Midterm 1 Flashcards
What is the perceptual process?
The steps we take (seven) plus “knowledge” inside our head to summarize the major events that occur in the environment
What are the first two steps of the perceptual process?
Stimuli i.e. Environmental stimulus - the tree that the person is observing
What is the principle of transformation?
Stimuli and responses created by stimuli are transformed or changed, between the environmental stimulus and perception
When a reflected light reaches the eye, it is transformed as it is focused by the eye’s optical system, which is the __ at the front of the eye and the __ directly behind it. If these optics are working properly, they form a sharp image of the tree on the __ of the person’s __, a 0.4-mm thick network of nerve cells that covers the back of the eye
Cornea; lens; receptors; retina
What is the principle of representation?
Everything a person perceives is based not on direct contact with stimuli but on representations of stimuli that are formed on the receptors and on activity in the person’s nervous system
__ are cells specialized to respond to environmental energy, with each sensory system’s receptors specialized to respond to a specific type of energy
Sensory receptors
__ receptors respond to light, __ receptors to pressure changes in the air, __ receptors to pressure transmitted through the skin, and __ & __ receptors to chemicals entering the nose and mouth
Light; auditory; touch, smell taste
When the visual receptors that line the back of the eye receive the light reflected from the tree, what two things do they do?
- Transform environmental energy into electrical energy
2. They shape perception by the way they respond to stimuli
The transformation of one form of energy (i.e. light energy) to another form (i.e. electrical energy) is called __
Transduction
Electrical signals from each sense arrive t the __ for that sense in the cerebral cortex of the brain
Primary receiving area
The __ is a 2-mm thick layer that contains the machinery for creating perceptions, language, memory, and thinking
Cerebral cortex
The primary receiving area for vision occupies most of the __ lobe; the area for hearing is located in part of the __ lobe; and the area for the skin senses - touch temperature and pain is located in an area in the __ lobe
Occipital; temporal; parietal
The __ lobe receives signals from all of the senses, and it plays an important role in perceptions that involve the coordination of information received through two or more senses
Frontal
__ involves the interactions between the signals traveling in networks of neurons early in the system, in the retina; later, on the pathway to the brain; and finally within the brain
Neural processing
__ which is conscious awareness of the object (i.e. tree), and __, which is placing an object in a category, such as a “tree” that gives it meaning
Perception; recognition
What is visual form agnosia?
An inability to recognize objects i.e. may be able to perceive the object and recognize parts of it - but cannot recognize it as a whole
The final behavioral response is __, which involves motor activities
Action i.e. walk toward the tree or climb it
__ processing is processing that is based on the stimuli reaching the receptors; __ processing refers to processing that is based on knowledge
Bottom-up; top-down
The __ approach measures the relationship between the stimuli and the behavioral response
Psychophysical
Horizontal and vertical lines (stimuli) resulted in better detail vision (the behavioral response) than slanted lines, this detail vision is called the __
Oblique effect
The __ approach involves measuring two relationships, the relationship between stimuli (steps 1-2) and physiological responses (steps 3-4)
Physiological approach
__ is the minimum stimulus intensity that can just be detected
Absolute threshold
What is the method of limits (Fechner’s classical psychophysical methods)?
The experimenter presents stimuli in either ascending order (intensity increased) or descending order (intensity decreased) which indicates the results of an experiment that measure’s a person’s threshold for hearing a tone
What is the method of adjustment?
The stimulus intensity is either increased or decreased until the stimulus can just be detected. However, the observer adjusts the stimulus intensity continuously until he/she can barely detect the stimulus
What is the method of constant stimuli?
The experimenter presents 5 to 9 stimuli with different intensities in random order. On each trial, observer says yes or no to indicate whether he/she sees the light
Which method of the method of limits is the most accurate?
the method of constant stimuli, because it involves many observations and stimuli are presented in random order
Disadvantage - Time-consuming
What is the difference threshold?
The smallest amount by which two sensory stimuli can differ in order for someone to perceive them as different
What is the magnitude estimation experiment?
Requires subjects to estimate the magnitude of physical stimuli by assigning numerical values proportional to the stimulus magnitude they PERCEIVE
- perceived magnitude
When the increased perceived magnitude is SMALLER than the increase in stimulus intensity, it is called __
Response compression
As intensity is increased, perceptual magnitude increases more than intensity. This is called __
Response expansion
One way to measure behavioral response to a stimulus is the __, in which a person is asked to describe what he or she is perceiving or to indicate when a particular perception occurs
Phenomenological method
What is visual search?
Finding one stimulus among many, as quickly as possible i.e. searching for a friend’s face in a crowd
__ is the time between presentation of the stimulus and the observer’s response to the stimulus
Reaction time
The energy in the electromagnetic spectrum can be described by its __ - the distance between the peaks of the electromagnetic vages
Wavelength
Visible light, the energy within the electromagnetic spectrum that humans can perceive, has wavelengths ranging from about __ nanometers
400-700
Light can be described as consisting of small packets of energy called __
Photons (one photon - smallest possible packet)
Light reflected from the objects in the environment enters the eye through the __ and is focused by the __ and __ to form sharp images of the objects on the __, the network of neurons that covers the back of the eye and that contains the receptors for vision
Pupil; cornea; lens; retina
What are rods and cones?
