Exam 1 Deck Flashcards
Perception Exam 1 Flashcards
What is Intuition?
Our senses give us a true representations of the world and the things in it as they are
– We interpret those representations and make decisions based on them
– We can trust the information that we get from our senses
Is there stuff our senses can’t pick up?
Yes
Is it possible for our senses to be confused by what something is?
Yes, sometimes our perceptual system gives us conflicting information. We can’t tell what’s really there.
Can experience change our perception of something even if the thing itself does not change?
This would not be true if what our senses was giving us was a simple reflection of the world as it is. Our experiences don’t change the world, but do change our perception of it.
Can we perceive things that are not there?
Yes we can.
We can not perceive things that are actually there. (T/F)
True
Can our perceptual system get confused?
Yes, we can see things happening that are not actually happening. Or see things as different colors that are actually the same color.
What is the Necker cube?
The Necker cube – A 'bistable' figure • Two different, incompatible interpretations – It is never ambiguous • Always one or the other percept • Flips between the two
What is the Kaniza triangle?
– An apparent upside down white triangle occluding a rightside up black triangle and three black disks
• Classic example of ‘illusory contours’
Perception is a passive process. (T/F)
False, it is not a passive process.
Perception is an action that is done by the perceiver. (T/F)
True, in order to perceive something we have to actively be trying.
What is perception to the perceiver?
The action to create a computed representation that estimates (a best guess) of the nature of an energy source in the environment by an organic computer (the brain).
What is the retinal network?
• The retina is brain network made of neurons
– Rods and Cone transduce
– Bipolar cells transmit signal to ganglion cells
– Ganglion cells output to brain
– Horizontal & amacrine cells connect laterally
• This network can do computations
What are Mach Bands?
An optical illusion named after the physicist Ernst Mach. It exaggerates the contrast between edges of the slightly differing shades of gray, as soon as they get in contact with each other, thus enhancing edge-detection by the human visual system.
What is real vs. what is perceived by Mach Bands
• What's Real – A Stairstep pattern • Uniform intensity across color patch • What's Perceived – Stairs with ‘spikes’ at the boundaries • Bands of lighter and darker intensity where the color patches meet
What does the visual system have to do?
• What does the visual system have to do?
– Discriminate one thing from another
• What distinguishes objects?
– Their boundaries
• Lateral inhibition enhances edge perception above what is really there
Mach Bands: A Bio-Cogno-Psycho-Physical Approach… What is the Physical?
• Physical
– Patches of uniform intensity adjacent to patches of different intensity
Mach Bands: A Bio-Cogno-Psycho-Physical Approach… What is the Psychological?
• Psychological
– Perception of lighter and darker intensity bands at patch boundaries
Mach Bands: A Bio-Cogno-Psycho-Physical Approach… What is the Cognitive?
• Cognitive Model
– A computational network of convergent input with lateral inhibition
Mach Bands: A Bio-Cogno-Psycho-Physical Approach… What is the Biological?
• Biological
– The retinal mosaic has horizontal cells connected between receptors and ganglion cells to provide convergence with lateral inhibition
What is sensation?
– Sensation: The impact of the external world on specialized receptors on the body
What is percept?
– Percept: an internal representation of something in the world
What is perception?
– Perception: the process of forming that internal
representation
What is the internal representation?
• That internal representation is not a direct reflection of external reality but rather the brain’s computed estimate of the source of environmental stimulation modified to be optimally adaptive
– If an organism is more likely to survive by seeing something that isn’t there or not seeing something that is, then that’s the output the perceptual system returns
What is dualism?
• Note part of Matrix quote: “electrical signals interpreted by your brain”
• Implies there are two things: electrical signals, and something that interprets those electrical signals
– Note here they use the term “brain” for the interpreter to try to avoid the appearance of dualism, but it’s the same a saying “mind”
• This is our intuition, that there is a “true me” (whatever you call it: mind/spirit/soul) that can observe perceptions formed in the brain and can control “my” body (mechanical/meat) like a puppeteer pulling strings
– The mind and body are two separate and distinct things
• Mind: ethereal (not of the physical world)
• Body: corporeal (of the physical world)
René DesCartes and dualism
• Developed a theory of the relationship between mind and body known as Cartesian Dualism
– Based on hydraulic theory of nervous system
• (Also invented Cartesian coordinate system)
What is Cartesian Dualism?
• Mind and body are separate things – Body • Corporeal – stuff of matter – Occupies space in the world • Mechanistic, predictable – Mind • Non-corporal – stuff of ether – Does not occupy space in the world • Location of spirit, soul, free will; not mechanistic;
What is the Cartesian reflex?
• Involuntary • Environmental energy moves pineal gland • Movement of gland opens valves • Nerve fluid flows • Muscles contract • No mind required – Automatic – Mechanistic
Cartesian voluntary action
• Information is carried from the world to the brain
– The perception part (meat)
• The mind/soul examines information in the brain and decides what to do
– Watches the show in the Cartesian “Theatre of the Mind”
– The “interpreter” in Morpheus’s description
• Mind/soul animates body by pushing the pineal gland around like a joystick, allowing fluid to flow, initiating action
– The action part (meat again)
• Perhaps intuitive but not scientific
– Can’t investigate things not part of the physical world
What introspective?
