The Brain
What cognitive tasks are typically associated with the left hemisphere? Right hemisphere?
Left: language, logic, analytical thoughts, purposeful movements, right side of the body
Right: art, music, perceiving emotions, facial recognition, spatial relations, creativity, processing the whole, left side of the body
Distinguish between top-down and bottom-up information
Top-down: begins with knowledge and expectations (from your brain to your body)
Bottom-up: begins with sensory information, from your skin to your brain
What impairments did you read about in “The Man Who Mistook His Wife for a Hat”?
This man has visual agnosia and has trouble recognizing his wife and other objects
How is the field of Cognitive Psychology and Cognitive Neuroscience defined?
Cognitive psychology: the study of how the mind works, acquires, transforms, retains, utilizes and communicates information
Cognitive Neuroscience: the study of the biological basis for cognitive functioning (mapping of cognitive processes to brain structures)
What are the three types of color blindness?
Trichromats: normal color vision
Dichromats: red-green color blindness, red cones filled with green photopigment, or vice versa, more common in males due to x linked inheritance
Monochromats: cannot distinguish between colors, only brightness, one cone type, rods only.
What is the modularity hypothesis? Give an example of what this may look like.
The brain has specialization of certain things, it is arranged or specified into certain modules.
For example, when someone has a stroke damaging their brocas area in their frontal lobe, they may have trouble speaking, which would imply that the area in the frontal lobe known as the brocas area is responsible for a certain function, and the same concept goes for the rest of the brain
Provide an argument for and against the grandmother cell hypothesis.
There aren’t enough cells for that, and cells also die over time, however complex cells feed into hypercomplex cells, which are sensitive to some types of visual forms, ex. in monkeys this process produced cells that respond to money faces
Describe the impairment associated with unilateral neglect, and give an example of this.
Patients ignore information on one side of their visual field (the opposite side of their brain damage) related to attention.
Think of the woman only eating from half of her plate in eyes right, and how she has to rotate the plate to eat the food
Describe the Resonance Hypothesis and how it’s related to mental awareness.
Cell firing rates change quite a bit, but eventually the rates will stop changing so much, the remaining active cells are left supporting each other’s activity through excitation, while inactive cells are inhibited by active cells (just like the demo), and finally resonance occurs when we see a final steady pattern of activation which results in mental awareness
What is the blind spot? Why aren’t we usually aware of our blind spot? Where is the blind spot on the eye?
-items of interest fall of the fovea
-we typically view the world with two eyes
-we use top-down info to fill in missing info
Blind spot falls where the optic nerve is, at the back of the eye. This is the spot on the eye where light is not visible, even if it hits the spot.
What is the primary somatosensory area? How is it organized in relation to regions of the body?
Part of the brain organizing and separating the sensory and motor cortex, topographically organizing parts of the body based on their distance from their brain, disproportionately sensitive depending on the size of the body part
What is brightness contrast? Explain brightness contrast using what we know about receptive fields.
Brightness contrast is where the visual system computes brightness using context, like the context of a corner. Receptive fields on the corner receive the same excitation at the center, differ inhibition in the surround, allowing you to perceive a contrast in brightness
Describe Korte’s Law in relation to apparent motion. What stimulus properties are important in creating convincing apparent motion and what is ISI?
Kortes’s Law (1915): noted that the ISI needs to increase when the distance between stimulus increases to perceive good motion. If the ISI is too brief, it will appear that there are two simultaneous flashes happening at once, and an ISI that is too long will look like one flash, then the other, and there will be no motion.
ISI, distance between stimulus, and stimulus intensity are all important.
ISI: the timing of which the flashes were presented which is important in creating the illusion.
How do neural networks learn?
Networks respond to input depending on connection weight (Hebb’s Rule). A network doesn’t need intelligence to set connection weights, it self organizes all of that in response to stimulation, and can remember those things it has experienced for later. This can also help it interpret new information based on old experiences
Describe the lens, how the picture is projected on the retina, and how accommodation is used in the lens
the lens is the flexible tissue that helps focus an image onto the retina, of which is projected upside down and backwards. Accommodation basically is pressure building in your eye when your lens changes shape in order to focus on an image
What is contralateral processing? What part of the brain connects the hemispheres? What happens to contralateral processing in split brain patients?
Definition: processing in the brain is done on the opposite sides of your organs, so your left hemisphere controls functions on the right and in the right visual field, and the right hemisphere controls the opposite
The corpus callosum- bundle of neural fibers
Split brain patients can’t have contralateral processing because there is only one hemisphere, so their brain uses neural plasticity to rearrange to brains responsibilities to make up for the missing functions of the hemisphere they are missing.
Describe Trichromatic Color Theory. What does it easily account for? What does it have trouble accounting for?
three types of cones in retina, each maximally sensitive to one range of wavelengths
-blue (short)
-green (medium)
-red (long)
Colors are sensed by the amount of activation coming from each wavelength type, deciding what color you perceive
What are the four ways we perceive motion?
Real motion, apparent motion, induced motion, motion aftereffect
real motion requires some actual movement to be happening, and the threshold for this to be noticed is 1/6 of a degree of visual angle per second, but it varies depending on the context. Apparent motion on the other hand requires no motion at all, and is comprised of Interstimulus intervals which expand or decrease the duration between one flash and another, the distance between flashes, and the intensity of the stimulus all play a role in the illusion of movement.
List and describe the assumptions that we rely on in cognitive psychology
Mental events exist
Mental events can be studied
Mental processes take time
There is a limited processing capacity
Cognition is fundamentally an active, constructive, and hence biased process (bias because it’s a result of our past) (like continuous and automatic functions occurring)(your brain can only process so much)
A fundamental problem is computational complexity- too much information, too many possibilities
A lot of cognition can be understood in terms of strategies used to cope with computational complexity
Cognitive processes are interrelated (it doesn’t just take one functioning part of the brain for an action or idea to happen)
We are unaware of the majority of cognitive operations (that are going on that we don’t even know about, there is so much left to study)
Describe the receptive fields of on-center off-surround cells, off-center on surround cells, simple cells, and complex cells.
on-center, off-surround: respond well to small spots of lights, responds OK to some edges and corners, does not respond well to homogeneous (uniform) field of lights
off-center, on surround: opposite arrangement, focus away from the center only
simple cells: sensitive to bars or edges of a preferred orientation at a particular location
complex cells: respond to particularly oriented bars of light, but responds best when the bar of light moves across the receptive field
List the five major areas (and any of their substructures) of the forebrain and cortex as discussed. Briefly describe each of the structures functions.
Describe The Opponent Process Theory of Color. What does it really account for?
these colors get fatigued over time, and then the opponent color will win which is why after staring at a picture, and then looking away, the colors will flip. When you see a color in the world, it just means that thing contains an overwhelming amount of that color wavelength.
red vs. green
blue vs. yellow
white vs. black
Identify and describe the oculomotor, monocular, and binocular cues to depth perception that we discussed in class
Oculomotor cues: convergence, accommodation
Monocular cues: occlusion, relative size, relative height, linear height, familiar size, shadows, texture gradient, atmospheric perspective, motion produced cues
Binocular cues: retinal disparity
Identify and describe the key properties of neural network behavior that distinguish neural networks from individual neurons.
Describe the visual pathway starting from light energy in the environment and ending in the visual cortex.
Lens-> Retina-> Rods and Cones->Bipolar cells-> Convergence-> Optic Nerve-> Optic Chiasm-> LGN-> Superior Colliculus-> Primary Visual Area of the Occipital Lobe