Module 4 Flashcards
Sensation
Conversion of physical properties of the world or body into a neural code by the peripheral nervous system
Transduction
Process of converting physical properties into a neural code
Perception
Processing and interpretation of the sensory information to be used for a behavioral decision
Exteroception
Sensing and processing of information from the external environment by the 5 basic senses: vision, audition, touch, taste, and smell.
Interoception
Sensing and processing of information from inside the body
Proprioception
Perception of our body in space
Nociception
Sense of pain due to body damage
Equilibrioception
Sense of balance
Chemoreceptors
Sensory receptors with nerve endings that respond to chemicals in the environment
Mechanoreceptors
Sensory receptors that respond to mechanical force
Thermoreceptors
Sensory receptors that respond to heat
Photoreceptors
Sensory receptors that respond to light
Synesthesia
- A neurological condition in which one sense automatically triggers the experience of another sense
- More common in women, genetic and stable pairings in time
Grapheme-colour synesthesia
Colour with letter/numbers (e.g. 2 is yellow)
Chromesthesia
Sound evokes color
Synesthesia stimulates ______
Creativity
Synesthesia is due to cross-talk between ______ regions for different senses
Processing
McGurk effect
A voice articulating a consonant (/ba/) paired with a face articulating another one (/fa/) leads you to “hear” what you “see” (hear /fa/); shows dominance of visual input
3 steps of sensory processes
1) transduction of physical energy into a neural code by the senses
2) transmission to the brain through subcortical and then cortical structures,
3) processing in the cortex to generate behavior
Cornea
Transparent layer of tissue in front of the eyeball that bends light to focus it on the retina
Iris
Ring of colored muscle around the pupil that contracts or relaxes in order to determine the size of the pupil
Pupil
Small hole at the center of the iris that controls how much light gets in the eye
Pathway of light
- Cornea
- Pupil
- Lens
Focus
A property of an image in which specific locations in the environment correspond to specific locations on the imaging device.
Light from above falls on the ____bottom/top of the retina
Bottom
Far objects produce a _____smaller/bigger image on the retina
Smaller
Structure of the eye responsible for the switch in light direction when it enters the eye
Pupil
Retina
Structure in the back of the eye made of layers of neurons, forms an inverted image (because front curved part of the eye will bend the light)
Photoreceptors
Sensory receptors in the last layer of the retina that respond to light.
Neurons that transduce light into neural signals
Photoreceptors
Rod
A type of photoreceptor in the retina, outside of central vision, that responds to lower light but with reduced spatial acuity and no color differentiation.
Cone
A type of photoreceptor, largely contained in the central fovea of the retina, that supports high spatial resolution and color vision under higher lighting conditions.
Fovea
A depression in the center of the retina that is densely packed with cone photoreceptors and is responsible for seeing detailed properties.
Early visual processing steps
- Light waves enter the eye
- Retina photoreceptors convert light to electrical activity
- The electrical signal is sent to bipolar cells, then sent on to the ganglion cells
- The signal exits through the optic nerve to the brain for later visual processing
Compression of information in the retina
Millions of photoreceptors in each retina converge onto 100 x fewer ganglion cells → optic nerve → brain
Input from the eyes to the brain is compressed
Perceptual filling in
Later visual processes will fill in some of the less detailed visual periphery with what is in the center; also fill in the blind spot
Blind spot
Ganglion cells make up the optic nerve that exits the eye (passing through the photoreceptors leaving a hole ) to the brain. At this ‘exit location’, there are no photoreceptors
Thalamus
Subcortical region of the brain that serves as something of a way-station between sensory inputs and the cortex.
Primary visual cortex V1
First region of the cortex to receive visual input. Unconscious vision
Visual signal is broken down into :
* Edges
* Angles
* Color
* Light
Visual association areas
Interpret visual signal, assigns meaning to it, allows to see what and where ( the what and the where pathways).
Agnosia
Difficulty recognizing or perceiving one kind of visual stimulus
Prosopagnosia
Difficulty recognizing individual faces due to FFA (fusiform face area) damagre
Semantic agnosia
Difficulty recognizing objects
Fusiform face area (FFA)
Region of the inferior temporal cortex that shows greater activity when people engage in a facial recognition task
Lateral occipital cortex (LOC)
Selectively activated when people do an object recognition task
Can the fusiform face area only process faces according to the greebles research?
No, also objects (linked to more
expertise of recognition)
The dorsal stream projects upward and terminates in the _____ lobe
Parietal
The ventral stream projects downward and terminates in the _____ lobe.
