Lecture 4/5: Perception

Question 1

Extroceptive sensations

Answer 1

• Any form of sensation that results from stimuli located outside the body detected by sensory organs
• Sensations that occur in our sensory organs. Your eyes, ear, nose, taste budss.
• Your sensory organs will absorb energy from a physical stimuli in the environment (light, vibrations, chemical compounds). The sensory organs have receptors that absorb this energy and then convert it.
• Sensations from the exterior world that we take in

Question 2

Interoceptive sensations

Answer 2

Sensations from inside our body (source of what you are sensing comes from inside your body).
Examples of this:
* Proprioception: Sense of where our limbs are in space (good sense of where your limbs are in space)
* Nociception: Sense of pain due to body damage (sensation of pain)
* Equilibrioception: Sense of balance
* Dancers have increased interoceptive accuracy (Christensen et al., 2017). They are able to sense their heart rate (estimate their heart rate at different moments and then saw how far they were from actual heart rate).
* They could estimate heart rate more accurately than non-dancers
* This was unrelated to fitness levels or counting ability

Question 3

Synaesthesia

Answer 3

Senses can mix: Synaesthesia
* A neurological condition in which one sense automatically triggers the experience of another sense. They perceive two senses, just by the trigerring of one.

Grapheme-color synesthesia
* A person sees colors with certain letters or numbers. They see letters and numbers with colours (ex: 5 are always in green and 2s are always in red.
* Most popular one

• Genetic component (abou 40% of synaesthesed have a family member with it)
• One hypothesis is that it is due to cross wiring (cross-talk) between processing areas in the brain. For example, the area of the brain that is involved in processing language stimuli and colour sit next to each other in the brain. It could be that for some reason there is some overlap there.
• Weird example: individual sensed time with a hoolahoop around her body (time and bodily)
• see something and automatically hear music.

Question 4

Synesthesia is very popular in artists

Answer 4

• Artists are eight times more likely to have synesthesia than nonartists. Ex: pharell williams, stevie wonder, billie eillish (every person i know has their own color and shape and number in my head).
• One explanation is that maybe it is something that can be beneficial.
• The cross-talk between sensory areas in the brain increases the ability to think creatively and in metaphors

Question 5

Sensations and Perceptions

Answer 5

• How do sensations merge to become something that you perceive? For all modalaties, we have this general process to get from sensation to perception.
• Stimuli is registered by a sensory receptor.
• Transduction of physical energy into a neural impulse (code).
• This code is translated into the brain through subcortical regions and then the cortex to generate behaviour and perception.
• Perception is when the brain is translating those impulses into something meaninful.

Question 6

Sensation or Perception?
Touch
Smell
Bright color
Pleasant sounds
Body position
Pain

Answer 6

Touch - S
Smell - S
Bright color - P
Pleasant sounds - P
Body position - S
Pain - P

Question 7

Vision

Answer 7

• Most well researched and most dominant form of perception in our world.

Question 8

McGurk Effect

Answer 8

McGurk Effect: When you hear what you see
* A multisensory illusion such that there is a change in auditory perception from visual perception
* A voice articulating a consonant (/ba/) paired with a face articulating another one (/fa/) leads you to “hear” what you
“see”
* This shows us that there is an integration of sensory information. Shows that we integrate information across our senses. Other processes can affect what we can perceive.
* Question to think about: Can you experience sensory modalities separately?
* This also illustrates the dominance of visual input. The Mcgurk effect shows the power and importance of visual input.

Question 9

The visual system

Answer 9

• Early visual processing (rhelm ofsensation)
  → supported by our Eyes and the optic nerve
• Late visual processing (perception)
  → supported by The visual cortex (occipital lobe)

Question 10

Early visual processing

Answer 10

1) Vision begins with out eyes. Light waves enter the eye, the light waves are then focused and inverted by the cornea and are projected onto the retina
* The retina, a thin layer of tissue at the back of the eye, forms an inverted image.
* Image is inverted because the front part of the eye is curved so it bends light.
* Later processes turn this image around

Retina has 3 types of receptive neurons in it: photoreceptors, bipolar cells and ganglion cellss.

