Sensation & Perception (part 1) Flashcards
The first 5 weeks of the course, so everything for exam 1!
What five methods to study sensation and perception does the book mention?
- Thresholds
- Scaling
- Signal Detection Theory
- Sensory neuroscience
- Neuroimaging
Psychophysics
A method to formally describe the relationship between sensation and the energy or matter that gives rise to that sensation.
Who named the psychophysics method?
Gustav Fechner
JND (abbreviation)
just noticeable difference
Panpsychism
The idea that the mind exists as a property of all matter, that all matter has consciousness.
Perception
Giving meaning or purpose to detected sensations.
Who are seen as the founders of experimental psychology?
Gustav Fechner (1801-1887) and Wilhelm Wundt (1832-1920).
Who made sense of the way in which JND changes?
Ernst Weber (1795-1878)
What are the Weber fractions concerned with?
The systematic way in which the JND changes: a constant ratio between change in stimulus and standard stimulus, which describes the threshold of the detectable change.
Weber’s law (formula)
[delta].I = K.I
Weber’s law (intuitive)
The size of the detectable difference is equal to a constant proportion of the level of stimulus.
Fechner’s law (formula)
S = k * log (R)
Fechner’s law (intuitive)
The psychological sensation is equal to a constant k times the logarithm of the physical stimulus level, so our experience of intensity increases less than the actual stimulus increases.
Absolute threshold
The minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time.
What three ways os studying thresholds are discussed in the book?
- Method of constant stimuli
- Method of limits
- Method of adjustment
Method of constant stimuli
Many stimuli with different intensities are presented one at a time, to find the smallest intensity that can be detected.
Method of limits
Stimuli with different intensities. In order of increasing or decreasing intensity until first detected or not detected anymore. Average is taken as threshold.
Method of adjustment.
Method of limits where the participant adjusts the stimuli intensity herself.
Magnitude estimation
A task in which participants need to rank a number of sensations based on perceived intensity.
Steven’s power law (formula)
S = a * (I^b)
Steven’s power law (intuitive)
The magnitude of subjective sensation S is related to the stimulus intensity I by exponent b. We use constant a to correct for the units used.
Cross-modality matching
Participants have to adjust a stimulus of one kind to match the intensity of another kind of stimulus.
Qualia
The experiences when you see/hear something, the qualitative experience.
How can we deal with a non-absolute threshold?
Signal Detection Theory
What is the simplest kind of sound?
A sinus wave.
What do we call the time taken for a wavelength in sound?
a period
What do we call the height of a wave in sound?
the amplitude
What is the phase of a wave in sound?
The position relative to a fixed marker, measured in degress.
How many degrees are there across one period in sound?
360
Fourier analysis
The process of breaking down a complex sound into individual sine wave components. (or images into spatial frequencies)
What are units of spatial frequency?
cycles per degree of visual angle
Doctrine of specific nerve energies
We are only aware of the activity in our nerves, not directly of the world itself. It isn’t important how nerves are stimulated, but what nerves are stimulated.
What cranial nerves are dedicated to sensory information?
- Olfactory nerve
- Optic nerve
- Vestibulocochlear nerve
What cranial nerves are dedicated to muscles that move the eyes?
- Oculomotor nerve
- Trochlear nerve
- Abducens
Vitalism
The idea that there is a force in life that is distinct from physical entities.
Synapse
The tiny gap between the axe of one neuron and the dendrite of the next. Permits information transfer.
What happens to the speed of neural transmission at the synapses?
It decreases.
EEG
electroencepalography
ERP
event-related potential
MEG
magnetoencephalography
CT
computed tomography
MRI
magnetic resonance imaging
How does EEG work?
It measures electrical activity with electrodes on the scalp.
What are the results of an EEG?
Can roughly localize populations of neurons, but not able to pinpoint area of neural activity. Very good temporal accuracy.
What is an ERP?
A measure of electrical activity from a subpopulation of neurons in response to particular stimuli, the average waveform that results from many EEG recordings.
What results does an MEG give?
Tiny magnetic field changes, maintains timing of neuron populations and has good image of where in the brain neurons are most active.
What results does a CT give?
A 3D picture of the head.
BOLD
blood oxygen level-dependent
What results does an MRI give?
The BOLD signal is measured, slow and noisy and expensive but still good.
PET
positron emission tomography
What is PET?
An imaging technique where radioactive material goes into the bloodstream and a camera detects gamma rays.
What is the most common tracer in PET?
oxygen-15 with a half-life of +-2 minutes.
Electromagnetic radiation
Energy produced by vibrations of electrically charged material.
Photons
Tiny particles that each consist of one quantum of energy, demonstrating both particle and wave properties.
How do we treat light in the book?
As being made up of waves when it moves around the world, and being made up of photons when it is absorbed.
What wavelengths of the spectrum of electromagnetic radiation is light?
Between 400 and 700 nm wavelength.
Hue
The perceptual attribute of colors.
What portions of the electromagnetic radiation spectrium have a smaller wavelength than light?
Gamma rays, X-rays and Ultraviolet.
What portions of the electromagnetic radiation spectrum have a larger wavelength than light?
Infrared, heat, microwaves, FM radio and television.
What is the speed of light?
About 186.000 miles per second = 299.792 kilometer per seconde.
What wavelength is scattered more strongly?
Short-wavelength.
Refraction
When light rays are bent, for example by windows.
Where does the light first get to in the eye?
The cornea.
What does the aqueous humor do?
Supplies oxygen and nutrients to the cornea and cleans the cornea and the lens.
Pupil
A hole in the iris, where the light passes through.
What controls the size of the pupil?
The iris.
What happens when the pupil is large?
The depth of focus is smaller and image quality poor. Used for low light.
Vitreous chamber
Located between the lens and the retina, filled with the vitreous humor.
Vitreous humor
The gel-like substance in the vitreous chamber, refracts the light for the fourth time.
Transduction
The process in the retina where the light energy is turned into electrical neural signals.
What four components of the eye refracts the incoming light?
- the cornea
- the aqueous humor
- the lens
- the vitreous humor
What do the refractive powers of the cornea, aqueous humor, lens and vitreous humor need to be matched to?
The length of the eyeball.
What component of the eye has the most refractive power?
The cornea.
What three components of the eye have a fixed refractive power?
- the cornea
- the aqueous humor
- the vitreous humor
Accomodation
The process of the lens altering the refractive power of the eye by changing shape. Lens gets fatter when gaze directed to nearer objects.
What muscle contracts in accomodation in the eye?
The ciliary muscle.
What happens when the ciliary muscle is relaxed?
The lens is flat and the zonules are stretched. For looking at distant objects.
Lens power (formula)
P = 1/f
with f = focal distance in meters.
D
diopters, a unit to measure accomodation
How does our accomodation change when we get older?
We lose about 1D every 5 years from 8 y/o to 30 y/o.