– “Look inside”
– Think about how you think
– Completely subjective
What is behaviorism?
– Everything we are and do reflects learned associations between stimuli or between stimuli and responses
– Measure input (stimuli) and output (responses)
– This is an experimental approach
What is cognitive/experimental psychology
Computational mental operations intervene between
stimulus and response
What is cognitive neuroscience (biological)
– Those computations reflect activity in the brain
What is our perspective
• Combination of cognitive, and cognitive neuroscience, relating experimental results with the biological bases of perception
– The mind is what the functioning brain produces, not a different thing separate from the body
• This is a monistic (one thing) perspective
– The phenomena of mind are what the brain generates when it functions
• Mind and brain are both aspects of the same thing
– All thought, feeling, and behavior comes from electrochemical brain activity and nowhere else
• There is no ‘ghost in the machine’
What is Psychophysics?
Experimental Methods Applied to Perception
– Manipulate the physical properties of the stimulus
– Query subject on their perception
• Relates individual’s mental experience (Psyche) with stimulus energy (Physics)
What is Fechner’s Law?
Fechner’s Law
• We become less sensitive to change in stimuli as the stimuli become more intense
– Our perception of the stimulus intensity grows slower than the actual stimulus intensity
– The function relating stimulus intensity to perceptual sensitivity is a logarithmic curve
Who coined the term Psychophysics?
Gustav Fechner
What are some examples of Psychophysiology?
– Method of Constant Stimuli
– Method of Limits
– Method of Adjustment
– Method of Magnitude Estimation
What is the Method of Constant Stimuli?
• Randomly present many stimuli of varying intensities
• Find the least intense stimulus the participant can detect
– Absolute threshold
• The threshold is not a firm value that you never perceive
below and always perceive above, but is surrounded by an ‘ambiguous zone’
– Near threshold, sometimes get them, sometime miss
– The 50% accuracy point is defined as the perceptual threshold
What is the Method of Limits?
• Stimuli aren’t presented randomly
– Constantly increasing then decreasing
• Find point where subject and first detect (increasing) or can no longer detect (decreasing) stimuli
– Average across runs to correct for overshoot
• Note that subjects usually report lower intensity stimuli when decreasing than increasing
– If you’ve been saying “yes” you’re more likely to keep saying “yes”
– An example of a response bias
What is the Method of Adjustment?
Same as Method of Limits except participant adjusts stimulus level until they can just perceive it
What is Magnitude Estimation?
• Present stimuli of varying intensities
• Ask participants to assign an intensity rating of their own choosing to each stimulus
– Could be number; could be comparison
– Must be internally consistent
What is JND and who developed it?
Just Noticeable Difference developed by Ernst Weber.
What is JND?
• How small can the difference be between two weights to have them judged different?
• How close together on the skin can two points be and still be perceived as two stimuli?
– Two point threshold
Who discovered that the relationships between physics and psychology was lawful?
Gustav Fechner
What laws describe Psychophysics mathematically?
Weber’s Law and Fechner’s Law
What is Weber’s Law?
• For weights
– 1/40 = .4
– 10/400 = .4
– 100/4000 = .4
Is JND for weights always a constant proportion for the over all weight? (Y/N)
Yes, because fuck you
We become more sensitive to change in stimuli as the stimuli becomes less intense. (T/F)
False. We become LESS sensitive to change in stimuli as the stimuli becomes MORE intense.
Our perception of the stimulus grows faster than the stimulus intensity. (T/F)
False. Our perception of the stimulus grows SLOWER than the stimulus intensity.
Stevens’ Power Law
• Using Magnitude Estimation, Stevens found that some perceptions didn’t follow Fechner’s law
– e.g. we become MORE sensitive to electric shock as the intensity increases
• Stevens generalized Fechner’s law for any kind of exponential function
– Not just the logarithm special case of exponential function
What is so special about Fechner’s Law?
• Fechner’s law showed for the first time that the mind followed lawful relationships too, and thus could be predicted
– You could test someone on several trial weights, find out how sensitive they were at those weights, then mathematically predict how sensitive they’d be to some weight they’d never experienced before
• Because the mind follows lawful rules and we know the rule
What is response biases?
– Different people may respond differently and the same person can respond differently at different times depending on all sorts of factors
• e.g. they may really not want to miss any stimuli so they respond even when they’re not sure they perceived something, just to be sure
• Or they may want to be sure they never make any wrong responses so they don’t respond even when they’re pretty sure they did perceive something, leading to the opposite bias
Are our neurons always firing?
Neurons are always firing whether there’s a stimulus there or not – how do we know that they’re firing because there’s something there?
What Perceptual Sensitivity?
• Our ability to distinguish signal+noise from noise alone is our perceptual sensitivity
– Called d’ (“dee prime”)
• The better we can distinguish signal+noise from noise, the higher our d’
What is Response Criterion?
• We set some level of perceptual certainty (how sure we are there’s a signal in there) as our response criterion
– Above that level of perceptual certainty, we respond “Yes: signal present”
• “signal present” = “target”
– Below we say “no: no signal, just noise”
• “no signal” = “rejection”
What are the 4 types of responses?
