L6: Mental Images and Propositions

Knowledge Representation

The form for what you know in your mind about things, ideas, events, and so on in the outside world.

Knowledge Structures

For centuries philosophers have done exactly that. In classic epistemology—the study of the nature, origins, and limits of human knowledge—philosophers distinguished between two kinds of knowledge structures:

• Declarative Knowledge

• Procedural Knowledge

Declarative Knowledge

• Knowing “that”

• Refers to facts that can be stated, such as:

  • The date of your birth

  • The name of your best friend

  • The way a rabbit looks

Procedural Knowledge

• Knowing “how”

• Refers to knowledge of procedures that can be implemented, such as:

  • The steps involved in tying your shoelace

  • Adding a column of numbers

  • Driving a car

Two Main Sources of Empirical Data on Knowledge Representation

• Standard Laboratory Experiments

• Neuropsychological Studies

Standard Laboratory Experiments

• Researchers indirectly study knowledge representation because they cannot look into people's mind directly.

• They observe how people handle various cognitive tasks that require the manipulation of mentally represented knowledge.

Neuropsychological Studies

• Researchers typically use one of two methods:

  1. They observe how the normal brain responds to various cognitive tasks involving knowledge representation.

  2. They observe the links between various deficits and knowledge representation and associated pathologies in the brain.

Communicating Knowledge: Picture vs. Words

Knowledge can be represented in different ways in your mind: it can be stored as a mental picture, or in words, or abstract propositions.

Communicating Knowledge: Pictures vs. Words

(a) - _____

(b) - _____

(c) - _____

(a) - Pictorial Analogous Image

(b) - Word

(c) - Fundamental propositional representations that are in a pure abstract “mentalese”; neither verbal nor pictorial.

Picture

• _____ is relatively analogous (i.e., similar) to the real world object it represents.

• _____ shows concrete attributes, such as shape and relative size.

Symbolic Representation

• Relationship between the word and what it represents is simply arbitrary.

• Ex. If you had grown up in another country like Germany or France, the word Katze or the word chat, respectively, wood instead symbolize the concept of a cat to you.

Imagery

• Mental representation of things that are not currently seen or sensed by the sense organs.

• Represent things that you have never experienced.

• May involve mental representations in any of the sensory modalities.

Dual Code Theory

• We use both pictorial and verbal codes for representing information.

• These two codes organized information into knowledge that can be acted on, stored somehow, and later retrieved for subsequent use.

Analog Codes

• It resembles the objects they are representing.

• The mental images we form in our minds are analogous to the physical stimuli we observe.

Symbolic Code

Form of knowledge representation that has been chosen arbitrarily to stand for something that does not perceptually resemble what is being represented.

Propositional Theory

• Suggests that we do not store mental representations in the form of images or mere words.

• We may experience our mental representations as images, but this images are “epiphenomena”—secondary and derivative phenomena that occur as a result of other more basic cognitive processes .

• Our mental representations more closely resemble the abstract form of a proposition.

Proposition

Basically an assertion which may be either true or false.

Example: To describe the picture, you could say, “The table is above the cat”. You could also say, “The cat is beneath the table.” Both of these statements indicate the same relationship as “above the cat is the table.”

Using Proposition

• Propositions may be used to describe any kind of relationship. Relationships include actions of one thing or another, attributes of a thing, positions of a thing, class membership of a thing, and so on.

• Any number of prepositions may be combined to represent more complex relationships, images, or series of words.

• Key idea is that the propositional form of mental representation is neither in words nor in images.

• Thus, a proposition for a sentence would not retain the acoustic or visual properties of the words.

Propositional Representations of Underlying Meanings

We may use prepositions to represent any kind of relationship, including actions, attributes, spatial positions, class membership, or almost any other conceivable relationship. The possibility for combining propositions into complex propositional representational relationships makes the use of such representations highly flexible and widely applicable.