Presbyopia
Old sight, when old people can’t see at 2.5D anymore. Happens to almost everyone since lens loses elasticity, they lose accomodation.
Why is the lens transparent?
Because it consists of packed together crystallins (proteins).
Cataracts
Opacities of the lens that happen when the regularity of crystallins is disturbed.
Emmetropia
When the refractive power of the eye is perfectly matched to the length of the eyeball.
Refractive errors
When the eyeball is too long or too short relative to the refractive power of the four components, so the image of the world is not clearly focused on the retina.
Myopia
Nearsightedness: When the image is focused in front of the retina, so blur far away.
Hyperopia
Farsightedness, when the eyeball is too short and the images is focused behind the retina. Near objects seen unclearly.
Foveal vision
The central 1.5-2 degrees of the visual field.
Peripheral vision
The visual field outside of the foveal vision.
How are photoreceptor types distributed over the visual field?
Mostly cones in the fovea and mostly rods in the periphery.
How are bipolar cells distributed over the visual field?
Midget bipolar cells in the fovea and diffuse bipolar cells in the periphery.
How is convergence distributed over the visual field?
Low convergence in the fovea and high convergence in the periphery.
How is receptive field size distributed over the visual field?
Small receptive field size in the fovea and large receptive field size in the periphery.
How is acuity distributed over the visual field?
High acuity in the fovea and low acuity in the periphery.
How is light sensitivity distributed over the visual field?
Low light sensitivity in the fovea and high light sensitivity in the periphery.
Acuity
Detail
Astigmatism
When the cornea is not spherical, but more circle-like: vertical lines in front of retina and horizontal lines behind retina or vice versa.
How can astigmatism be corrected?
By lenses that have two focal points.
LASIK
laser-assisted in situ keratomileusis
What is LASIK?
An eye surgery where the cornea is reshaped to correct refractive power.
Fundus
The back part of the eye.
Optic disc
A white circle on the fundus where the arteries and veins enter the eyes and the axons of ganglion cells leave the eye via the optic nerve. Has no photoreceptors, so it’s blind.
Fovea
A spot near the center of the macula containing the highest concentration of cones and no rods. Serves as the point of fixation.
Pigment epithelium
A layer of darker cells in the retina, the layer furthest back.
What does the light need to pass through before making contact with the photoreceptors?
The ganglion, horizontal and amacrine cells.
Why are the photoreceptors in their specific location?
The need to be next to the pigment epithelium for nutrition and recycling, as well as next to the other neurons in order to pass along their signals.
How many rods and cones does a human have per eye?
About 90 milion rods and 4-5 million cones.
Retinal eccentricity
Distance from the fovea.
Duplex retina
A retina that consists of both rods and cones.
What happens if we look directly at an object whose image is smaller than one degree?
The image will land on a region of the retina that has only cones.
For what vision stuff do we use the fovea?
To identify objects, read and inspect fine detail.
For what vision stuff do we use the periphery?
When detecting and localizing stimuli that we aren’t looking at directly.
What photoreceptor type picks up on color?
The cones
Photic sneeze reflex
Sneezing in response to being exposed to bright lights.
In what four ways does the visual system adjust to changes in illumination?
- Pupil size
- Photopigment regeneration
- The duplex retina
- Neural circuitry
How does the pupil size adjust to changes in illumination?
The diameter can vary by a factor of about 4. Size determines the amount of light that enters the eye. Takes a few seconds to change, but many minutes in dark adaptation.
How does photopigment regeneration adjust to changes in illumination?
With low light, there is many photopigment and rods & cones respond to as many photons as possible. Photopigment is bleached when photon is detected and needs to be regenerated. With a lot of light: many photons, photopigment molecules cannot be regenerated fast enough.
How does the duplex retina adjust with changes in illumination?
Rods are used when light is low and cones take over when there is too much light for the rods to function well.
How does neural circuitry adjust with change in illumination?
Ganglion cells are most sensitive to light differences in their center & surround of receptive fields, not so affected by average intensity of light. Encode patterns of light & dark areas in retinal image.
Receptive field
Region on the retina where visual stimuli influence neuron’s firing rate.
AMD
age-related macular degeneration
What happens in age-related macular degeneration (AMD)?
The macula is affected and gradually destroys sharp central vision.
RP
retinitis pigmentosa
What happens in retinitis pigmentosa?
There’s a progressive degeneration of the retina that affects night vision and peripheral vision.
What are the 5 classes of neurons in the retina?
- Photoreceptors
- Horizontal cells
- Bipolar cells
- Amacrine cells
- Ganglion cells
Photoreceptors
Neurons that produce chemical changes that start a neural events chain. Sends signals by synaptic terminals.
What do photoreceptors consist of?
An outer segment, inner segment and synaptic terminal.
What does the inner segment in a photoreceptor do?
It makes visual pigments.
What does the outer segment in a photoreceptor do?
It stores the visual pigments that the inner segment made.
What does a visual pigment molecule consist of?
Protein (opsin) and cromophore.
Cromophore
Captures light signals, retinal.
Rhodopsin
A visual pigment in rods
Melanopsin
A photopigment that is sensitive to ambient light. Specifically found in a photosensitive ganglion cell in the retina.
Lateral inhibition
Antagonistic neural interaction between adjacent regions of the retina. Enables signals to be based on differences in activation between nearby photoreceptors.
What is the role of bipolar cells?
Determine info that is passed from phootreceptors to ganglion cells. Are small, have a specific amount of neurotransmitter release and all the same rate of response.
Describe the response pattern of diffuse bipolar cells
Respond to a single point of bright light at the same rate as to several sports of dim light.
Midget bipolar cells
what do they do + where?
Pass info from single cones to single ganglion cells and exist only in the fovea.
What is the location of the amacrine cells?
Part of the lateral pathway, they’re in the inner layers of the retina.
What is the role of amacrine cells?
Receive inputs from bipolar cells and other amacrine cells and send signals to bipolar, amacrine,and retinal ganglion cells.
Serve as a switch between rod and cone system.
Where are the ganglion cells
The final layer of the retina, can be P or M ganglion cells.
Where from do P ganglion cells receive + what do they feed?
Receive from the bipolar cells and feed the parvocellullar layer of the LGN
M ganglion cells
Receive from the diffuse bipolar cells and feed the magnocellular layer of the LGN.
LGN
lateral geniculate nucleus
Photoactivation
Bleaching: the process where a photon is absorbed by a molecule of rhodopsin in the outer segment of a rod and transfers its energy to the chromophore portion of the visual pigment molecule.
Hyperpolarization
A change in membrane potential such that the inner membrane surface becomes more negative than the outer membrane surface.
S-cones
short-wavelength sensitive cones
What do we mean with ‘the foveal centre is dichromatic’?
It has only two color-sensitive cone types.