2) Photoreceptors in the retina convert light to electrical activity.
Two types of photoreceptors:
* Rods: processing low light levels for night vision (light sensitive)
* Cones: processing high light levels for detailed color vision

3) The electrical signal is sent to bipolar cells and then to the ganglion cells.

4) The signal exits through the optic nerve to the brain

Question 11

Information compression (phenomena that occurs in early stages)

Answer 11

• Information is compressed quite a lot in your early visual system.
• You have about 125 Million of photoreceptors in each retina that converge onto 100 x fewer ganglion cells → optic nerve → brain
• Input from the eyes to the brain is compressed. Your vision in that process is compressed 100times, we are not having a 1 to 1 correspondance.
• You don’t ‘see’ everything that is out there in the world

Question 12

Photoreceptors distribution in the retina

Answer 12

Photoreceptors aren’t equally distributed in the retina → cells in the retina are set up in a non uniform way
* Cones (pick up high level of light, detail) are most concentrated in the fovea, which is a small area on the the central part of the visual field
* Center of your visual field is most detailed. Information in the center of your visual field is the most accurate or detailed.
* Rods (don’t pick up a lot of light) are mostly outside of the fovea, in the periphery
* Periphery of your visual field is less detailed and less accurate (more rods then).

Question 13

Perceptual filling-in

Answer 13

• Visual processing systems will fill in what your periphery should see/should be perceiving.
• You are filling in the outside of the image with details that you see in the center.

Question 14

Blindspot

Answer 14

• Photoreceptors are at the back of the retina (farther from the ‘world’)
• Ganglion cells are at the front of the retina (closer to the ‘world’)
• Ganglion cells make up the optic nerve that take this signal to the brain and have move past the photoreceptor layer
• At this ‘exit location’, there are no photoreceptors so visual stimuli are not received

Axons of the ganglia make up the optic nerve. The optic nerve has to pass through the photoreceptors to exit. So there will be a spot with no photoreceptors. No photoreceptors = you cannnot take in light = don’t see anything.

Question 15

Why do we not see our blind spot??

Answer 15

But we do not ‘see’ our blindspot!
* This is because of perceptual filling-in. Visual systems will take information around your blind spot and fill it in.
* Later visual processes in the brain provide the missing information by ‘interpolating’ visual information (e.g., colors) from surrounding areas
* This is also because the left and right visual fields can compensate for each other’s blindspot. Due to the way that information travels from the early to late visual sytem. The optic chiasm is what allows your left and right field to fill in the blind spot

Question 16

Early to late visual processing

Answer 16

Perceptual filling in requires the late visual processing.
* For the information from the early system to be received by the late processing, it has to exit the eye through the optic nerve and then hit the thalamus (subcortical structure - deep within the brain) and tthen there is a transfer of information between sensory, the optic nerve and information to the cortex.
* Thalamus: A way-station between sensory inputs and the cortex
* The optic nerve of each eye transmits information to both hemispheres, leading to the principle of contralateral representation. Some of the axons from the right or left side will swtich sides. Each optic nerve does transmit a signal to each hemisphere.
Contralateral:
* Left visual field is perceived via the right hemisphere
* Right visual field is perceived via the left hemisphere
* This is what allows your left and right visual field to fill in the blinspot.

Question 17

Late visual processing

Answer 17

*Late visual processing occurs in the occipital lobe.
* Primary visual cortex - area is responsible for the late processing of the visual system.
* Some of the most basic processing in the late visual system goees from very simple feature based processing all up to something that is more integraded and complex.

1) Primary Visual Cortex contains specialized regions that process particular visual attributes or features (functional specialization).

Differerent types of cells process different kinds of visual information. They will process different types of attributes:
* Edges
* Angles
* Color
* Light

• For each aspect of the signal that reflects these more simple features, they are going to be processed in different parts of the primary visual cortex. It does happen in parallel, which means it happen at the same time.
• Whatever you are seing is broken down and processed seperatly in the primary visual cortex.

