lecture 8 – visual memory 1 through associations between new material and familiar material. but...

Lecture 8 – Visual Memory 1

• Through associations between new material and familiar material.

• But how do we develop associations?

• In particular, do we associate individual objects in the world with other individual objects? Or classes of objects with other classes?

How is new learning influenced by WWAK?


What do you think of when I say, “Cat?”

Probably, “Dog.”

But which dog?

A specific image? Or a general image which captures some essential ‘dogness’?

Example:


Dog vs. Dogs

In the next slide, notice that every dog is different in some way. They vary in colour, in posture, even in size a little bit.

Yet, there is some general ‘dogness’ on display, as well.

That suggests two ways we can represent things.


Two ways to represent things

1. As a specific object, with great detail

• Useful for controlling specific responses (e.g. picking up a given cup in a given location)

• Does not generalize well (e.g., handle on next cup may be thinner than handle on this cup)

• Store long enough to execute response.



2. As a general object, with less detail

• Contains the information that may be relevant in a similar but not identical situation

• E.g., are cups as delicate as soap bubbles? How do dogs behave when you reach for the milkbones?

• These we may store for years.



Each of these ways has its own purpose.

If you want to behave towards some object in the world, you need a detailed representation of that specific object – size, shape, location, texture…

If you want to learn a lesson for future reference, you need a less detailed (visual) representation which generalizes better.


Three levels of detail

1. Detailed current representation.

2. Stable aspects of a familiar situation (e.g., your living room). Abstract representation, less detail.

3. General aspects of visual form (e.g., what does a sofa look like – not your sofa, but sofas in general?). Least detailed


Three levels of detail

In what follows, I will make these points:

• Representations at different levels of detail vary in how much it is worth remembering them over the long term.

• With more general representations, we use imagery to improve memory either deliberately (mnemonics) or automatically (dual-coding).


Three levels of detail and their role in memory

1. Detailed current representation• Melcher (2001)• Simons & Levin (1998)• Standing (1973)

2a. Stable aspects of familiar situation• Method of loci• Nickerson & Adams (1979)

2b. General aspects of visual form• Paivio’s Dual Code theory


1. How much detail can we get into a stimulus representation?

• For a short time – a lot

• Melcher (2001) – memory for scenes accumulated over a series of brief views as though scene had never been out of sight.

• Effect did not build up across days

Memory for detailed current stimulus


Memory for detailed current stimulus

Simons & Levin (1998)

• Change blindness – people don’t notice changes in visual scene after brief interruption (when the scene is of little importance)

• abstract expectations about a scene allow us to focus on some small part that we use to check for moment-to-moment consistency


But what about Standing (1973)?

Standing (1973):

• Good performance on recognition of 10,000 faces seen in photographs over several days

• Recognition tested with a set of several hundred of these photographs (plus foils)

• But did subjects store whole faces or just salient bits?


What do these studies tell us?

• We store detailed information about a visual scene only on the scale of seconds/minutes (long enough to execute a response).

• We may store over a long period (e.g., days) just enough information to distinguish one scene from another.

• Don’t use these repns. for mnemonics.


Memory for stable aspects of a situation

Stable aspects of a situation worth remembering, because likely to occur again

Because these aspects are well-learned, they can be used to form associations to new material.

Method of loci

• associate to-be-learned material with familiar locations, such as rooms in your house.


Memory for stable aspects of a situation

However, stable aspects of a situation that never influence a response are not worth remembering.

Nickerson & Adams (1979)

• US students were poor at discriminating line-drawing of real dime from fakes.

• How many maple leaves on a penny?


What do these studies tell us?

Some stable aspects of a situation are meaningful, and these are stored in LTM.

Other aspects are not meaningful and these are not stored in LTM.

Memories that we keep around in the long term can be used as the basis for associations in new learning (e.g., through method of loci).


General aspects of visual form

The most abstract forms are the most general – they have the least detail in them, so apply most widely to new situations.

Because they are general, such forms are highly overlearned (frequently experienced).

Because they are overlearned, such forms can help us remember experiences, even when we don’t deliberately use mnemonics.


General aspects of visual form

Paivio’s Dual Code theory:

• Least-detailed representation of any object, situation, or event is a word that names it.• For example, the word ‘dog’ captures that essential dogness without capturing any of the details that make a particular dog particular.• Imageable words are more memorable than words that name non-imageable things


Paivio’s Dual Code theory

1. Distinguish between high-imageability words and low-imageability words.

High imageability Low imageability

Firetruck DutyTree IdeaCake TruthVolcano Love



2. Compare recall for high- vs. low-imageability words.

Paivio, Smythe, & Yuille (1968)

• Cued recall. Cue & target varied in imageability.

• Recall was best when both were high, worst when both were low, intermediate for one of each.



In method of loci, there is no necessary connection between two associates (e.g., hamburger and bathroom).

• connection must be made explicitly

In Paivio’s study, pre-existing associations (e.g., “tree” with image of tree) are used.


Review – Memory for detailed representations

• contains significant detail

• supports responding in a dynamic world

• valid (accurate as a description of the world) only on the time scale of seconds or minutes

• memory persists for a short time only


Memory for stable aspects of familiar situations

• contains less detail, but still distinguishes between individual objects/locations (e.g., my sofa and yours)

• supports activities that don’t require dynamic, constantly-updated information (e.g., planning routes).

• supports method of loci


Review – Memory for general visual forms

• general visual forms are highly-overlearned.

• as a result, they make good associates for to-be-learned material.

• Paivio: imageable words more likely to be recalled, because automatically encoded using both verbal and image representations.

lecture 8 – visual memory 1 through associations between new material and familiar material. but...

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