L-cones
long wavelength sensitive cones
M-cones
medium-wavelength sensitive cones
Photopic
Light intensities that are bright enough to stimulate the cone receptors and saturate the rod receptors (drive them to max response)
scotopic
Light intensities that are bright enough to stimulate the rod receptors but too dim to stimulate the cone receptors.
What type of cones misses from the center of the fovea?
S-cones
What cells form a lateral pathway in the retina?
Horizontal and amacrine cells
What cells form a vertical pathway in the retina?
Photoreceptors, bipolar cells and ganglion cells.
ON-center bipolar cell
Increases firing rate when light in center of RF, decreasing firing rate when light in surround. Depolarizes in response to increase in light.
OFF-center bipolar cell
Hyperpolarizes in response to increase in light. Responds to light in the surround, not in the center.
RGC
retinal ganglion cell
RF
receptive field
When does a ganglion cell fire the fastest?
When the spot of light is the same size as the excitatory centre. (just the right size, less when larger or smaller).
Center-surround antagonism
lateral inhibition
What is the effect of a high degree of convergence in the retinal periphery?
High sensitivity to light, but poor acuity.
What is the effect of the low degree of convergence in the fovea?
High acuity, but poor sensitivity to light.
Why are images seen more clearly when they fall on the fovea?
Only there there are one-to-one pathways between cones and ganglions.
What are our senses?
- Vision
- Hearing
- Taste
- Smell
- Touch
What is the fancier word for the hearing sense?
Audition.
What is the fancier word for the taste sense?
Gustation
What is the fancier word for the smell sense?
Olfaction
What is the fancier word for the touch sense?
Somatosensation
What is the sixth sense according to Harvey?
Balance
What is the fancier word for balance?
Vestibular
Which of the senses is our primary sense?
Vision (/sight)
Sensation
The translation of the external physical environment into a pattern of neural activity (by a sensory organ).
What is the method in perceptual threshold detection called where you change the difficulty of the next trial depending on the answer on the previous trial?
The adaptive method.
What are the three types of brain activity discussed in lecture 1?
- Spiking activity
- Synaptic activity
- Metabolic activity
Spike activity
Brain activity: spikes are action potentials of individual neuron. Can be measured directly from the neuron (ethical issues).
What is + how do you measure synaptic activity
Synaptic potentials, can be measured with scans by putting a detector in between two cells and measure results of them firing.
What is metabolic activity?
Oxygen and glucose consumption.
Describe the cycle of interaction between excitatory and inhibitory neurons:
When excitaroy pool becomes active, it activates the inhibitory pool. The inhibitory pool becomes activated then and inhibits the excitatory pool so that its activity goes down. The excitatory pool stops exciting the inhibitory pool, and thus the injibitory pool stops inhibiting the excitatory pool which then gives rise to activity in the excitatory pool, and back to the start.
LFP
Local field potential.
What is the influence of the LFP on perception?
When the local field potential is high, you’re more likely to perceive than when it is low.
How does the measurement of fMRI work?
The human body is mainly water. All the atoms point the same way when in a permanent static magnetic field. But if pushed in another field in a different direction, and that second field is removed, the atoms bounce back in their position and release activity. Now you can measure water density.
Where does the translation from photons to electrical signals happen?
In the photoreceptors.
How are photons translated to neural signals?
Cross-membrane proteins in the photoreceptors change structure if they catch a photon and then their membrane opens. Potassium can come out then.
What type of photoreceptor do we see colors with?
Cones
Rhodopsin
The protein in a rod photoreceptor.
Horizontal cell (role in chain)
Get input from photoreceptors and output inhibition.
Where are they + what do they do? Postreceptoral layers of the retina
In the eyeball, translate the raw light array captured by the photoreceptors into the patterns of spots surrounded by darkness detected by ganglion cells.
What do ganglion cells in the retina respond well to?
Spots of light
What do neurons in the cerebral cortex respond well to?
Lines, edges and stripes.
Contrast
Difference in illuminaton.
Wat is a cycle when talking about grating vision?
One repetition of a black and white stripe.
Visual angle
The angle that would be formed by lines going from top/bottom or left/right of a cycle on the page, passing through the center of the lens and ending on the retina.
How many degrees is one centimeter?
1
How many arc minutes is one centimeter/one degree?
60
Why is visual acuity poorer in the periphery compared to the fovea?
Rods and cones are less tightly packed together and less receptors converge on each ganglion cell.
Horizontal and vertical assymetry
The visual acuity in the peripheral vision is not uniform, it degrades more rapidly along the vertical midline of the visual field.
Vertical meridian assymetry
We have a better acuity a fixed distance below the midline of the visual field than above.
What type of vision is slower: central or peripheral?
Central vision is slower: foveal cones have longer axons which transmit slow signals better.
What does 20/15 vision mean?
THa you’re worse than average, because you need to stand at 15m instead of 20m to read the letters.
Amblyopia
A developmental disorder with reduced spatial vision in a healthy eye, even with proper correction for refractive error. = Lazy eye
List the different forms of acuity:
- Minimum visible
- Minimum resolvable
- Minimum recognizeable
- Minimum discriminable
Minimum visible acuity
The smallest object that one can detect. Limited by our ability to discriminate intensity relative to background.
Minimum resolvable acuity
THe smallest angular separation between neighboring objects that one can resolve. Limited by spacing of photoreceptors in retina (foveal vision).
Minimum recognizable acuity
The angular size of the smallest feature that one can resolve.
Minimum discriminable acuity
The angular size of the smallest change in a feature that one can discriminate.
Vernier acuity
The smallest misalignment one can reliably discern when looking at two lines that are aligned.
Spatial frequency
The number of times a pattern repeats in a given unit of space.
CSF
contrast sensitivity function.
Michelson definition of the CSF
C = (Lmax - Lmin) / (Lmax + Lmin)
with L = luminance
Geniculate
‘bent’
What spatial frequency does an ON-center ganglion cell respond well to?
Medium spatial frequency
Why does an ON-center cell responds well to medium frequency?
With a low SF, the bright bar of gratings lands in the inhibitory surround and with a high SF, both dark and bright bars fall within the receptive field center.
How many layers does the LGN consist of?
6
What are the bottom two layers of the LGN called?
Magnocellular layers
Why are the bottom two layers of the LGN called ‘magnocellular layers’?
Because there are larger neurons there than in the top four layers.
Magnocellular layers
Receive input from M ganglion cells in the retina. Responds to large, fast-moving objects.
What are the top four layers of the LGN called?
Parvocellular layers
Parvocellular layers
The top four layers in the LGN, have smaller neurons than the magnocellular layers. Receive input from P ganglion cells. Responsible for processing details of stationary targets.
What do the layers in-between the layers in the LGN consist of?
Koniocellullar cells
Contralateral
Left eye
What layers of the LGN receive contralateral input?
1, 4 and 6
Ipsilateral
Right eye
What layers of the LGN receive ipsilateral input?