2) Visual Association Areas interpret visual information and assigns meaning
- information from the primary visual cortex is projected to the visual association area. At this point, we start assigning meaning to what we see
- What and where pathways
- what pathways: visual object recognition
- where pathway: object location

Question 18

Pathways to the visual association areas

Answer 18

What (ventral) pathway:
* Occipital to temporal lobes
* Shape, size, visual details
Where (dorsal) pathway
* Occipital to parietal lobes
* Location, space, movement information

• Neuroimaging studies show separation of what and where pathways. You see seperate activity along the what and where pathway.

Question 19

Neuropsychological case of dorsal
‘where’ pathway

Answer 19

Ventral damage with intact dorsal stream
* Impaired performance on visual object recognition or matching tasks (cannot match the cat to the image visually).
* Can usually recognize other obkects with other sensory modalities (touch, smell)

Dorsal damage with intact ventral stream
* Accurate performance on object recognition or matching tasks
* Impaired performance on visual guided action (picking up an object appropriately). Cannot do any task that requires space or motion. Cannot locate an object in space. Bad grasping.

• Some suggest this may mean that dorsal and ventral pathway represent “perception” and “action”

Question 20

Lessons from the visual system

Answer 20

• Visual stimuli is altered at many stages of the
  processing pipeline (e.g., inversion, compression,
  within the primary visual cortex). You do not perceive stimuli directly
• In the cortex, visual input is broken down, processed
  separately and then combined to form a perception of
  an entity
• The reality we perceive is a construction of the brain

Question 21

Bottom-up vs Top-down processing

Answer 21

• Bottom-up processing: the influence of information from the external environment on perception
• Information from the sensory organs (eyes) to the visual cortex. Vision: input from eyes to brain (represents bottom up processing). What we see is influencing what we are processing. “Signal is on the ground”
• Top-down processing: the influence of knowledge (expectations, context and goals) on perception
• Information from final stages of higher areas of the brain (prefrontal cortex or higher visual processing areas) that is sent back to the visual cortex
• Information from your mind is influencing the processing. Information processed in these higher regions of the brain will send a signal back down to the visual cortex.

Question 22

Ambiguity in what we perceive

Answer 22

Constructivist Theory of Perception: Top down processes can influence data.
* Governed by top-down processes
* We use what we know, and current context to predict how to perceive sensory data. Sensory input can be interpreted in a variety of ways. There is ambiguity in sensory data due to top down processing. Your braiin navigates your world and predicts things.
* your brain will use what it knows to guide perception and so forth. It is a predictive organ

Question 23

Pain perception is subjective

Answer 23

• Perception of pain is partly determined by expectation
• Rate pain of the shock in Phase 2 in the low and high cue trials. Sometimes the participants were given the shock with a queue (a shape) “when you see a shape, the shock that is coming next will be very painful” (high pain trial). Low pain trials “the shock coming will not be so bad”
• The shock levels were the same across conditions → regardless of the high or low pain trial, they gave the same shock (objectively no difference in shock)
• Pain ratings were higher in the high-cue than the low-cue. Expectation of pain changed their perception of it.

Question 24

The Ponzo illusion

Answer 24

Visual illusions show what assumptions you bring about what the world should look.
- you are bringing your assumptions about depth perception. or assumption about how light comes from above.

Question 25

Perception is predicted by what

Answer 25

Perception is predicted by knowledge * We use assumptions about what we expect to see to guide perception * Knowledge, heuristics and schemas that reflect assumptions about how the world works, affects perception * The specific illusions we are susceptible to illustrate some of these assumptions

Question 26

Contexts affects visual perception

Answer 26

* Changes in visual perception based on the surrounding information (the context). - top down processing - context you are in can shift what you see - how eople ask you something or what questions you see affects your perception. Three examples * Ames Room * Letter in Context * Color in Context

Question 27

Ames room

Answer 27

* A functional illusion when expectations guide perception * These are expectations of ‘observation’ * Room is constructed as trapezoid (walls are slandered) * Person will assume they are looking into a rectangle room not a trapezoid room.

