PPVK - Attention, Percp, Visual cog Flashcards
Sensation
the ability to detect a stimulus
Perception
the act of giving meaning to a detected sensation
Attention
any of the very large set of selective processes in the brain
Selective attention
when processing is restricted to a subset of the possible stimuli
PPVK (interdisciplinary field of which?
psychologists, biologists, computer scientists, medical doctors, neuroscientists…
Name scientific methods and explain them:
1.Ecological approach –observe and draw some conclussions
2.Psychophysics -use of carefully controlled laboratory stimuli →measuring behaviour
→Thresholds: finding the limits of what can be perceived
→Scaling: measuring private experience
→Signal detection theory: measuring difficult decisions
3.Neurophysiology -use of carefully controlled laboratory stimuli →measuring neural responses
→Sensory neuroscience: the biology of cognitive processes
→Neuroimaging: an image of the mind
4.Computational models: using math and computation to understand cognition
Gustav Fechner (explain why he was important)
- invented “psychophysics”
- the true founder of experimental psychology
- Fechner –from a degree in medicine, to biological science to physics and mathematics
-Damaged his eyes by staring at the sun while performing vision experiments
Psychophysics
the science of defining quantitative relationships between physical and psychological (subjective) events
Absolute threshold
minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time
Just noticeable difference (JND; difference threshold)
the smallest detectable difference between two stimuli, or the minimum change in a stimulus that can be correctly judged as different from a reference stimulus
Absolute treshold (vision, hearing, vestibular, taste,smell, touch)
Stars at night, or a candle flame 30 miles away on a dark, clear night
A ticking watch 20 feet away, with no other noises
A tilt of less than half a minute on a clock face
A teaspoon of sugar in 7.5 liters of water
A drop of perfume in 3 rooms
The wing of a fly falling on your cheek from a height of 3 inches
Psychophysics and Thresholds
Weber’s law
the JND is a constant fraction of the comparison stimulus
larger stimulus values have larger JNDs and smaller stimulus values have smaller JNDs
Who extended Weber’s law?
Fechner
Fechner’s law
*the magnitude of subjective sensation increases proportionally to the logarithm of the stimulus intensity
*An attempt to equate mind and matter
What are psychophysical methods?
*Method of constant stimuli
→ many stimuli, ranging from rarely to almost always perceivable, are presented one at a time
*Method of limits
→ the magnitude of a single stimulus or the difference between two stimuli is varied incrementally until the participant responds differently
*Method of adjustment
→ similar to the method of limits, but the participant controls the stimulus directly
Name scaling methods
Magnitude estimation, Cross-modality matching
Magnitude estimation
→the participant assigns values according to perceived magnitudes of the stimuli
→the method of adjustment → magnitude estimation on a finer scale
→magnitude estimates are well described by Stevens’ power law:
S = aIb
(S) is related to stimulus intensity (I) by an exponent (b)
Cross-modality matching
→matching the intensity of a sensation in one sensory modality with the intensity of a sensation in another
→bitter propylthiouracilPROP
SDT
A psychophysical theory - response of an observer to the presentation of a signal in the presence of noise
SDT makes a distinction between:
*observers’ ability to perceive a signal
*observers’ willingness to report a signal
Sensitivity
observers’ ability to perceive a signal
Criterion
observers’ willingness to report a signal
Cranial nerves
12 pairs of nerves (one for each side of the body) that originate in the brain stem and reach sense organs and muscles
Name cranial nerves for sensory information
*Olfactory (I)
*Optic (II)
*Auditory (VIII)
Muscles that move the eyes (cranial nerves)
*Oculomotor (III)
*Trochlear (IV) nerves
*Abducens (VI) nerves
Parts of neuron?
dendrites, soma, axon, myelin sheath, nodes of ranvier, axon(synaptic) terminals, schwann cells
Dendrites
Branch-like structures that receive signals from other neurons and transmit them to the cell body.
Cell body (soma)
The main part of the neuron containing the nucleus, which processes incoming signals.
Axon
A long, tube-like structure that carries electrical impulses away from the cell body toward other neurons or muscles.
Myelin Sheath
A fatty layer that covers the axon, insulating it and speeding up signal transmission.
Nodes of ranvier
Gaps in the myelin sheath that help speed up the transmission of nerve impulses.
Axon terminals
The ends of the axon that release neurotransmitters to communicate with other neurons or target cells.
Schwann cells
support neurons, especially in forming the myelin sheath around axons
Which nerves are dedicated to specific sensory and motor tasks?
Cranial nerves
Polysensory brain areas
→ information from several senses is combined
→ sensory integration (multisensory integration): the process of combining different sensory signals
Electroencephalography (EEG)
A technique that 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)
→similar to EEG
→measures changes in magnetic activity across populations of many neurons in the brain
→has the same high temporal resolution as EEG, but better spatial resolution
Computerized tomography (CT)
→an imaging technology that uses X-rays
→creates images of slices through volumes of material (e.g., the human body)
Magnetic resonance imaging (MRI)
→an imaging technology that uses the responses of atoms to strong magnetic fields
→forms images of structures like the brain
Functional magnetic resonance imaging (fMRI)
→variant of MRI
→measures localized patterns of brain activity
→activated neurons provoke increased blood flow, which can be quantified by measuring changes of oxygenated and deoxygenated blood to strong magnetic fields
-> BOLD signal
blood oxygen level-dependent (BOLD) signal
→the ratio of oxygenated to deoxygenated hemoglobin
→permits the localization of brain neurons that are most involved in a task
Positron emission tomography (PET)
→measures the metabolism of brain cells using safe radioactive isotopes
→allows us to define locations in the brain where neurons are especially active
What comupational models aim to simulate?
the steps in psychological and/or neural processes in a computer using mathematical language and equations.
Efficient coding models
models that discover structure in sensory input to efficiently encode the world
Bayesian models
models that make predictions (predictive coding) based on prior knowledge about the world
Artificial Neural Networks
models that simulate biological neurons with layers of input units massively interconnected with output units that can excite or inhibit each other
Deep neural nets (DNNs)
artificial neural networks with a very large number of layers of nodes with millions of connections between the input and output layers.