Layers 2, 3 and 5.
From what eye does the right LGN receive input?
Left eye
Topographical mapping
The orderly mapping of the world in the lateral geniculate nucleus and the visual cortex.
What is written about the connections between the LGN and the visual cortex? (direction, ratio)
There are more feedback connections from the visual cortex to the LGN than feed-forward from LGN to visual cortex.
What part of the brain is inhibited while sleeping?
the thalamus (LGN is part of thalamus, so no vision while sleeping)
Inion
A bump at the back of your head, below which is the primary visual cortex.
V1
Primary visual cortex
Area 17
Prmary visual cortex
How is the striate cortex built up?
Six layers, some having sublayers.
What layer of the striate cortex does the LGN project to?
Mostly to layer 4.
Where do the magnocellular axons go in the striate cortex?
The upper part of layer 4C, called 4Calpha
What part of the striate cortex do the parvocellular axons connect to?
The lower part of layer 4C, called 4Cbeta
Name two important features of the visual cortex:
- Topograhpy
- Magnification
Cerebral cortex
Primary visual cortex
Cortical magnification
The process that objects on the fovea get much more processing space in the cortex than objects in the periphery.
->Cortical representation of fovea is magnified compared to that of peripheral vision.
Visual crowding
A phenomenon in the periphery when objects are not recognized as well because they appear combined with surroundings.
Ocular dominance
The property of striate receptive fields that they have a preference for a stimulus in one eye versus the other eye.
Simple cell
The ‘line detector’. An edge detector in V1 that has clear ON and OFF regions, is orientation selective and gets input from LGN cells.
Edge detector
The three types of cells in V1. Have large receptive fields and are the basis of simple object recognition.
Stripe detector
The simple cell. Excited when a line of light with a particular width is surrounded by darkness.
Complex cells
The ‘motion detector’. No clear ON and OFF regions. Respond best to a moving edge with a particular orientation and direction. Get input from simple cells.
End stopping
A property of some cells in the striate cortex. Happens in hypercomplex cells: response rate increases when filling up RF, but decreases as bar extends beyond RF.
Perpendicular
Loodrecht op
Hypercolumn
A column of 2 sets of columns: each set has one left dominant & one right dominant column that both have every possible orientation. Responsible for all processing of a small part of the visual field.
CO
Cytochrome oxidase
Cytochrome oxidase blobs
Arranged in a regular array, implicated in processing color and the interblob regions in processing motion and spatial structure.
Adaptation
Method where neural firing is measured for a certain stimulus, the stimulus adapted and change in neural firing rate measured. Cells might be fatigues after first representation, so cells next to it are more active the second stimulus.
Tilt aftereffect
Fact that there is little to no effect on sensitivity to vertical gratings followeing adaptation to horizontal gratings. Supports that there are individual neurons selective for different orientations.
Selective adaptation
Neurons most sensitive to stimulus become fatigued, so then higher contrast is needed after adaptation in order to stimulate these neurons.
Interocular transfer
The transfer of adaptation from the adapted to the non-adapted eye.
Shows that selective adaptation must happen in cortical neurons.
Spatial frequency channels
Pattern analyzers that are implemented by ensembles of cortical neurons, with each set of cells tuned to a limited range of spatial frequencies and orientations.
What do low frequencies emphasize?
The broad outlines
What do high rrequencies carry in vision?
Informatino about details.
VEP method
Visually evoked electrical potentials.
When is the critical period of early visual development?
3-8 years.
Steropsis
Lack of binocular depth perception
Strabismus
When one eye is turned so that it receives a view from the world in an abnormal angle.
Anisometropia
When two eyes have very different refractive errors.
Superior colluculus
Gets input from the eyes and is very fast and reflexive.
Name the two main classes of retinal ganglion cells:
- Magnocellular / parasol cells (M cells)
- Parvocellular / midget cells (P cells)
Where are the bistratified cells?
In the koniocellular layers.
What is another name for P cells?
Midget cells
What is another name for M cells?
Parasol cells.
Describe the visual pathway of motion/spatial information.
M cells ->
Magnocellular layers ->
4C alpha ->
4C beta ->
thick stripe and dorsolateral, parietal and temporal cortex.
Describe the visual pathway of form information:
P cells ->
parvocellular layer ->
4Cbeta ->
level 2 and 3 interblobs ->
pale interstripe ->
inferior occipitemporal cortex.
Describe the visual pathway of color information:
P cells and bistratified cells ->
parvocellular and intralamirro koniocellular layers ->
4C beta ->
layer 2 and 3 blobs ->
thin stripe ->
inferior occipitotemporal cortex.
What visual pathways go through layer 4b?
Contrast, motion and orientation.
What visual pathways go through the blobs?
Contrast and color
What visual pathways go through the interblobs?
Location, motion (semi), color (semi) and orientation.
What three cell types in the primary visual cortex are called the edge detectors?
- Simple cells
- Complex cells
- Hypercomplex cells.
Where does LGN get input from?
Retinal ganglion cells.
What properties does a simple cell have?
Orientation and position selective.
Why is the position selectivity lost in the complex cell?
It gets input from 3 simple cells which are lined up. The simple cells are slightly different, so when they are all active the complex cell doesn’t know the exast position.
How are receptive field size and eccentricity related?
The further in eccentricity, the larger the receptive fields become.
What are the four elements that determine a grating?
Phase, orientation, spatial frequency and contrast.
Hertz (Hz)
The number of wave cycles per second, the wave’s frequency.
How do oscillations arise?
From interactions between excitatory and inhibitory neural population. At peaks, excitatory population acitivity is highest incl. spike rate.
T1 image
An image of the locations of the atoms, resulting from an fmri procedure.
inhomogeneity
distortion
PD (in mri)
proton density
T1 (in mri)
realignment with magnetic field
T2 (in mri)
proton misalignment due to tissue interactions
TMS
transcranial magnetic stimulation
What are the advantages of EEG?
- Cheap
- High temporal resolution
- Moves with the subject
- Silent
What are the disadvantages of EEG?
- Poor spatial resolution
- Poor signal-to-noise ratio
- Only senses activity near the scalp
- Slow to set up
Give the steps that show why fmri works:
- Deoxyhemoglobin affects T2*
- Blood response follows neural activity
- Step 2 overcompensates
What is the stuff called on which the fmri images depend?
deoxygenated haemoglobin
What happens with the oxyhemoglobin levels when blood flow increases?
The oxyhemoglobin concentration increases.
What happens to the oxyhemoglobin concentration when oxygen is used?
Nothing.
What does the BOLD signal look like following neural activity?
There is an early small dip and then a larger increase.
Lesion
A damaged area of the brain.
What brain area is necessary for motion perception?
Area MT
How does transcranial magnetic stimulation work?
Changing magnetic fields disrupt electrical activity in a specific part of the brain. It can show that activity in that part is necessary for a certain process/task.