Question 28

Context constructs perception: The letters in context effect

Answer 28

* The ability to read words in sentences even when the letters in the middle of some of the words are mixed up * This is because you ‘expect’ to see real words in a sentence * We perceive and read words as words even if the letters are mixed up. * When we see sentences, we are in context that assumes the words are correct. You can stlil raed this senetnece even thuogh lettres in the wrods are jubmled.

Question 29

Context construct perception: the color in context effect

Answer 29

The context a color appears in can influence how you see that color. * Color perception depends on both: * the wavelengths of light that fall on our retina * Our past experiences of how objects look under different contexts of illumination Context of a colour can shift your perception of it. Dark colour background makes inner square look like a different colour than the little square in little background.

Question 30

Review Sensations to Perception

Answer 30

* Sensation can be internal or external, it is registered then sent to the brain * Perception is something meaningful, it can change based on where we are, our motivations... * Different types of sensations * General process involves registering stimuli energy and transmitting it to the brain * Perception is when meaning is added t sensory data * Perceptions are subjective and can change * According to how you feel, desirable objects will appear closer/larger than less desirable objects * A water bottle appears closer than crackers when thirsty * Hills look steeper when you are tired

Question 31

The early visual system

Answer 31

* Light waves enter the eye through the cornea, focused onto the retina as an inverted image * Photoreceptors in the retina convert light to electrical activity. Retina contains rods and cones (cones are more concentrated in the fovea). Our vision is high resolution (detailed) in the center of the eye. * Electrical activity is sent to the bipolar cells then ganglion cells * This signal is sent to the brain via the optic nerve

Question 32

Late Visual system

Answer 32

* Optic nerve will send info to both hemispheres * The primary visual cortex (PVC) is the first stop in cortex for processing visual input * Demonstrates functional specialization - Features of visual input are processed in different regions * Damage leads to conscious vision loss - Demonstrates we can have perception without awareness

Question 33

Damage to the primary visual cortex

Answer 33

**Blindsight** * No conscious awareness (explicit perception) of visual objects in their damaged visual field. Not aware of anything in their damaged visual field. * Able to implicitly respond to questions about objects presented in the damaged visual field (if you present anything in this area, the person will say they can't see anything but if they guess they will be correct). * Suggests that they can perceive something without ‘consciousness’ or awareness (implicit perception). We can perceive without being consciously aware about it but it might still influence our behaviour and actions * There is a processing division between conscious (explicit) and non-conscious(implicit) perception.

Question 34

Test of blindsight (experiment)

Answer 34

* Over trials, turn a light on or off in the blinded visual field * Ask patients to guess if the light was on or off (forced choice responding task) * Patients performed above chance on the forced-choice responding task for lights in the blinded area

Question 35

Blindsight

Answer 35

* Perception is first processed without conscious awareness in the brain * Awareness and perception can dissociate. Awareness is not an all or none thing. * Raises the idea that awareness is on a continuum with respect to perception * Critiques - There may be other pathways for visual information to bypass the PVC (alternate pathway) - These cases rely on self report. Rely on subjective reports (people accessing information about their own consciousness) - Some blindsight cases report a non-visual feeling that something happened

Question 36

Blindsight and visual imagery (experiment)

Answer 36

Trial 1: Ask patients to look at images of houses and faces. Trial 2: Ask patients to imagine houses and faces Results: * people with blindsight didn't show activity in areas that are related to explicit visual perception. * Brains of patients looked more similar when they were imagining vs looking at images. * Activity of patient with blindsight perceiving faces and houses was reduced when compared to control participants * Activity of patient with blindsight when imagining faces and houses was similar to control participants * Blindsight leads to deficits in consciously processing incoming visual information but not imagery * There is something different between perceiving and imagining perceptions. Or, the blinsighted individuals have a selective deficit when they are processing information that has to travel from external world up visual processing pipeline to the higher association areas. For imagery, you do not need that pipeline. It comes from inside.

