Chapter 1- Introduction Flashcards
Sensation
The ability to detect a stimulus and, perhaps, to turn that detection into a private experience.
Perception
The act of giving meaning to a detected sensation.
What are the six methods used to measure how sensitive our senses are?
Method 1: Thresholds
Method 2: Scaling- Measuring Private Experience
Method 3: Signal Detection Theory- Measuring Difficult Decisions
Method 4: Sensory Neuroscience
Method 5: Neuroimaging- An Image of the Mind
Method 6: Computational Models
Qualia
In reference to philosophy, private conscious experiences of sensation or perception.
Who is Gustav Fechner?
Thought to be the true founder of experimental psychology, he is best known for his pioneering work relating changes in the physical world to changes in our psychological experiences, thus inventing the field of psychophysics.
Dualism
The idea that the mind has an existence separate from the material world of the body.
Materialism
The idea that the only thing that exists is matter, and that all things, including the mind and consciousness, are the results of interaction between bits of matter.
Panpsychism
The idea that the mind exists as a property of all matter- that is, that all matter has consciousness.
Psychophysics
The science of defining quantitative relationships between physical and psychological (subjective) events.
Who is Ernst Weber?
He discovered the smallest detectable change in stimulus, such as the weight of an object, is a constant proportion of the stimulus level. This relationship later became known as Weber’s Law.
Two-Point Touch Threshold
The minimum distance at which two stimuli (e.g., two simultaneous touches) are just perceptible as separate.
Just Noticeable Difference (JND)
The smallest detectable difference between two stimuli, or the minimum change in stimulus that enables it to be correctly judged as different form a reference stimulus.
Difference Threshold
Another term for the smallest change in stimulus that can be detected (In reference to the JND).
Weber Fractions
The constant of proportionality in Weber’s Law.
Weber’s Law
The principle describing the relationship between stimulus and resulting sensation that says the just noticeable difference (JND) is a constant fraction of the comparison stimulus.
Fechner’s Law
A principle describing the relationship between stimulus and resulting sensation that says the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity.
Units of physical entities versus measures of people’s perception.
Physical entities refer to things such as light or sound. Meanwhile people’s perception refers to things such as “brightness” or “loudness”.
Frequency versus Pitch
Frequency is the measure of the rate of fluctuations in the physical sound pressure, while the pitch of a musical note describes a psychophysical response to that physical phenomenon.
Absolute Threshold
The minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time.
Method of Constant Stimuli
A psychophysical method in which many stimuli, ranging from rarely to almost always perceivable (or rarely to almost always perceivably different from a reference stimulus), are presented one at a time. Participants respond to each presentation: “yes/no,” “same/different,” and so on.
Method of Limits
A psychophysical method in which the particular dimension of a stimulus, or the difference between two stimuli, is varied incrementally until the participant responds differently.
Method of Adjustment
A method of limits in which the participant controls the change in the stimulus.
Magnitude Estimation
A psychophysical method in which the participant assigns values according to perceived magnitudes in the stimuli.
Steven’s Power Law
A principle describing the relationship between stimulus and resulting sensation that says the magnitude of subjective sensation is proportional to the stimulus magnitude raised to an exponent.
Compare Weber’s Fechner’s and Steven’s Laws
1) Weber’s law involves clear objective measurement. We know how much we varied the stimulus, and either the observers can tell the stimulus changed or they cannot.
2) Fechner’s law begins with the same sort of objective measurements as Weber’s, but the law is actually a calculation based on some assumptions about how sensation works. In particular, Fechner’s law assumes that al JNDs are perceptually equivalent. In fact, this assumption turns out sometimes to be incorrect and leads to instances where the “law” is violated…
3) Stevens’s power law describes rating data quite, well, but notice that rating data are qualitatively different form the data that support Weber’s law. We can record the observer’s ratings and we can check whether those ratings are reasonable and consistent, but there is no way to know whether they are objectively right or wrong.
Cross-Modality Matching
The ability to match the intensities of sensations that come from different sensory modalities. This ability allows insight into sensory differences. For example, a listener might adjust the brightness of a light until it matches the loudness of a tone.
Signal Detection Theory
A psychophysical theory that quantifies the response of an observer to the presentation of a signal in the presence of noise. Measures obtained form a series of presentations are sensitivity (d’) and criterion of the observer.
Criterion
In reference to signal detection theory, an internal threshold that is set by the observer. If the internal response is above criterion, the observer gives one response (e.g., “yes, I hear that”). Below criterion, the observer gives another response (e.g., no, I hear nothing.)
What are the four positive outcomes?
1) Correct rejection or true negative
2) Hit or true positive
3) False alarm or false positive
4) Miss or false negative.
Sensitivity
In reference to signal detection theory, a measure that defines the ease with which an observer can tell the difference between the presence and absence of a stimulus or the difference between Stimulus 1 and Stimulus 2.
Receiver Operating Characteristic (ROC) Curve
In reference to studies of signal detection, the graphical plot of the hit rate as a function of the false-alarm rate. If these are the same, points fall on the diagonal, indicating that the observer cannot tell the difference between the presence and absence of the signal. As the observer’s sensitivity increases, the curve bows upward toward the upper left corner. That point represents a perfect ability to distinguish signal from noise (100% hits, 0% false alarms).