Convergence
The way your eyes move together and point inward when you look at nearby objects.
Protanopia
When the L-cone is missing.
Deuteranopia
When the M-cone is missing
Tritanopia
When the S-cone is missing
What determines spacial acuity?
The density of receptors.
Do we perceive light?
No, we perceive changes in light (intensity) across space and or time.
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 are the results of interaction between bits of matter.
Two-point touch threshold
The minimum distance at which two stimuli are just perceptible as separate.
Just noticeable difference (JND)
The smallest detectable difference between two stimuli or the minimum change in a stimulus that enables it to be correctly judged as different from a reference stimulus.
Supertaster
An individual who experiences the most intense taste sensations.
Signal detection theory
A theory where the response of an observer to the presentation of a signal in the presence of noise is quantified. Uses sensitivity and criterion measures.
Criterion (in SDT)
An internal threshold that is set by the observer. If internal response is above criterion, obeserver gives one response and if not, another response.
Sensitivity (SDT)
The ease with which an observer can tell the difference between the presence and absence of a stimulus.
ROC curve (abbreviation)
Receiver operating characteristic curve
ROC curve
The graphical plot of the hit rate as a function of the false alarm rate.
Sine wave
A simple oscillation that repeats across space.
Wavelength
The distance required for one full cycle of oscillation for a sine wave
Period
The time required for a full wavelength of an acoustic sine wave to pass by a point in space.
Phase
A fraction of the cycle of a sine wave described in degrees or radians.
Cranial nerves
Twelve pairs of nerves 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. Axons of the olfactory sensory neurons bundled together, conducts impulses from the olfactory epithelia in the nose to the olfactory bulb.
Optic / II nerves
Second pair of cranial nerves. Arise from retina and carry visual information to the thalamus and other parts of brain.
Vestibulocochlear / VIII nerves
Eigth pair of cranial nerves. Connect the inner ear with the brain, transmitting impulses from hearing and spatial orientation. Composed of cochlear nerve branch and vestibular nerve branch.
Oculomotor / III nerves
Third pair of cranial nerves. Connect to the extrinsic muscles of the eye and the elevator muscle of upper eyelid, ciliary muscle and sphincter muscle of the pupil
Trochlear / IV nerves
Fourth pair of cranial nerves, connect to superior oblique muscles of the eyeballs.
Abducens / VI nerves
Sixth pair of cranial nerves, connect the lateral rectus muscle of the eyeballs.
Polysensory
Blending multiple sensory systems.
Neurotransmitter
A chemical substance used in neuronal communication at synapses.
Neuroimaging
A set of methods that generate images of the structure/ function of the brain.
BOLD signal
The ratio of oxygenated to deoxygenated hemoglobin that permits the localization of brain neurons that are most involved in a task.
Cornea
The transparent ‘window’ into the eyeball.
Aqueous humor
The watery fluid in the anterior chamber of the eye
Lens
The structure inside the eye that enables the changing of focus.
Iris
The coloured part of the eye, consisting of a muscular diaphragm surrounding the pupil and regulating the light entering the eye by expanding and contracting the pupil.
Retina
A light-sensitive membrane in the back of the eye that contains photoreceptors and other cell types that transduce light into electrochemical signals and transmits them to the brain through the optic nerve.
Focal distance
The distance between the lens and the viewed objects, in meters.
What are the most common refractive errors?
Myopia, hyperopia, astigmatism and presbyopia.
Macula
The pigmented region with a diameter of about 5.5mm near the center of the retina.
Rod
A photoreceptor specialized for night vision.
Cone
A photoreceptor specialized for daylight vision, fine visual acuity and colour.
Eccentricity
The distance between the retinal image and the fovea.
Receptive field
The region of the retina in which visual stimuli influence a neuron’s firing rate.
Synaptic terminal
The location where axons terminate at the synapse for transmission of information by the release of a chemical transmitter.
Chromophore
The light-cathing part of the visual pigments of the retina.
Graded potential
An electrical potential that can vary continuously in amplitude.
Horizontal cell
A specialized retinal cell that contacts both photoreceptor and bipolar cells.
Visual acuity
A measure of the finest detail that can be resolved by the eyes.
Midget bipolar cell
A small bipolar cell in the central retina that receives input from a single cone.
Contrast sensitivity function (CSF)
A function describing how the sensitivity to contrast depends on the spatial frequency of the stimulus.
Contrast threshold
The smallest amount of contrast required to detect a pattern.
Lateral geniculate nucleus
A structure in the thalamus that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.
Koniocellular cell
A neuron located between the magnocellular and parvocellular layers of the lateral geniculate nucleus.
Contralateral
Referring to the opposite side of the body
Ipsilateral
Referring to the same side of the body
orientation tuning
The tendency of neurons in striate cortex to respond optimally to certain orientations and less to others.
Extrastriate cortex
A set of visual areas that lie just outside the primary visual (striate) cortex.
RGC
Retinal ganglion cells
When do receptive fields start to show interest in properties important to object recognition?
Beyond V1.
Where are the cells that care about border ownership found?
In area V2.
From what lobe to what lobe is the where pathway?
From the occipital lobe to the parietal lobe.
From what lobe to what lobe is the what pathway?
From the occipital lobe to the temporal lobe.
Lesioned
Surgically removed
Agnosia
Having the ability to see without recognizing what is being seen.
IT cortex (abbreviation)
Inferotemporal cortex.
What cortex is important in agnosia?
The IT cortex.
Grandmother cell
Any cell that seems to be selectively responsive to one specific object.
Homologous regions
Regions that appear to be equivalent in function, but not identical in different species.
Prosopagnosia
The inability to recognize faces.
Reverse-hierarchy theory
Argues that the feed-forward processes give you a general categorical impression of the world, but that you become aware of the details only through feedback.
What is the goal of mid-level vision?
To organize the elements of a visual scene into groups that we can recognize as objects.
Illusory contours
Edges that are perceived even though large parts are missing.
What view is challenged by the existence of illusory contour?
The structuralist view: perception cannot be the sum of atoms of sensations if illusory contour exists.
Gestalt theory
The perceptual whole is more than the sum of its parts.
Gestalt grouping rules
A set of organizing principles that describe the visual system’s interpretation of the raw retinal image.
What are two of the strongest Gestalt principles?
Similarity and proximity
Similarity (Gestalt principle)
Image chunks that are similar to each other will be more likely to group together.
Proximity (Gestalt principle)
Items near each other are more likely to group together than items more widely separated.
What are two weaker Gestalt principles?
Parallellism and symmetry.
Ambiguous figure
A figure that generates two or more plausible interpretations.
Necker cube
A cube where mid-level vision shows two different interpretations, but does not show other interpretations that are also possible.
Accidental viewpoint
When you have to view a scene from one very precise location in order to see a certain interpretation, produces some regularity in the visual image that is not present in the world.