Question 37

Damage to the "where" pathway

Answer 37

Damage to the what and where pathways affects conscious perception * The dorsal ‘where’ pathway goes to the parietal lobe * spatial information * depth perception * estimating movement and direction of objects * problems with motion processing (akinetopias)

Question 38

Akinetopsia

Answer 38

* Damage to the dorsal where pathway * Visual motion blindness: cannot see motion. Instead, perceives motion as a series of stationary objects * Movement is just really a bunch of static snapshots for these individuals.

Question 39

Optic Ataxia

Answer 39

* Damage to the dorsal where pathway (this is why people have suggested that the where pathway is important for action) * Inability to reach for objects with the ability to name objects. Can still name the object, just can't reach out and grab it. - Problems reaching for a cup of coffee … can recognize coffee - Problems pouring milk … can recognize milk * There might be action specificity in this pathway - Selective damage leads to problems with certain types of movement. Damage to different regions in the brain within the where pathway will lead to specific action impairements (person only has problems for a certain type of movement: eye movement)

Question 40

Visual agnosia

Answer 40

* Damage to the ventral what pathway * Difficulties recognizing everyday objects. Cannot identify visual objects with visual sense but can with other senses. * Often from damage to the Lateral Occipital Cortex * Difficulties can be selective to visual categories (faces) - Functional specialization within the ventral pathway - Can get damage to different areas along the pathway that will lead to different visual agnosia

Question 41

Prosopagnosia

Answer 41

* Fusiform face area (FFA) damage leads to a selective deficit in recognizing faces, keeping intact the ability to visually recognize other objects * Rely on non facial characteristicss to recognize the person (clothing, hairstyle).

Question 42

What was the theory of people that did not believe in the functional specialization for faces?

Answer 42

* Is the FFA special for faces or just discrimination? * Participants learn to discriminate between “Greebles”. The ones that had learned to discriminate them had more activity in the FFA. * fMRI data as participants viewed greebles and other objects * Greebles activated FFA more than other objects (cats, household objects) * FFA is very important for face processing. There is some controversity - maybe it is just important for discriminating things that are similar.

Question 43

The case of the sheep farmer

Answer 43

* Case study of a sheep farmer with prosopagnosia. Man could not identify face neither the age or gernder of face that was presented to him (severe case). * Unable to name or recognize famous faces or determine age or gender of human faces * Was able to recognize and discriminate sheep with very high accuracy (~90%). As a sheep farmer, he learned to distinguish between sheep visually. * There is selective face processing in the brain

Question 44

Agnosia subtypes

Answer 44

* The location of the deficit along the visual information processing pipeline determines impairment * **Apperceptive agnosia:** Problems perceiving objects (faces for prosopagnosia look contorted). * **Associative agnosia:** Problems assigning meaning or labelling objects (can’t recognize familiar famous faces for prosopagnosia). Cannot recognize something that is familiar.

Question 45

Apperceptive visual agnosia

Answer 45

* A failure in recognizing objects due to problems with perceiving the elements of the objects as a whole. Can still detect specific features but cannot group them as a whole. * Single visual feature perception (e.g., color, motion) are relatively intact. Can still reach/grasp for obkjects - motion perception is intact. * Problems with perception and discrimination of objects * Impairment is in grouping visual features to form perceptions that can interpreted as meaningful * Cannot copy image but can draw from memory.

Question 46

Associative visual agnosia

Answer 46

* An inability to associate visual input with meaning * Problems on tests that require accessing information from memory * Drawing objects from memory * Naming objects * Indicating the functions objects * Determining if a visual object is a possible or impossible object *Can copy image but cannot draw from memory * Cannot access the information they have about the object in their memory tto what they are seing.