Visual receptors that contain light-sensitive chemicals called visual pigments that react to light and trigger electrical signals
__ is the change in the lens’s shape that occurs when the ciliary muscles at the front of the eye tighten and increase the curvature of the lens so that it gets thicker
Accommodation
The distance at which your lens can no longer accommodate to bring close objects into focus is called the __
Near point
What is presbyopia?
The distance of the near point increases as a person gets older
- most 20 year olds is about 10cm
What is myopia, or nearsightedness?
Inability to see distant objects clearly
What is refractive myopia?
The cornea and/or lens bends the light too much
What is axial myopia?
The eyeball is too long
The distance at which light becomes focused on the retina is called the __
Far point; when the object is at the far point, a person with myopia can see it clearly
What is hyperopia, or farsightedness?
The ability to see distant objects clearly but has trouble seeing nearby objects
In the __ eye, the focus point for parallel rays of light is located behind the retina, usually because the eyeball is too short
Hyperopic
What is transduction?
The transformation of one form of energy into another form of energy
vision - light energy into electrical energy
Visual pigments have two parts:
1) A long protein called opsin
2) Smaller light-sensitive component called retinal
The retinal change of shape, from being bent, to straight is called __, which creates a chemical reaction that activates thousands of charged molecules to create electrical signals in receptors
Isomerization
The process of increasing sensitivity in the dark by increasing its sensitivity to light is called __
Dark adaptation
One small area, the __ contains only cones. When we look directly at an object, the object’s image falls on it
Fovea
The __, which includes all of the retina outside of the fovea, contains both rods and cones
Peripheral retina
There are about 120 million __ and only 6 million __ in the retina
Rods; cones
What is macular degeneration?
Most common in older people, destroys the cone-rich fovea and a small area that surrounds it
- this creates a blind region in central vision
__ is a degeneration of the retina that is passed from one generation to the next. It first attacks the peripheral rod receptors and results in poor vision in the PERIPHERAL VISUAL FIELD
Retinitis pigmentosa
The absence of receptors is called the __. You are not normally aware of it
Blind spot
The first step in the study of adaptation is to measure the __ which is the function relating sensitivity to light to time in the dark, beginning when lights are extinguished
Dark adaptation curve
People who have no cones due to a rare genetic defect, are called __
Rod monochromats
The change in shape and separation from the opsin causes the molecule to become lighter in color, a process called __
Visual pigment bleaching
Our sensitivity to light depends on the concentration of a chemical:
The visual pigment
The speed at which our sensitivity increases in the dark depends on a chemical reaction:
The regeneration of the visual pigment
What is spectral sensitivity curves?
The relationship between wavelength and sensitivity
The enhanced perception of short wavelengths during dark adaptation is called the __
Purkinje shift
A pigment’s __ is a plot of the amount of light absorbed versus the wavelength of the light
Absorption spectrum
Electrical signals occur in structures called __
Neurons
__, which branch out from the cell body (keeps the cell alive) to receive electrical signals from other neurons
Dendrites
The __ or __ which is filled with fluid that conducts electrical signals
Axon / nerve fiber
-70 millivolts; stays the same as long as there are no signals in the neuron, is called the __
Resting potential
An important property of the action potential is that it is a __- once the response is triggered, it travels all the way down the axon without decreasing in size
Propagated response
What is the refractory period?
The interval between the time one nerve impulse occurs and the next one can be generated in the axon
Action potentials that occur in the absence of stimuli from the environment are called __
Spontaneous activity
An excitatory response occurs when the inside of the neuron becomes more positive, a process called __
Depolarization
An inhibitory response occurs when the inside of the neuron becomes more negative, a process called __
Hyperpolarization
__ occurs when a number of neurons synapse onto a single neuron –> each eye has 126 million receptors but only 1 million ganglion cells
Convergence
__- interconnected groups of neurons within the retina, signals generated in the receptors travel to the bipolar cells and then to the ganglion cells
Neural circuits
The greater convergence of the rods compared to the cones translates into two differences in perception:
1) The rods result in better sensitivity than the cones
2) The cones result in better detail vision than the rods
While rod vision is more sensitive than cone vision because the rods have more convergence, the cones have better __ because they have LESS convergence
Visual acuity –> refers to the ability to see details
Your visual acuity is highest in the __
Fovea; objects that are imaged on the peripheral retina are not seen as clearly
Measuring an electrical signal called the __, which is recorded by disc electrodes placed on the infant’s head over the visual cortex
Visual evoked potential (VEP)
What is lateral inhibition?
Inhibition that is transmitted across the retina
- Keffer et al used the Limulus to demonstrate how lateral inhibition can affect the response of neurons in a circuit
- Limulus eye is made up of hundreds of tiny structures called ommatidia
How can Mach bands be explained by lateral inhibition?