Figure-ground assignment
The process of assigning regions that we see to figure/foreground or background.
Relatability
Whether two contour segments look like they belong to the same edge.
Global superiority effect
Global stuff interferes more with recognition of local stuff than vice versa.
Subtraction method
Used to show the special activation of regions of the cortex to specific stimuli. Sets of stimuli that share one region, then subtract brain activation.
FFA
fusiform face area
EBA
extrastriate body area
Structural description
A specification of an object in terms of its parts and the relationship between parts
Entry-level category
The first word that comes to mind when asked to name a category.
Holistic processing
You don’t recognize parts of a face like someone’sn ose, but the face as a whole.
Congenital prosopagnosia
When someone is born wiht an impariment to recognize faces.
5 principles of mid-level vision
- Bring together wat should be brought together.
- Split what needs to be split.
- Use what you know.
- Avoid accidents.
- Seek consensus and avoid ambiguity.
Recognition-by-components model
A set of geons (geometric ions) could be the basis building blocks of object perception in the world. Visual system recognizes objects by the relationship of its geons.
IT cortex
Part of the cerbral cortex in the lower portion of the temporal lobe, important in object recognition.
Good continuation
A Gestalt grouping rule stating that two elements will tend to group together if they seem to lie on the same contour.
Closure
The Gestalt principle stating that a closed contour is preferred to an open contour.
Texture segmentation
Carving an image into regions of common texture properties.
Parallellism
A rule for figure-ground assignment stating that parallel contours are likely to belong to the same figure.
Symmetry (Gestalt)
A rule for figure-ground assignment stating that symmetrical regions are more likely to be seen as figure.
Surroundedness
A rule for figure-ground assignment stating that is one region is entirely surrounded by another, it is likely that the surrounded region is the figure.
Nonaccidental feature
A feature of an object that is not dependent on the exact viewing position of the observer.
PPA
parahippocampal place area
Parahippocampal place area
A region of extrastriate visual cortex in humans that is specifically and reliably activated more by images of places than by other stimuli.
Fusiform face area
A region of extrastriate visual cortex in humans that is specifically and reliably activated by human faces.
Extrastriate body area
A region of extrastriate visual cortex in humans that is specifically and reliably activated by images of the body other than the face.
Decoding
The process of determining the nature of a stimulus from the pattern of responses measured in the brain or potentially in an ai system.
Template
The internal representation of a stimulus that is used to recognize the stimulus in the world.
Name the three steps to go from physical wavelengths to perception of color:
- Detection
- Discrimination
- Appearance
How many types of cone photoreceptors do we have?
3
At what wavelength do S-cones peak?
420 nm
Around what wavelength do M-cones peak?
535nm
Around what wavelength do L-cones peak?
565 nm
At what light levels do cones work?
Photopic
At what light levels do rods work?
Scotopic light
Around what wavelength do rods peak?
500nm
Principle of univariance
The fact that one type of cone is color blind because it has the same response for different wavelengths, gives ambiguous output.
Trichromacy
The idea that ability to discriminate one light from another is defined in our visual system by the relationships among three numbers.
Metamers
MIxtures of different wavelengths that look identical. Any pair of stimuli that are perceived as identical in spite of physical difference.
What is trichomatric theory often called?
the Young-Helmholtz theory
Additive color mixture
Taking one wavelength or a set of wavelengths and adding it to another, for example red + green = yellow.
Subtractive color mixture
When substance absorbing wavelengths are mixed, thus absorbing more wavelengths and showing a different color.
Maxwell’s color-matching experiment
A color is presented and participants adjust a mixture of three lights (blue, green & red) to obtain the presented color.
What does the nervous system do in order to discriminate colours?
It looks at differences in activity of the three cone types.
Yellow light is equivalent to a mix of…
Long and medium wavelength.
Blue plus yellow light results in a mix of …. and looks …
short, medium and long wavelengths
white
What two differences in cone photoreceptor activity does the nervous system compute?
- (L-M)
- ([L+M]-S)
Cone-opponent cell
A cell where different sources of chromatic information are pitted against each other.
Where do S-cone signals go to?
Through the koniocellular layers in the LGN.
Where do M- and L-cone signals go?
Mostly through the parvocellular layers.
Equiluminant stimuli
Stimuli that vary in color but not in luminance. Bad spatial resolution
Mesopic range
The middle range of light intensities.
HSB (color)
Hue, Saturation and Brightness
CMYK (color)
Cyan, Magenta, Yellow and blacK.
Hering’s opponent colour theory
Has four basic opponent colours: red vs green and blue vs yellow. 3rd pair might be blak vs white. Perception of colour is based on the output of three mechanisms, these opponencies.
Hue cancellation
When you start with a light that appears one colour and add the opponent colour to it, it cancels out the colour it appeared to be.
Unique hue
A hue that can be described with a single colour term.
How many unique hues exist?
4
List the four unique hues
- Red
- Green
- Yellow
- Blue
What colour do very long wavelengths look like?
red
Globs
Colour hot spots in the visual cortex of monkeys
Achromatopsia
Loss of colour vision after brain damage. Vision is largely intact, except for colour experience.
Tetrachromatic colour vision
Is based on four numbers per patch of light, happens in women that have 4 different cone pigments.
Deuteranope
Someone who has no M-cones.
Protanope
Someone who has no L-cones
Tritanope
Someone without S-cones.
Color-anomalous
When someone has three cone photopigments, but two of them are so similar that it is close to having only two cone types.
Cone-monochromat
Someone who has only onte type of cone in the retina.
Rod monochromat
Someone who misses cones altogether. They fail to discriminate colours, have poor acuity and difficulties seeing in daylight conditions.
Anomia
Inability to name.
Color contrast
When the color of one region induces the opponent color in a neighbouring region.
Color assimilation
When two colours bleed into each other, each taking on some of the chromatic quality of the other.
Isolated colour
Unrelated colour
Negative afterimage
If you look at one colour for a few seconds, a subsequently viewed achromatic region will appear to take on a colour opposite to the original colour. First colour is adapting stimulus.
Colour constancy
The tendency for colour of objects to appear relatively unchanged in spite of substantial lighting changes.
Illuminant
The light that illuminates the surface.
Spectral reflectance function
The percentage of each wavelength that is reflected from a particular surface.
Spectral power distribution
The relative amount of light at different visible wavelenghts.
Spectral sensitivity
The sensitivity of a cell or a device to different wavelengths on the electromagnetic spectrum.
Colour space
The three-dimensional space that describes the set of all colours. Established because colour perception is based on outputs of three cone types.
Related colour
A colour that is seen only in relation to other colours. Ex: a gray patch in complete darkness appears white.
Adapting stimulus
A stimulus whose removal produces a change in visual perception or sensitivity.
Neutral point
The point at which an opponent colour mechanism is generating no signal.