Temporal
The what pathway
Ventral stream, from occipital to temporal lobes
* Shape, size, visual details : recognize the object
The where pathway
Dorsal stream, upper occipital to parietal lobes
* Location, space, movement information
In the cortex, visual input is broken down, processed separately and then _______
Combined
According to Goodale and Milner’s theory, the ventral stream is linked to _____perception/action
Perception
According to Goodale and Milner’s theory, the dorsal stream is linked to _____perception/action
Action
Olfaction
Sense of smell
Gustation
Sense of taste
Taste buds
Structures on the surface of the tongue that contain the sensory receptors for taste.
On tongue, palate, pharynx, upper esophagus
Lateral sulcus
A deep fissure that divides both the frontal and parietal lobes form the temporal lobe, part of the primary gustatory cortex
Primary gustatory cortex
The first region of the cortex to receive information from the gustatory sensory system.
Olfactory epithelium
Strip of tissue in the nasal cavity that contains tens of millions of chemical sensory receptors that transduce odors before sending them to the brain
Specialized brain structure that sits at the bottom of the forebrain that receives information from the olfactory epithelium
Olfacotry bulb
The olfactory bulb projects to several other brain structures including the _____ , which is involved in emotional processing, and the _____, which is involved in memory formation.
Amygdala, hippocampus
Somatosensory cortex
Region of the brain, located in the parietal lobe, that receives multiple sources of sensory information from across the body, including sensation of touch.
Cortical homunculus
A spatially organized map of the human body, contained within the somatosensory cortex, that processes touch information.
Constructive perception
A model of perception in which the sensory information is used to generate a mental model of the environment that is assumed to have caused the sensory stimulus.
Direct perception
A theoretical approach to perception that holds that the sensory stimuli be used to guide behavior in an action/perception loop.
Lightness
Perception of how dark or light a surface is
Bi-stable
Property of a stimulus that has alternating stable perceptual interpretations.
Bottom-up processing
Perceptual processing that is applied generally to all stimuli and does not depend on specific knowledge of the stimulus or its category.
Top-down processing
Perceptual processing that leverages prior stimulus or category specific knowledge to interpret new information
Phonemic restoration effect
A perceptual phenomenon in which missing sounds are “filled in” by the brain based on knowledge of language.
Figure-ground assignment
The determination of which side of a boundary contains the shape versus the background.
Visual grouping
The perception of discrete visual elements as forming a larger pattern or whole.
The tendency to group together features of the image that have similar properties in some dimension
Law of similarity
The tendency to group features of the image that are close together
Law of proximity
The law of good continuation/contour
Tendency to group together features that form a smooth, continuous path rather than those with a sharp discontinuity.
Motion parallax
A cue to depth perception based on the fact that, when moving, objects that are closer to you change their position in the visual field more quickly than those that are further away.
Binocular disparity
The image of the world falling on each eye is different
Stereopsis
The use of binocular disparity (the fact that image falling in the two eyes is different) in perceiving depth.
Template
A simple model of recognition that depends on directly matching an incoming image to an image of an object or category in order to determine whether they reach some threshold of similarity.
A form of recognition that consists of determining whether a given image corresponds to a specific individual object or individual.
Identification
A form of recognition that consists of determining whether a given image corresponds to a class or category.
Classification
General recognition
The ability for a computer to classify a broad class of different objects.
A learned representation of which objects tend to appear in specific kinds of scenes.
Scene schema
Pinna
Visible portion of ear made up of folded cartilage; gathers and transmits sound into the ear canal. Its shape allows to direct sound into the ear canal, and amplifies sound frequencies.
A thin piece of tissue separating the ear canal from the inner ear that amplifies certain frequencies and passes them to a series of tiny bones called the ossicles.
Eardrum
A narrow tube following from the pinna that amplifies certain sound frequencies and transmits them to the eardrum.
Ear canal
Ossicles
Set of three tiny bones in the inner ear that amplifies certain frequencies and relays them to the cochlea. Order : hammer, anvil, stapes
Ostosclerosis
Hardening of the ossicles that prevent them from sending information to the cochlea
Cochlea
Coiled, bony structure in the inner ear that is filled with fluid and contains the basilar membrane. Sound vibrations become fluid vibrations that travel as a wave through the cochlea.
A strip of tissue inside the cochlea that contains the hair cells that transduce sound. It is more thick at the start (high frequency) and thinner at the back (smaller frequency)
Basilar membrane
A type of mechanoreceptor situated in the basilar membrane that are stimulated by vibrations in the fluid in the cochlea, which they convert into a neural signal that is sent to the brain.
Hair cells
Afferent auditory nerve
Goes to the brain
Efferent auditory nerve
From brain to hair cell nucleus
Tonotopic map
A spatial arrangement of neural structures (such as hair cells) in which locations are organized based on the frequency of sound they encode.
