiological levels of analysis.
Electromagnetic spectrum: Continuum of electromagnetic energy that extends from very-short-wavelength gamma rays to long-wavelength radio waves. Visible light is a narrow band within this spectrum.
Temporal lobe: A lobe on the side of the cortex that is the site of the cortical receiving area for hearing and the termination point for the ventral, or what stream for visual processing. There are a number of areas in the temporal lobe, such as the fusiform face area and the extrastriate body area, that serve functions related to perceiving and recognizing objects.
Light-adapted sensitivity: The sensitivity of the eye when in the light-adapted state. Usually taken as the starting point for the dark adaptation curve because it is the sensitivity of the eye just before the lights are turned off.
Presbyopia ("old eye"): The inability of the eye to accommodate due to the hardening of the lens and a weakening of the ciliary muscles. It occurs as people get older.
Hyperpolarization: When the inside of a neuron becomes more negative. Hyperpolarization is often associated with the action of inhibitory neurotransmitters.
Classical psychophysical methods: The methods of limits, adjustment, and constant stimuli, described by Fechner that are used for measuring thresholds.
Spontaneous activity: Nerve firing that occurs in the absence of environmental stimulation.
graded potential: with distance the depolarization dies out slowly
Visible spectrum: The band of electromagnetic energy that activates visual system and which we can, therefore, perceive. For humans, visible light has wavelengths between 400 and 700 nanometers.
Lens: The transparent focusing element of the eye through which light passes after passing through the cornea and the aqueous humor. The lens's change in shape to focus at different distances is called accommodation.
Ventricles: Cavities located at the center of the brain which were identified by Galen as the source of "spirits" that determined human health, thoughts, and emotions.
cerebral cortex layers: 6 layers; info comes IN layer 4; info goes OUT layer 5
Primary receiving areas: Areas of the cerebral cortex that first receive most of the signals initiated by a sense's receptors. For example, the occipital cortex is the site of the primary receiving area for vision and the temporal lobe is the site of the primary receiving area for hearing.
Visual pigment regeneration: Occurs after the visual pigment's two components—opsin and retinal—have become separated due to the action of light. Regeneration, which occurs in the dark, involves a rejoining of these two components to reform the visual pigment molecule. This process depends on enzymes located in the pigment epithelium.
photoreceptors: rods and cones
Inhibition: A condition that decreases the likelihood that nerve impulses will be generated.
Near point: The distance at which the lens can no longer accommodate enough to bring close objects into focus. Objects nearer than the near point can be brought into focus only by corrective lenses.
absolute threshold: the minimum stimulation needed to detect a particular stimulus 50% of the time
Synapse: A small space between the end of one neuron (the presynaptic neuron) and the cell body of another neuron (the postsynaptic neuron). See also Synaptic vesicles.
Rat-man demonstration: The demonstration in which presentation of a "ratlike" or "manlike" picture influences an observer's perception of a second picture, which can be interpreted either as a rat or as a man. This demonstration illustrates an effect of top-down processing on perception.
Psychophysical level of analysis: Analyzing perception by determining how a person's perception is related to stimuli in the environment. This approach focuses on determining the relationship between stimuli in the environment and perceptual responding.
Eye: The eyeball and its contents, which include focusing elements, the retina, and supporting structures.
3 types of cones: short, medium, long; color deficient people are missing one of the three; different because of their opsin
Pigment bleaching: The process that begins when a visual pigment molecule absorbs light. The molecule changes shape, and the color of the rod visual pigment changes from red to transparent. Visual transduction occurs at some point, early in this process.
Visual search: A procedure in which a person's task is to find a particular element in a display that contains a number of elements.
Propagated response: A response, such as a nerve impulse, that travels all the way down the nerve fiber without decreasing in amplitude.
top-down processing: processing based on the perceiver's previous knowledge; also called knowledge-based processing
Neuron: A cell in the nervous system that generates and transmits electrical impulses.
vitreous humor: jelly like substance in eye
difference threshold: The minimal detectable difference between two stimuli.
Dark adaptation curve: The function that traces the time course of the increase in visual sensitivity that occurs during dark adaptation.
Cornea: transparent/hard covering of the eye that focuses light on retina; responsible for 80% of focusing
Knowledge-based processing: Another name for top-down processing. Refers to processing that is based on knowledge, as opposed to bottom-up, or data-based, processing, which is based on incoming data.
Fovea: A small area in the human retina that contains only cone receptors. The fovea is located on the line of sight, so that when a person looks at an object, the center of its image falls on the fovea.
excitatory transmitters: cause graded depolarization; neuron becomes more positive; increases the likelihood of an action potential at the axon hillock
fissure: aka sulcus; fold that goes IN; they tend to be larger than gyrii
presynaptic neuron: releasing neurotransmitter
Cognitive influences on perception: How the knowledge, memories, and expectations that a person brings to a situation influence his or her perception.
-45mv: the threshold of excitation; thus triggering an action potential
peripheral retina: lots of rods; few cones; color and detail won't be extracted here
sodium ions: Na+; positive charge; OUTSIDE in the extracellular fluid when at rest
Staining: A technique in which neurons take up a dye that make their structure visible.
Refractory period: The time period of about 1/1,000th of a second that a nerve fiber needs to recover from conducting a nerve impulse. No new nerve impulses can be generated in the fiber until the refractory period is over.
gyrus: fold that goes OUT
Receptor site: Small area on the postsynaptic neuron that is sensitive to specific neurotransmitters.
sodium-potassium pump: protein that actively transports three sodium ions out of the cell while simultaneously drawing two potassium ions into the cell
Nerve fiber: In most sensory neurons, the long part of the neuron that transmits electrical impulses from one point to another. Also called the axon.
Perception: Conscious sensory experience.
Retina: A complex network of cells that covers the inside back of the eye. These cells include the receptors, which generate an electrical signal in response to light, as well as the horizontal, bipolar, amacrine, and ganglion cells.
Excitatory response: The response of a nerve fiber in which the firing rate increases.
Isomerization: Change in shape of the retinal part of the visual pigment molecule that occurs when the molecule absorbs a quantum of light. Isomerization triggers the enzyme cascade that results in transduction from light energy to electrical energy in the retinal receptors.
nodes of ranvier: bare spots where message gets regenerated and then shoots underneath the myelinated areas and gets regenerated thus speeding up the transmission

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