Type of Relationship: Actions

Representation in Words: A mouse bit a cat

Prepositional Representation: Bite [action] (mouse [agent of action], cat [object])

Imaginal Representation:

Type of Relationship: Attributes

Representation in Words: Mice are funny

Prepositional Representation: [external surface characteristic] (furry (attribute), mouse [object])

Imaginal Representation:

Type of Relationship: Spatial Positions

Representation in Words: A cat is under the table

Prepositional Representation: [vertically higher position] (table, cat)

Imaginal Representation:

Type of Relationship: Class or Category Membership

Representation in Words: A cat is an animal.

Prepositional Representation: [categorical membership] (animal[category], cat[member])

Imaginal Representation:

Functional Equivalence Hypothesis

• Visual imagery is not identical to visual perception, but it is functionally equivalent to it.

• Functionally equivalent things are strongly analogous to each other.

• Functionally equivalent images are analogous to the physical percepts they represent.

• Suggests that we use images rather than propositions.

Principles of Visual Imagery

Considering the fact that themes and ideas can be quite complex it's important to consider how they develop throughout a text.

1. Our mental transformations of images and are mental movements across images correspond to those of physical objects and percepts.

2. The spatial relations among elements of a visual image are analogous to those relations in actual physical space.

3. Mental images can be used to generate information that was not explicitly stored during encoding.

4. The construction of mental images is analogous to the construction of visually perceptible figures.

5. Visual imagery is functionally equivalent to visual perception in terms of the processes of the visual system used for each.

Neuroscience and Functional Equivalence

• Evidence for functional equivalents can be found in neuroimaging studies.

• Participants either viewed or imagined an image.

• Activation of similar brain areas was noted, in particular, the frontal and parietal regions.

• Imagery can evoke responses in high level visual brain areas and the visual primary cortex.

Mental Rotations

Involves rotationally transforming an object's visual mental image.

Ex. You can physically rotate a water bottle hold in your hands, you can also imagine a water bottle in your mind and rotate it in the mind.

Linear Function

Degree which the figures were rotated

Degraded Stimuli

Stimuli that are blurry, incomplete, or otherwise less informative.

Practice Effects

Improvements in performance associated with increased practice.

Is there any physiological evidence for mental rotation?

One type of study involves the brains of primates, animals whose cerebral processes seem most closely analogous to our own. Using single cell recordings in the motor cortex of monkeys, investigators found some physiological evidence that monkeys can do mental rotations. Teach monkey had been trained physically to move a handle in a specific direction toward the target light used as reference point. Wherever the target light appeared, the monkeys where to use that point as a reference for the physical rotation of the handle.

During this physical rotations, the monkey's cortical activity was recorded. Later, in the absence of the handle, the target light again was presented at various locations. The cortical activity again was recorded. During these presentations, activity in the motor cortex showed an interesting pattern. The same individual cortical cells tended to respond as if the monkeys were anticipating the particular rotations associated with particular locations of the target light.

True

T OR F: The primary motor cortex is activated when participants imagine manually rotating a stimulus. Thus, not only are imagery and perception functionally equivalent in many psychological studies, neuropsychological techniques also verify this equivalence by the most rating overlapping brain activity.

Gender and Mental Rotation

• A number of studies have highlighted and advantage for males over females and mental rotation tasks, but others have not.

• A number of studies that have not found gender differences have used characters (like letters or numbers) for mental rotation; therefore, it is possible that the rotation of characters engages different processes than the mental rotation of other objects.

Image Scaling

The key idea underlying research on image size and scaling is that we represent and use mental images in ways that are functionally equivalent to our presentations and use of percepts. In other words, we use mental images the same way we use our actual perceptions.

Resolution

Level of detail contained in an image

Scaling

Process of resizing a digital image.

Image Scanning

• Stephen Kosslyn has found additional support for his hypothesis that we use mental images in ________.

• The key idea underlying _______ research is that images can be scanned in much the same way a physical percepts can be scanned.

• Furthermore, our strategies and responses for ______ should be the same as for perceptual scanning.

True

T OR F: A means of testing the functional equivalence of imaginal scanning is to observe some aspects of performance during perception scanning, and then compare that performance with performance during imaginal scanning.

Representational Neglect

• A person asked to imagine a scene and then describe it ignores half of the imagined scene.