2 correct, 2 incorrect
You can do something about your sensitivity but you can’t change your response criterion. (T/F)
False. You CAN’T do anything about your sensitivity but you CAN change your response criterion.
How can you change the proportion of missed targets to false alarms for the same perceptual sensitivity?
By changing the confidence level required for a response you change the proportion.
What is the sensory transducer?
• Transforms environmental stimulus to electrochemical activity in the brain
Separate Parts of the Brain Perform Different Perceptual Computations. What are the separate parts of the brain?
Vision Audition Somatosensation Taste Smell
What are parts of the brain for vision in perceptual computations?
Primary = Occiptal Higher = Temporal, Parietal
What are parts of the brain for audition in perceptual computations?
Temporal
What are parts of the brain for somatosensation in perceptual computations?
Parietal
What are parts of the brain for taste in perceptual computations?
Parietal and Insular
What are parts of the brain for smell in perceptual computations?
Orbitofrontal
What is Neuroanatomy?
The structure of the Nervous System
What is the Hierarchic structure of the nervous system
• CNS =
– Brain
– Spine
• PNS =
– Somatic
• External world
– Touch
– Temperature/pain
– Autonomic
• Internal body
• Sympathetic
– arouse
• Parasympathetic
– RelaxWhat is system I/O?
It is the different nervous systems methods of input and output.
What is input?
• Input (sensory) – Afferent nerves • Brings information to the CNS from the periphery • "arrive" • Perception
What is output?
• Output (motor) – Efferent nerves • Takes commands out from the CNS to the periphery • "exit" • Action
Information enters and exits the CNS via __# of spinal and __# of cranial nerves (bundles of fibers which carry information – think cable)
30 spinal, 12 cranial
What is the purpose of Spinal Nerves? What do they do?
• Somatosensation • Each of the spinal nerves serves one part of the body – A dermatome • Spinal nerves are 'mixed' – Carry both sensory and motor signals
What is the purpose of Cranial Nerves? What do they do?
• Facial somatosensation and the other four senses
– Some sensory
– Some motor
– Some mixed
The Nervous System starts as a hollow tube. (T/F)
True. A developing fetus’s nervous system starts out as a hollow tube.
What do the 3 swellings the hollow tube of the nervous system develop into?
– Forebrain
– Midbrain
– Hindbrain
What happens to the rest of the hollow tube of a developing fetus after the 3 swellings have developed?
The rest becomes the spine.
What is found inside the spine of a developing fetus?
Cerebro-spinal fluid
– Ventricles
– Aqueducts
What Brain structures make up the Hindbrain?
• Medulla oblongata – Respiration, muscle tone • Cerebellum – Smooth motor action – Timing? – Learning? • Pons – Sleep and arousal • Reticular Formation – In both hind and midbrain
What Brain structures make up the Midbrain
• Tectum (roof) – Superior colliculus • Visual orienting – Inferior colliculus • Auditory orienting • Tegmentum (floor) – More reticular formation • Arousal – Periaqueductal gray • Pain regulation – Red nucleus • Motor – Substantia Nigra • Motor
What Brain structure makes up the Forebrain: Diencephalon?
• Thalamus – Contains sensory relay nuclei (among other things) • Hypothalamus – Homeostasis – Hormone regulation – Control of species-typical behaviors • The "four 'F's
What does the Basal Ganglia (Forebrain) regulate?
• Motor regulation – Projections to Basal Ganglia from Substantia Nigra damaged in Parkinson’s • Reward motivation • Other cognitive functions • Memory, attention • Not well understood
What does the Limbic System (Forebrain) handle?
- Emotions
* Memory
What does the Neocortex (Forebrain) manage?
• Gray matter – Neuron cell bodies • White matter – Fiber tracts (axons) • Gyri – Humps • Sulci – Valleys • Fissures – Big valleys
What are Neurons?
The brain’s computational and signaling units
What is the Basic Neuron Structure?
• Soma (cell body) – Metabolic center • Dendrites – Primary input to cell • Axon – Output pathway (nerves are bundles of axons) • Single output from soma • Multiple terminal branches (sometimes thousands) • Myelin sheath – Insulates axon • Terminal buttons – Output terminal
What are the 3 general types of neurons
Unipolar, Bipolar, Multipolar
What do Unipolar neurons do?
– One process from cell body
– Sensory, primarily touch and pain
What do Bipolar neurons do?
– Two processes
– Primarily sensory transduction
What do Multipolar neurons do?
– Multiple processes
– Many different configurations
– Ubiquitous in nervous system
Do Neurons connect with each other at synapses? (Y/N)
Yes
What are the 4 synapses neurons can connect with each with called?
Axo-dendritic
Axo-somatic
Axo-axonic
Dendro-dendritic
List in order the most common type of synapse to neuron connectors from most common to rarest.
Axo-dendritic - Most common
Axo-somatic - Common
Axo-axonic - Important for learning
Dendro-dendritic - Rare
The “skin” of a neuron does not have holes in it. (T/F)
False they do have holes in their “skin”
