Lecture 22 - Week 13 Thursday - Visual Mental Imagery

Paired Associate Paradigm - What is the paired associate paradigm, its results, and its importance?

The paradigm involves a subject being read word pairs (e.g., "Car-House") and later being prompted with the first word to recall the second. Results showed that concrete words (C-C like "Truck-Tree") are remembered much better than abstract words (A-A like "Justice-Truth"). This is important because it suggests that concrete words allow for dual coding—we store both the verbal word and a visual mental image, providing two ways to retrieve the memory.

Structured Representations - What two things do structured representations do?

They specify relationships between different parts of a representation. 2. They create a complex structure out of simpler parts (e.g., a "sentence" structure built from "word" parts).

Propositions vs. Images - For "A ball is on a box," what is the difference between a propositional and an image description?

A Proposition is a list of relations and arguments (e.g., ON [BALL, BOX]) that is abstract and doesn't "look" like the scene. An Image is a depiction where the spatial relationship is inherent—the "ball" is physically above the "box" in the mental representation, mirroring the actual physical space.

Epiphenomenon - What is an epiphenomenon?

An epiphenomenon is a secondary effect or byproduct that arises from a process but has no causal influence itself. In the imagery debate, some argue that mental images are just "mental exhaust"—we might see them while we think, but the actual "thinking" is being done by underlying propositional logic.

Homunculus Problem - What is the homunculus problem?

This is the "little man" fallacy: if we say there are "pictures" in our head, it implies there must be an internal eye (a homunculus) to "look" at them. This leads to an infinite regress, because you'd then need another even smaller man inside the homunculus's head to look at his mental images.

Properties of Mental Imagery - What are the 4 properties that support mental imagery as a separate system?

Rotation: We can mentally "spin" objects, and the time it takes correlates to the degree of rotation. 2. Size/Scaling: It takes longer to see small details on a "small" mental image than a "large" one. 3. Scanning: It takes longer to mentally "scan" across a long distance in an image than a short one. 4. Brain Mapping: Imagery activates the same visual cortex areas as actual perception.

Image Processing - What are the 4 processes of image processing?

Generation (creating the image). 2. Maintenance (keeping it in the "mind's eye"). 3. Inspection (looking at details of the image). 4. Transformation (moving or rotating the image).

Image Generation - What is image generation?

It is the process of taking information stored in Long-Term Memory (LTM) and "fleshing it out" into a visual representation in our consciousness.

Generation Timing - Does image generation happen all at once?

No, it happens piece-by-piece. Evidence shows that images with more parts (e.g., a complex map or an uppercase 'E' vs. a lowercase 'L') take longer to generate. We "draw" the image in our mind sequentially rather than flashing it up like a photograph.

Ventral vs. Dorsal Imagery - How does brain damage affect visual vs. spatial imagery?

Damage to the Ventral pathway ("what" pathway) impairs visual imagery (knowing what an object looks like, like color or shape). Damage to the Dorsal pathway ("where" pathway) impairs spatial imagery (knowing where things are or mentally navigating a room).

Maintenance - What is maintenance?

Maintenance is the active, attention-demanding process of holding a mental image in focus. Because mental images are highly "volatile," as soon as your attention shifts to something else, the image is lost.

Inspection - What is inspection? Give an experiment.

Inspection is the ability to "re-examine" a mental image to discover new details you didn't consciously note during generation. Experiment: Subjects are asked to mentally "fold" a net or combine two mental shapes (like a 'D' and a 'J') to see what new object they form (like an umbrella). This proves we can draw new conclusions from mental images.

Transformation - What is transformation?

Transformation is the ability to mentally rotate, move, or resize an image in our mind to see how objects would interact in a physical plane. Ex. Mentally "moving" furniture in your room to see if it fits before actually lifting it.

History & Imagery Debate - Why was the study of visual mental imagery historically rejected, and what was the core of the "imagery debate"?

Early introspectionists believed imagery was the heart of consciousness, but the field moved away from it because imagery is a private process that cannot be objectively observed. The subsequent "imagery debate" centered on whether these images are functional (acting like actual internal pictures) or merely epiphenomenal—a byproduct of language-based propositional thought that doesn't actually help us solve problems.

Structural Differences - How do propositions and images differ in their formal characteristics and truth values?

Propositions are governed by a formal syntax (rules of representation) and possess inherent truth values (they are either true or false). In contrast, images lack a formal syntax and do not have a truth value until they are described or interpreted through language.

The Crude Theory & Overlap - How does the "crude theory" explain the link between vision and imagery, and what does it predict?

This theory posits a "visual experience screen" that is powered by both perception and memory representations. Because of this shared mechanism, the theory predicts a significant perceptual overlap, meaning that brain damage or cognitive interference that affects actual vision will often impact mental imagery in the same way.