The further along the cochlea coil, the ___lower/higher the frequencies
Lower
A region in the temporal lobe of the cortex that is the first to receive auditory information from the auditory nerve in the cortex .
primary auditory cortex (A1)
Dorsal pathway of sound
Sound localisation
Ventral pathway of sound
Sound properties
Other ways animals can hear
- Snakes pick up vibrations of the earth by their jawbone
- Mantises detect vibrations in a groove on their thorax
Vinyl functioning
Cartridge reads stylus vibrations and read the signal to send it to the listener as an electrical signal
_____Lower/higher pitches are perceived as louder
Higher
Loudness is the perception correlate of the physical ___ (amplitude)
Pitch
To hear a low frequency at the same volume as the same sound with a higher frequency, you need to ______decrease/increase volume
Increase
2 cues for perceiving location of sounds
Interaural time difference (ITD) : closer ear has burst of energy a bit earlier than the other ear (tiny difference, but the brain can capture it)
Interaural level difference (ILD) : sound is more intense on one side
Pinna : vertical cues
Gestalt law of similarity for auditory perception
- 2 similar melodies = hard to distinguish them
- Different pitch = can identify the other melody : the brain can segregate between the melodies
Grouping by proximity (Temporal, sequential integration)
A: Slowly interleaved high and low tones create a single sequence with shifting pitch ranges.
B: Quickly interleaved tones form two simultaneous streams, one high-pitched and one low-pitched.
Connectedness law
A: Unconnected high and low tones form separate streams
B: Connected high and low tones create a single, undulating auditory strea
Active Noise Cancelling reduces noise by emitting an antiphase sound wave of equal ______, canceling
unwanted sound through interference.
Amplitude
Fundamental frequency:
Lowest frequency component (less Hz)
Harmonics
Multiples of the fundamental frequency
The way the _____ shift is what allows us to distinguish between 2 sounds with the same amplitude and frequency
Harmonics
Interpersonal sync
Sync is a biological mechanism that aligns behaviors ( - Neural sync when watching video clips and listening to live music
- Behavioral sync occurs even without the intention
- Cardiac and respiratory sync in choir singing)
_____ connection during painful stimuli caused more syncing
Physical
Children show more _____ behavior after interpersonal synchronous movement
Prosocial
Three key characteristics of sound waves
Loudness (amplitude), pitch (frequency), and
quality (complexity)
______ of sounds is a computational challenge solved through Gestalt principles like
similarity, proximity, and connectedness.
Superposition
Oscillating movement in the air caused by vibrations of objects in the environment.
Sound waves
Frequency
Lengths of a wave defined as the distance between the crests of sequential waves.
The length from the trough of a wave to its crest.
Amplitude
Low frequency means something moves ____slower/faster and is likely ____smaller/larger
Slower, larger
High frequency means ___low/high pitch
High
More powerful vibration and loudness means ____less/more amplitude
More
As waves propagate away from their original source, their frequency _____decreases/increases and their amplitude ________decreases/increases.
Frequency increases and amplitude decreases
Sound
Vibration that travels as a pressure wave of high and low pressure
Sound waves _____ and ______ air molecules
Compress and expand
Vibration is a periodic motion around a ____ point
Stable
When waves go up, there is _____compression/refraction
Compression
When waves go down, there is _____compression/refraction
Rarefaction
The propagation of _____ (oscillation around a single point) through air enables hearing
Motion (not travelling molecules)
The compression phase ______decreases/increases air pressure, while rarefaction _____ it
Compression : increase
Rarefaction : decrease
Pressure waves can travel through different mediums, but ____ differs across mediums
Speed
Bottom up processing
- Information from the sensory organs (eyes) to the visual cortex
-the influence of information from the external environment on perception
Top down processing
- The influence of knowledge (expectations, context and goals) on perception
- Information from higher processing brain regions (prefrontal cortex or higher visual processing areas) is sent back to the sensory organs
Constructivist theory of perception
Top-down processes influence bottom-up processes
* We use what we know and expect to interpret sensory information, construct our reality
Ponzo illusion
Something converging at the top : brain uses cues to assume what is there is larger (depth)
Color perception depends on :
- The wavelengths of light that fall on our retina
- Our expectation (from experience) of how objects look under contexts of illumination
Approach motivation effect
Desirable objects appear closer, larger than less desirable objects
When focused, you are less likely to take in ____
Details (opposite when bored)
Touch information pathway
Mechanoreceptors (in the skin) →spine → somatosensory cortex
Only sense that does not go to the thalamus relay station
Olfaction
Sense of smell is related to brain integrity as we age and early symptom of ______
Demantia
Why do taste signals get projected to the reward PFC area ?