Doctrine of Specific Nerve Energies
A doctrine formulated by Johannes Muller, stating that the nature of a sensation depends on which sensory fibers are stimulated, rather than how they are stimulated.
Cranial Nerves
Twelve pairs of nerves (one for each side of the body) that originate in the brain stem and reach sense organs and muscles through openings in the skull.
Olfactory (I) Nerves
The first pair of cranial nerves. The axons of the olfactory sensory neurons bundle together after passing through the cribriform plate to form the olfactory nerve, which conducts impulses from the olfactory epithelia in the nose to the olfactory bulb.
Optic (II) Nerves
The second pair of cranial nerves, which arise from the retina and carry visual information to the thalamus and other parts of the brain.
Oculomotor (III) Nerves
The third pair of cranial nerves, which innervate all the extrinsic muscles of the eye except the lateral rectus and the superior oblique muscles, and which innervate the elevator muscles of the upper eyelid, the ciliary muscle, and the sphincter muscle of the pupil.
Vestibulocochlear (VIII) Nerves
The eighth pair of cranial nerves, which connect the inner ear with the brain, transmitting impulses concerned with hearing and spatial orientation. The vestibulocochlear nerve is composed of the cochlear nerve branch and the vestibular nerve branch.
Trochlear (IV) Nerves
The fourth pair of cranial nerves, which innervate the superior oblique muscles of the eyeballs.
Abducens (VI) Nerves
The sixth pair of cranial nerves, which innervate the lateral rectus muscle of the eyeballs.
Warmth and Cold Fibers
These are two specialized types of nerve cells which respond to increases and decreases in temperature on the skin.
Menthol
Imparts a minty flavor in cough drops and stimulates cold fibers so the skin feels cooler without getting physically colder.
Capsaicin
A chemical that occurs naturally in chili peppers. It causes warmth fibers to fire, creating a sense of increasing heat even though the temperature has not changed.
Polysensory
Referring to blending multiple sensory systems.
Sensory Integration or Multi-Sensory Integration
The process of combining different sensory signals. The senses typically work together to learn about the world and to guide behavior. This is not the same as the mathematical process of integration learned in calculus (e.g., the integral of acceleration is velocity).
Synapse
The junction between neurons that permits information transfer.
Neurotransmitters
A chemical substance used in neuronal communication at synapses.
Explain how neural firing works:
A neuron “fires” when a stimulus makes the voltage across a piece of the cell membrane a bit more positive than its negative “resting potential”. This is called depolarization. Depolarization permits sodium ions (Na+) to rush into the cell, thus increasing the voltage and generating an action potential. Very quickly afterward, potassium ion (K+) flow out of the cell, bringing the voltage back to the resting voltage. An action potential is analogous to a wave, sweeping across the ocean or around a football stadium. Here, the action potential sweeps along the length of the axon until it reaches the axon terminal.
Neuroimaging
A set of method that generate images of the structure and/or function of the brain. In many cases, these methods allow us to examine the brain in living, behaving humans.
Electroencephalography (EEG)
A technique that, using many electrodes on the scalp, measures electrical activity from populations of many neurons in the brain.
Event-Related Potential (ERP)
A measure of electrical activity from a subpopulation of neurons in response to particular stimuli that requires averaging many EEG recordings.
Magnetoencephalography (MEG)
A technique, similar to electroencephalography, that measures changes in magnetic activity across populations of many neurons in the brain.
Magnetic Resonance Imaging (MRI)
An imaging technique that uses the responses of atoms to strong magnetic fields to form images of structures like the brain. The method can be adapted to measure activity in the brain, as well.
fMRI
A variant of magnetic resonance imaging that makes it possible to measure localized patterns of activity in the brain. Activated neurons provoke increased blood flow, which can be quantified by measuring changes in the response of oxygenated and deoxygenated blood to strong magnetic fields.
Blood Oxygen Level-Dependent (BOLD) Signal
The ratio of oxygenated to deoxygenated hemoglobin that permits the localization of brain neurons that are most involved in a task.
Positron Emission Tomography (PET)
An imaging technology that enables us to define location in the brain where neurons are especially active by measuring the metabolism of brain cells using safe radioactive isotopes.
Mathematical Model
The use of mathematical language and equations to describe psychological and/or neural processes.
Computational Model
The use of mathematical language and equations to describe steps in psychological and/or neural processes (often implemented on a computer).
Efficient Coding Models
Theoretical and/or computational models that explain neural processing by assuming that sensory systems become tuned to predictability in natural environments in ways that economically encode predictable sensory inputs while highlighting inputs that are less predictable.
Bayesian Models
Theoretical and/or computational models that employ Bayesian statistical methods to generate an internal model of the source of sensory inputs based upon prior experience.
Predictive Coding
The use of Bayesian models to predict future inputs. If predictions do not match inputs (prediction error), the model is adjusted to improve future predictions.
Artificial Neural Networks (Connectionist Models)
Computational methods that consist of networks of nodes with weighted connections between them. Connection weights increase and decrease following experience in ways that resemble organization of biological neural networks.
“Supervised” versus “Unsupervised”
If a model is given feedback when it is right or wrong, it is a “supervised” model; models without this feedback are “unsupervised”.
Deep Neural Networks (DNNs)
Artificial neural networks that have a very large number of layers of nodes with millions of connections.