Each of the six receptors in a circuit sends signals to bipolar cells, and each bipolar cell sends lateral inhibition to its neighbors on both sides
__ occurs when our perception of the brightness or color of one area is affected by the presence of an adjacent or surrounding area
Simultaneous contrast
What is belongingness?
States that an area’s appearance is influenced by the part of the surroundings to which the area appears to belong
The receptive field is always on the __. It doesn’t matter where the neuron is- it could be in the retina, visual cortex, or elsewhere in the brain, but the receptive field is always on this location because that is where the stimuli are received
Retina
__ cells respond to small spots of light or to stationary stimuli (vertical that covers the excitatory area of the receptive field), whereas __ cells respond only when a correctly oriented bar of light moves across the entire receptive field
Simple; complex
__ cells fire to moving lines of a specific length or to moving corners or angles
End-stopped
Because simple, complex, and end-stopped cells fire in response to specific features of the stimulus, such as orientation or direction of movement they are sometimes called __
Feature detectors
Which type of cell?
Center-surround receptive field, responds best to small spots, but will also respond to other stimuli
Optic nerve fiber (ganglion cell)
Which type of cell?
Center-surround receptive fields very similar to the receptive field of a ganglion cell
Lateral geniculate
What is selective adaptation?
- psychophysical procedure to measure the physiology-perception relationship
- firing causes neurons to eventually become fatigued or adapt
The adaptation of selective adaptation causes two physiological effects:
1) The neuron’s firing rate decreases
2) The neuron fires less when that stimulus is immediately presented again
A grating’s __ is the minimum intensity difference between two adjacent bars that can just be detected. The contrast threshold for seeing a grating is measured by changing the INTENSITY DIFFERENCE between light and dark bars until the bars can just barely be seen
Contrast threshold
What is selective rearing?
If an animal is reared in an environment that contains only certain types of stimuli, then neurons that respond to these stimuli will become more prevalent
What is neural plasticity / experience-dependent plasticity?
The idea that the response properties of neurons can be shaped by perceptual experience
Which location of the the brain is rich in neurons that respond to faces in monkeys and humans?
Monkeys: Inferotemporal (IT) cortex –> temporal lobe
Humans: Fusiform face area (FFA) –> just under temporal lobe
__ proposes that a particular object is represented by the firing of a neuron that responds ONLY to that object and to no other objects
Specificity coding
What is a grandmother cell?
A neuron that responds only to a specific stimulus. This stimulus could be a specific image or concept
__ is the representation of a particular object by the pattern of firing of a large number of neurons
Distributed coding
Advantage: large number of stimuli can be represented and create different patterns
__ occurs when an object is represented by a pattern of firing of only a SMALL group of neurons, with the majority of neurons remaining silent
Sparse coding
__ refers to the way stimuli at specific locations in the environment are represented by activity at specific locations in the nervous system
Spatial organization
The electronic map of the retina on the cortex is called a __. It means that two points that are close together on an object and on the retina will ACTIVATE NEURONS that are close together in the brain
Retinotopic map
The apportioning to the small fovea of a large area on the cortex is called __
Cortical magnification
A location column with all of its orientation columns is called a __, and it receives information about all possible orientations that fall within a small area of the retina
Hypercolumn
When columns COVERS the entire visual field, it is an effect called __
Tiling
__ refers to the destruction or removal of tissue in the nervous system
Ablation
The __ pathway is also called the ‘what’ pathway, and the __ pathway is called the ‘where’ or ‘how’ pathway
Ventral; dorsal
If you have difficulty naming objects but have no trouble indicated where they are located, you have damage to your:
Temporal lobe (where is the object)
If you have difficulty indicating where objects are located, but you can identify the objects just fine, you have damage to your:
Parietal lobe (what is the object)
A structure that is specialized to process information about a particular type of stimulus is called a __
Module
The parahippocampal place area (PPA) is activated by pictures depicting __
Indoor and outdoor scenes
The extrastriate body are (EBA) is activated by pictures of __
Bodies and parts of bodies (BUT NOT FACES)
The task of determining the object responsible for a particular image on the retina is called the __
Inverse projection problem
The ability to recognize an object seen from different viewpoints is called __
Viewpoint invariance
__ is the process by which elements in the environment become perceptually grouped to create our perception of objects
Perceptual organization
What is grouping?
Visual events are “put together” into units or objcts
What is segregation?
Separating one area or object from another
What are illusory contours?
We see edges that aren’t actually there
What is the principle of similarity?
Similar things appear to be grouped together
What is the priniciple of proximity?
Things that are near each other appear to be grouped together
What is the principle of common fate?
Things that are moving in the same direction appear to be grouped together
i.e. flock of birds
What is the principle of common region?
Elements that are within the same region of space appear to be grouped together
i.e. circles inside ovals; seeing circles as belonging together
What is principle of uniform connectedness?
Connected region of the same visual properties i.e. lightness, color, texture, etc perceived as a single unit