It helps us know what is bad for us to eat (what is not rewarding)
Red is linked to ____ taste
Sweet
Green is linked to ____ taste
Bitter
Mental models in top down perception
- Mental models include sensory inputs, but also inferences, assumptions and understanding of the world (top down, what is already in our mind, can be unconscious); They are what we use to guide our behavior
3 steps of top down perception
- Sensory input
- Mental model
- Perception and action
True or false : bottom up processes are always unvoluntary
False, for example goals can influence them
How does the visual pathway show interaction between top down and bottom up processing ?
Information from final stages of visual pathway processing is sent back to the visual cortex
Top down visual assumptions
- The Ponzo illusion : depth assumption
- The monster illusion : depth assumption
- The world is lit from above : how and what we see in an image depends upon our implicit understanding of shadows
Auditory illusions (auditory bistable figures) :
Changing expectations can change our perception : hearing a different word based on the word you read while the sound does not change
Ambiguous bistable figures
Ambiguous visual figures that can be perceived as one of 2 objects : unclear what the figure is, and what is the background (cannot see both images at same time, but can switch between them)
Gestalt Psychology
Top down organizational principles to deal with ambiguous figures like bistable figures
Principle of closed forms
We see a shape in terms of closed forms, and we like to see items that enclosed as whole
When showed a bistable figure that looked either like a duck or a rabbit, children …
Children were more likely to see rabbits in easter, more likely to see ducks in October
Passive bottom up approach to perception (direct model)
Information form the environment does not need to be interpreted with our knowledge
Direct approaches require an _____ approach to understand perception –study it in the real world (JJ Gibson) because information from the sensory data is what guides perception, not what is going on in our mind
Ecological
Ambient optical array (AOA)
Visual signal from your current viewpoint that reaches the retina
According to direct models, passive cues to perception are not in the mind bu in the …
Ambient optical array (AOA)
Topographical breakages cue in AOA
Discontinuity helps see edges and define objects
Scatter reflection cue in AOA
How widely light scatters off an object’s surface provides cues about the nature of the surface (what it is made of), if light scatters widely : rough surface
Texture gradients cues in AOA
Incremental changes in texture can provide information about your movement and distance (far pattern = closer together objects )
Affordances
Cues that indicate potential function of an object, how to interact with it (visual cues like texture, size, distance)
For constructivists : use from experience and learning
For direct models : use from implicit computing
Blindsight
No conscious awareness (explicit perception) of visual objects in damaged visual field (where primary visual cortex is damaged); but can still answer implicitly when asked about what is in the damaged visual field
Scotoma
Blinded visual field
Test for blindsight perception
Patients performed above chance on the forced-choice responding task for lights in the blinded area
There may be other pathways for visual information to bypass the ____ (detour)
Primary visual cortex
True or false : the what and where pathways are part of conscious vision
True
Akinetopsia
Damage to the dorsal where pathwa causing visual motion blindness (perceive motion as series of stationary objects)
Optic ataxia
Symptom of akinetopsia causing an inability reaching or pointing for objects(can be selective for certain types of movements)
Visual agnosia
Difficulty recognizing objects from damage to lateral occipital cortex (can be specific to visual category, e.g. face)
Auditory agnosia
Difficulty identifying objects through sounds
Olfactory agnosia
Difficulty recognizing smells
Evidence against FFA specialization
- fMRI data as participants viewed “greebles” and other objects
- Greebles activated FFA more than other objects (cats, household objects)
- Maybe FFA just linked to visual expertise
Sheep farmer with prosopagnosia
- Can recognize and discriminate sheep (expertise) with very high accuracy (~90%) vs failure at face recognition; opposite of greebles study finding : selective human face processing in the brain
Associative agnosia
Problems assigning meaning to objects (for prosopagnosia, can’t recognize familiar famous faces; can still copy drawings
Apperceptive visual agnosia
- A failure to recognize objects and facial expressions due to problems with perceiving the elements of the objects as a whole
- Single visual feature perception (e.g., color, motion) are relatively intact
Pattern recognition
Perception involves processing basic visual features. Pattern recognition suggests we then add up these features and match it to existing patterns (concepts) stored in memory
Feature detection
- Visual input is broken down into individual parts (features)
- Each feature is processed separately
Probe
Combination of features that is matched to long-term memory traces, looking for a match
* The highest similarity between the probe and memory trace will
determine recognition
Template (exemplar) matching theory
Every object has a ‘template’ in long-term memory
Problems with template matching theory
Cannot explain
* Identification: The ability to recognize objects with shifts in perspective
* Classification: The ability to recognize new objects as members of a known category (ex. recognize new bird as a bird even without a matching template)
Prototype theory
- A prototype is the average representation of an object concept
- recognition is determined not by literal match, but to a prototype
- A ‘good enough’ match (resemblance) leads to identification
Scene constitency effect
Ability to name an object is faster in a consistent context
Impact of inconsistent scene and object
Semantic violation signal in the brain