• For example, if a person with representational neglect we're asked to describe his or her kitchen, he or she would do so accurately. However, if the same person were asked to describe the kitchen from the refrigerator, then he or she would demonstrate neglect.

Johnson-Laird’s Mental Models

1. Propositions

2. Images

3. Mental Models

Mental Models

• ______ our knowledge structures that individuals create to understand and explain their experiences.

• Models are controlled by the individuals implicit theory about their experiences (beliefs; perspective).

• Faulty ______ are responsible for many errors in thinking and experience is a power tool to repair it.

Right Hemisphere

• Appears to represent manipulate visousplatial knowledge in a manner similar to perception.

• Represents knowledge analogous to our physical environment.

Left Hemisphere

• Appears to represent and manipulate verbal and other symbol based knowledge.

• Has the ability to manipulate imaginal components and symbols and generate entirely new information.

2 Kinds of Images

• Visual Imagery

• Spatial Imagery

Visual Imagery

Refers to the use of images that represent visual characteristics such as colors and shapes.

Spatial Imagery

Refers to images that represents spatial features such as depth, dimensions, distances, and orientation.

Images actually may be stored (represented) in different formats in the mind

While examining visual imagery, researchers have found that _________, depending on what kind of image is involved. Consider the case of L.H., who had a head injury at age of 18.

Spatial Cognition

• Deals with the acquisition, organization, and use of knowledge about objects and actions in 2D and 3D spaces.

• Studies are based on what we have perceived by looking at and imagining visual stimuli.

Cognitive Maps

• Internal representation of our physical environment, particularly centering on spatial relationships.

• Seem to offer internal representation that stimulate particular spatial features of our external environment.

Cognitive Maps of Rats

• In the first group, the rats had to learn the maze. Their reward for getting from the start box to the end box was food.

• Second group of rats also was placed in the maze, but this rats receive no reinforcement for successfully getting to the end box.

• Third group of rats receive no reward for 10 days of learning trials. On the 11th day, however, food was placed in the end box for the first time.

Cognitive Maps of Bees

Bees not only can form imaginary maps for getting to food sources but also can use a somewhat symbolic form for communicating that information to other bees.

Cognitive Maps of Pigeons

Homing pigeons are noted for their excellent cognitive maps. These birds are known for their ability to return to their home from distant location. This quality made the birds useful for communication in ancient times.

Cognitive Maps of Humans

Humans seem to use three types of knowledge when forming and using cognitive maps:

1. Landmark knowledge

2. Route-road knowledge

3. Survey knowledge

Landmark Knowledge

Information about particular features at a location and which may be based on both imaginal and propositional representations.

Route-road Knowledge

Involves specific pathways for moving from one location to another. It may be based on both procedural knowledge and declarative knowledge.

Survey Knowledge

Involves estimated distances between landmarks, much as they might appear on survey maps. It may be represented imaginary or propositionally (e.g., in numerical specified distances).

Heuristics

• Informal, intuitive, speculative strategies that sometimes lead to an effective solution and sometimes do not.

• The use of heuristics in manipulating cognitive maps suggests that prepositional knowledge affects imaginal knowledge.

True

T OR F: The distortions seem to reflect a tendency to regularize features of mental maps. Thus, angles, lines, and shapes are represented as more like pure abstract geometric forms than they really are.

Right-angle Bias

People tend to think of intersections (e.g.,street crossings) as forming 90° angles more often than the intersections really do.

Symmetry Heuristics

People tend to think of ships (e.g.,states or countries) as being more symmetrical than they really are.

Rotation Heuristics

When representing figures and boundaries that are slightly slanted (e.g.,oblique), people tend to distort the images as being either more vertical or more horizontal than they really are.

Alignment Heuristics

People tend to represent landmarks and boundaries that are slightly out of alignment by distorting their mental images to be better aligned than they really are (e.g, we distort the way we line up a series of figures or objects).

Relative-position Heuristics

The relative positions of particular landmarks and boundaries is distorted in mental images in ways that more accurately reflect people's conceptual knowledge about the contexts in which the landmarks and boundaries are located, rather than reflecting the actual spatial configurations.