Question 47

Bottom-up and top-down processing

Answer 47

**Bottom-up processing:** * Information from the eyes to primary visual cortex propagates down the “what” and “where” pathways * Does not require specific knowledge of the stimulus **Top-down processing:** * Information from final stages of visual pathway processing is sent back to the visual cortex to exert influence * Leveraging knowledge or expectations that are in the sensory stimuli

Question 48

Constructivist Theory of Perception

Answer 48

A Constructivist Theory of Perception * A top-down theory of perception * Perception is influenced by stored knowledge and context - Mental models - mental models of how things work and we activate these mental models when we perceive. - We generate a mental model of the world based on the sensory inputs and we will use these mental models to make predictions. * We make unconscious inferences to interpret and to predict sensory data

Question 49

Illusions

Answer 49

**Illusions demonstrate inferences** * Unconscious inferences and assumptions guide perception. With these assumptions, you can be misled which leads to illusions. If you remove these assumptions it can change your perception. * When the assumptions are incorrect, illusions result: - Ponzo and “monster” illusion: assumptions about depth cues - The world is lit from above: assumptions about shadow cues - Ames Room: assumptions about size constancy - Color perception effects: assumption of context effects * Whatever is hitting your retina, it can be iinnterpreted and represented differently depending on the context and assumptions you bring to mind. There is not a one to one relationship between your retinal image and the mental representation you have of perception.

Question 50

Ambiguous Bistable figures

Answer 50

Ambiguity in the sensory data: the visual input * Your brain will rely on certain cues to perceive these. * You will see what you are more familiar with.

Question 51

Gestalt organizational principles

Answer 51

* Gestalt approach to perception states the whole that is perceived is greater than the sum of its parts. You do not jusr count up feature in your visual field. We naturally want to see objects a whole entities (top down processing) * There are fundamental organizational principles meant to deal with ambiguity in our environment * Constraints to guide interpreting sensory input * These principles are based on knowledge and experience (top down processes) and shared among people

Question 52

What are Gestalt's organizational principles?

Answer 52

**The principle of experience** * Figure ground segmentation **Visual grouping principles**: expectatiions of how elements we see are grouped together. * Principle of proximity * Principle of closed forms * Principle of good contour * Principle of similarity

Question 53

Principle of experience | Gestalts

Answer 53

* Image segmentation (figure-ground) depends on sensory input, detect edges or shadows. You segment visual info into a foreground, background, edges, shadows (bottom up process) * Experience and knowledge also drives figure-ground segmentation * Regions perceived as the figure are the ones that are more familiar and more easily named to the observer. We see what we are familiar with.

Question 54

Familiarity effects on segmentation

Answer 54

People are more likely to state that the white part in the first row is the object whereas the balck part in the second is the object. - This because the white part in the first row is shaped like familiar objects (cowboy bootss, butterfly, grapes)

Question 55

Principles of proximity

Answer 55

Objects or features that are close to one another in a scene will be judged as belonging together. Things that are close together are part of the same package.

Question 56

Principle of closed forms

Answer 56

We see a shape in terms of closed forms, and we like to see items that enclosed as whole

Question 57

Principle of good contour

Answer 57

We perceive objects as continuous where it is expected that it is continuous. You expect shapes that are sharp and smooth. * We perceive objects as continuous in cases where it is expected tha they continue.

Question 58

Principle of similarity

Answer 58

We organize objects or features of a scene based on similarity * when all else is equal we organize objects based on similarity.

Question 59

Context affects interpretation

Answer 59

Gave this image to children at two different time points (one in october and one during easter). * Children was more likely to say it wass a suck (in october, ducks were present at the zoo) * On easter sunday, rabbit wass more likely.

Question 60

Direct models | J.J Gibson

Answer 60

An alternate account: Direct models * We do not need to create these mental models, we do not need to infer. The cues in your environment will guide how your sensory information is processed. *No mental model for sensory input to guide perception and action * Perception involves using information directly from our environment directly, without transforming it in our minds * **A passive bottom-up approach to perception ** * States that we do not need to use assumptionss or prior knowledge to know what we see.

Question 61

How do direct models work?

Answer 61

* First, to understand, perception must be studied in the real world, an ecological approach (JJ Gibson). We need to study perception in the real world. * This is because the ambient optical array (AOA) that reaches the retina has enough information to direct perception and movement * This works because there are cues (computational tricks) in the AOA (not in the mind) that are used to guide perception and action

Question 62

Texture gradients give the appear of depth

Answer 62

* Variations in the surface of an object gives you cues about the distance. * The density of a texture (gradient) provides information about distance * Near objects are farther apart and Far objects are closer together * Incremental changes in texture can provide information about your movement and distance * Closer together cobble stone = illusion that is further.