`What light colour do S-cones generally respond to?
Blue
What colour of light do M-cones generally respond to?
Green
What colour of light do L-cones generally respond to?
Red.
What is the distribution of cone types in the retina?
About 60% L-cones, 30% M-cones and 10% S-cones.
What does the ratio of activation of cone types tell us?
It gives a description of the of the colour that falls on the retina regardless of brightness.
What does the height of cone activity tell us?
How intense the light is.
What is another term for the magnocellular cells?
Parasol cells
What is another term for the parvocellular cells?
Midget cells
What is another name for the parasol cells?
Magnocellular cells
What is another name for the midget cells?
Parvocellular cells
What is the difference in receptive field size between the two main classes of RGCs?
Magnocellular/parasol cells have large RFs and parvocellular/ midget cells have smaller RFs.
What is the difference in response time for the two main classes of RGCs?
M/parasol cells respons quickly and are good for motion/low-light conditions. P/midget cells respond slowly and give good info about form/shape.
Visual word form area
A brain area that responds to written word.
What is the parvocellular/magnocellular difference in terms of what/where?
Parvocellular is the what-pathway and magnocellular is the where-pathway.
What is the parvocellular/magnocellular difference in terms of the visual info they process?
Parvocellular processes form and color, magnocellular processes motion and space.
What is the parvocellular/magnocellular difference in terms of their function?
Parvocellular serves recognition, magnocellular action.
What is the parvocellular/magnocellular difference in terms of their location?
Parvocellular is ventral, magnocellular is dorsal.
What is the parvocellular/magnocellular difference in terms of their lobes?
Parvocellular through the temporal lobe, magnocellular through the parietal lobe.
What pathway does a ventral lesion affect?
The what-pathway (parvocellular)
What part of the brain is activated in response to objects and faces?
The bottom of the temporal lobe: inferior temporal lobe or IT.
Decoding
THe approach of associating a pattern of brain activity with a particular stimulus or task.
Hypnagogia
The transition to sleep in which people often experience visual imagery much like dreams.
What is the first step between early visual processing and object processing?
Grouping edges.
How does sensitivity to groups of edge patches develop during our life?
Is not present at birth, learned through statistical correlations and increases into the 20s.
Where is the mid-level shape processing area?
The hV4 area and LO1
hV4 area
Lies on or near the inferior occipital gyrus and contains a face selective region.
LO1
Lateral occipital area 1
Distributed encoding
When the activity from a group of neurons yields a result that is interpreted, so one group can create multiple combinations.
Exclusive encoding
When the activation of a single neuron is taken to be interpreted.
Graceful degradation
The ability to (largely) maintain function even though parts are destroyed (in neuron populations)
Deep convolutional network
Tries to imitate the brain’s structure over many levels. Each layer uses input from prior layer and gives input to the next layer.
DCNN
Deep convolutional neural network
List the Gestalt laws of organisation:
- Proximity
- Similarity
- Good continuation
- Closure
- Common fate
- Pragnantz / law of simplicity
Pragnantz
Law of simplicity: group objects because simple or familiar.
Why do Gestalt laws work?
They reflect assumptions about the nature of real-world surfaces and objects.
Realism
The philosophical position that there is a real world to sense.
Positivism
The philosophical position that all we really have to go on is the evidence of our senses, so the world could be an elaborate hallucination.
What happens to the retinal image of an object as the object gets further away from the eye?
It gets smaller.
Lateral eyes
Eyes on the side of the head, some animals have this.
Frontal eyes
When eyes are positioned like humans, facing one direction.
How many degrees is our human visual field from left to right?
190 degrees
What part of our horizontal visual field can be seen by both eyes?
110 degrees out of the 190 degrees.
How big is our human visual field from up to down?
140 degrees
How is our vertical visual field partitioned?
Abot 60 degrees up untill your eyebrows block the view, and 40 degrees down to the cheeks.
Binocular
Referring to two eyes.
Probability summation (vision)
The increased detection probability based on the statistical advantage of having two (or more) detectors rather than one
Binocular summation
the combination of signals from both eyes in ways that make performance on many tasks better than with either eye alone.
Binocular disparity
the differences between the two retinal images of the same scene.
Stereopsis
A vivid perception of the three-dimensionality in the world, the binocular perception of depth.
Is stereopsis available with monocular vision?
no
Monocular
Referring to one eye
Monocular depth cue
a depth cue that is availble even when the world is viewed with one eye alone
Binocular depth cue
a depth cue that relies on information from both eyes.
Pictorial depth cues
A cue to distance or depth used by artists to depict three-dimensional depth in two-dimensional pictures.
Why is it we can see depth in two-dimensional pictures?
The retinal image formed by the two-dimensional picture is the same as the one that would have been formed by the 3d world + depth cues.
Occlusion (depth cue)
A nonmetrical depth cue to relative depth order, present in almost every visual scene.
Nonmetrical depth cue
A depth cue that provides information about the depth order (relative depth), but not the absolute depth.
Projective geometry
the geometry that describes the transformations that occur when the three-dimensional world is projected onto a two-dimensional surface.
Relative size (depth cue)
The comparison between items without knowing the absolute size of either one.
Texture gradient
A depth cue based on the geometric fact that items of the same size form smaller images when they are further away.
Metrical depth cue
A depth cue that provides quantitative information about distance in the third dimension.
Familiar size (depth cue)
A depth cue based on knowledge of the typical sizes of objects.
Relative metrical depth cue
A depth cue that could specify the relationship between distances bt not the absolute distance.
Absolute metrical depth cue
A depth cue that provides quantifiable information about distance in the third dimension.
What is another word for aerial perspective?
Haze
What is another word for haze?
Aerial perspective
Aerial perspective
A depth cue based on the implicit understanding that light is scattered by the atmosphere. More light is scattered when we look through more atmosphere so more distant objects are subject to more scatter and appear fainter, bluer and less distinct.
Linear perspective
A depth cue based on the fact that lines are parallel in the three-dimensional world will appear to converge in a two-dimensional image.
Vanishing point
The apparent point at which parallel lines receding in depth converge.
Anamorphic art
Art where the two-dimensional image is recognizable only from an unusual vantage point.
Anamorphosis
The use of the rule of linear perspective to create a two-dimensional image so distorted that it looks correct only from a special angle or with a mirror.
Triangulation cues
Depth cues that cannot be reproduced in a static two-dimensional picture.
Motion parallax
A depth cue based on head movement. Geometric information from one eye in two positions at two times is similar to the info from two eyes in two positions at one time.
Optic flow
The pattern of apparent motion of objects in a visual scene produced by the relative motion between the observer and the scene.
Divergence
The ability of the eyes to turn outward.
Corresponding retinal points
Two monocular images of an object in the world are said to fall on corresponding points if those points are the same distance from the fovea in both eyes. The two foveas are also corresponding points.