Question 63

Topological breakages

Answer 63

* Discontinuity created by the intersection of two textures. This is what allows you to see it a two seperate objects. - allows you to perceive edges - bottom-up heavy processing * Provides information about edges of object and aids in object identification

Question 64

Direct models of perception

Answer 64

* We don’t need to create a mental model of the world * What we perceive from the environment is to help guide actions. We pick up these cues from the environment automatically. They tell us how to act, what we are perceiving. * Cues provides information on the potential function of an object and are perceived directly, immediately * Buttons, levers, slots *Gibson thought that action and perception were heavily linked. Something that comes naturally (reflect like). * You have a perception that allows you to know how to engage with these actions. Influence of knowledge here is very limited.

Question 65

Theories of visual object recognition

Answer 65

* We create an internal representation of it for recognition. * Where we go to engage in recognition is memory (what we hold in memory) * Some theories focus on how basic visual elements are processed and then recognized * Pattern recognition theories emphasize: * Identifying a pattern (the data) in visual input * Matching the pattern in visual input to existing patterns (concepts) stored in memory. * A percept (trace) represents the visual input pattern that probes long-term memory traces, looking for a match. Probe might match a bunch of memory traces, but the one with the most overlap will be used. * The highest similarity between the probe and memory trace will determine recognition. * Question: What is the probe being compared to in long-term memory?

Question 66

Template matching theory

Answer 66

* Every object has a ‘template’ in long-term memory. A catalogue of patterns for each encounter you have had. * too simplistic * computationally demanding * 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 Problems with template theory: * very computationally demanding * Lots of variability in the objects that we see * According to template theory, you would have a different template for all of thesse varieties.

Question 67

Prototype theory

Answer 67

* A prototype is the average representation of an object concept * what is the most typical thing about that object. * recognition is determined by a ‘good enough’ match (resemblance) * allows for ‘flexible’ object identification - you do not have this template matching, it is based more on resemblance than a 1 to 1 match. Good enough match = still recognizing.

Question 68

Feature detection

Answer 68

* Visual input is broken down into individual parts (features). Visual input is first decomposed into features. * each feature is processe separately and then put togeher to recognize the thing. * the combination of features is used as a pattern for recognition to compare to a prototype

Question 69

Example of feature detection: Recognition by components

Answer 69

* All objects are reducible to a set of features, geons, basic geometric shapes. * Geons are 3D shapess that combine to form any object to help assist in object recognition. - When you recognize something, you first break it down into a set of features (a geon) and then you compare the configuration of those geons in your visual perceptual input to the configuration of geons you have in memory and a match means recognition. . * Recognition involves: * Mentally separating a visual object into geons * Examining the arrangement * Finding best match of arrangement to memory representations of geon combinations

Question 70

Managing perspective shifts

Answer 70

* Geons have distinct properties that we can perceive from any angle/view/perspective. - geons can be identified by different perspectives. - do not need a long list held in memory - computationally economical * Thus, such feature detection theories can account for how we can recognize objects with shifts in perspective

Question 71

Recognition in context

Answer 71

* Scene consistency effect: an object in a place that you would expect is named more accurately than one that you wouldn't * Study asked people to identify objects that were superimposed on a scene that would be consistent with the object or inconsisten. Ex; Pinecones on forest scene or on a bathroom scene. * They took EEG measurements while doing this and found that objects and scnene pairs were named more accurately in the consistent one. * And what's cool is when you look at the brain data what you find is that those objects in an inconsistent scene elicited more of a negative potential in the N 400 response. This is with the EEG and this response signifies a semantic violation, it suggest that we use semantic knowledge to drive object regonition

Question 72

Binoclular disparity

Answer 72

* disparity will be greater with objects closer to your eyes * it is the disparity between what both eyes see.

Question 73

Steriopss

Answer 73

using binocular disparity to perceive depth

Question 74

motion parilax

Answer 74

* object close to you when you are moving will change more and faster then objects far away from you