Vieth-Müller circle
The location of objects whose images fall on geometrically corresponding points in the two retinas.
Horopter
The location of objects whose images lie on corresponding points.
Surface of zero disparity
the horopter
Are the horopter and the Vieth-Müller circle the same?
Not quite.
Diplopia
Double vision
Panum’s fusional area
The region of space in front of and behind the horopter within which binocular single vision.
Crossed disparity
The sign of disparity created by objects in front of the horopter.
Uncrossed disparity
The sign of disparity created by object behind the horopter.
What happens to the horopter if we change our fixation?
It moves to a different location in space.
Stereoscope
A device for simultaneously presenting one image to one eye and another image to the other eye.
Free fusion
The technique of converging (crossing) or diverging the eyes in order to view a stereogram without a stereoscope.
Stereoblindness
An inability to make use of binocular disparity as a depth cue.
RDS (abbreviation)
random dot stereogram
Random dot stereogram (RDS)
A stereogram made of a large number of randomly placed dots, contains no monocular cues to depth.
Cyclopean stimuli
Defined by binocular disparity alone.
Correspondence problem
The problem of figuring out which bit of the image in the left eye should be matched with which bit in the right eye.
Uniqueness constraint
The observation that a feature of the world is represented exactly once in each retinal image.
Continuity constraint
The observation that, ecept at the edges of objects, neighbouring points in the world lie at similar distances from the viewer.
Binocular rivalry
The competition between the two eyes for control of visual perception, which is evident when completely different stimuli are presetnted to the twoeyes.
Until when are infants blind to disparity?
Until 3-4 months
When are infants sensitive to depth based on pictorial cues?
From 6 months and on.
Stereoacuity
A measure of the smallest binocular disparity that can generate a sensation of depth.
Esotropia
Strabismus in which one eye deviates inward.
Exotropia
Strabismus in which one eye deviates outward.
Tilt aftereffect
the perceptual illusion of tilt, produced by adaptation to a pattern of given orientation.
Interocular transfer
Transfer of the effect from one eye to the other.
Surpression (vision)
INhibition of unwanted images.
What are the monocular depth cues?
- Occlusion
- Various size and position cues
- Aerial perspective
- Linear perspective
- Motion cues
- Accomodation
- Convergence
External attention
Attention to stimuli in the world
Internal attention
Our ability to attend to one line of thought as opposed to another, or to select one response over another.
Overt attention
Directing a sense organ at a stimulus.
Covert attention
For example, looking at a page while directing attention to a person at your side
Attention
Any of the very large set of selective processes in the brain.
Selective attention
The form of attention involved when processing is restricted to a subset of the possible stimuli
RT (abbreviation)
reaction time
Reaction time
A measure of the time from the onset of a stimulus to a response.
Cue (in RT experiments)
A stimulus that might indicate where (or what) a subsequent stimulus will be. Can be valid, invalid or neutral.
What is the difference in reaction time for valid vs invalid cues?
RT decreases with valid cues and increases with invalid cues.
Exogenous cue
A cue that is located out (exo) at the desired final location of attention.
Endogenous cue
A cue that is located in (endo) or near the current location of attention
Peripheral cue
Exogenous cue
Symbolic cue
Endogenous cue
SOA (abbreviation)
stimulus onset asychrony
Stimulus onset asychrony (SOA)
The time between the onset of one stimulus and the onset of another.
Probe
Target stimulus
Inhibition of return (in attention)
The relative difficulty in getting attention (or the eyes) to move back to a recently attended (or fixated) location.
Visual search
A search for a target in a display containing distracting elements.
Target (in visual search)
The goal of a visual search.
Distractor (in visual search)
Any stimulus other than the target.
Set size (in visual search)
The number of items in a visual display.
How is the efficiency of a search task described?
By the slope of the function relating RT to set size. Higher slope = lower efficiency.
Feature search
Search for a target defined by a single attribute (ex: color or orientation).
Salience
The vividness of a stimulus relative to its neighbors.
Parallel search
A search in which multiple stimuli are processed at the same time.
RT does not change with the set size, thus the slope relating RT to set size is about flat, 0ms per item.
Serial self-terminating search
A search from item to item, ending when a target is found.
What does it mean when a visual search is inefficient?
Each additional item in the display imposes a significant cost on the researcher.
Guided search
A search in which attention can be restricted to a subset of possible items on the basis of information about the target item’s basic features (ex: color).
Conjunction search
A search for a target defined by the presence of two or more attributes.
Scene-based guidance
Information in our understanding of scenes that helps us find specific objects in scenes.
Binding problem
The challenge of tying different attributes of visual stimuli which are handled by different brain circuits to the appropriate object so that we perceive a unified object.
Feature integration theory
Anne Treisman’s theory of visual attention, which holds that a limited set of basic features can be processed in parallel preattentively, but other properties including the correct binding of features to objects, require attention.
Preattentive stage
The processing of a stimulus that occurs before selective attention is deployed to that stimulus.
Illusory conjunction
An erroneous combination of two features in a visual scene (ex: seeing red X when display has red letters and Xs but no red Xs).
RVSP (abbreviation)
rapid serial visual presentation
Rapid serial visual presentation (RSVP)
An experimental procedure in which stimuli appear in a stream at one location at a rapid rate.
AB (abbreviation)
attentional blink
Attentional blink (AB)
The tendency not to perceive or respond to the second of two different target stimuli amid a rapid stream of distracting stimuli if the observer has responded to the first target stimulus 200-500 ms before the 2nd stimulus is presented.
Response enhancement
An effect of attention on the response of a neuron in which the neuron responding to an attended stimulus gives a bigger response
Sharper tuning
An effect of attention on the response of a neuron in which the neuron responding to an attended stimulus responds more precisely.
Visual-field defect
A portion of the visual field with no vision or with abnormal vision, typically resulting from damage to the visual nervous system.
Neglect
The inability to attend or respond to stimuli in the contralesional visual field, or ignoring half of the body or half of an object.
Contralesional field
The visual field on the side oppsite a brain lesion
Extinction
The inability to perceive a stimulus to one side of the point of fixation in the presence of another stimulus, typically in a comparable position in the other visual field
Ipsilesional field
The visual field on the same side as a brain lesion
ADHD (abbreviation)
Attentional deficit hyperactivity disorder
Ensemble statistics
The average and distribution of properties like orientation or color over a set of objects or over a region in a scene. Our estimates of ensemble statistics are surprisingly accurate.
Spatial layout
The description of the structure of a scene without reference to the identity of specific objects in the scene.
Change blindness
The failure to notice a change between two scenes. If the gist, or meaning, of the scene is not altered, quite large changes can pass unnoticed.
Inattentional blindness
A failure to notice -or at least to report- a stimulus that would be easily reportable if it were attended.
Hypercomplex cell
The ‘angle detector’. Is orientation selective, has endstopping and gets input from the complex cells.
