University of Waterloo PSYCH 207 - Chapter 7 (Concepts and Categorization)

A concept

a mental representation that groups or categorizes objects, events, or pattern

A category

Defined as a class of similar things (objects or entities) that share one of two things

Mental buckets

Concepts help us ___________, concepts also allow us to ________________

establish order in our knowledge base

Categorize, giving us mental 'buckets' in which to sort the things we encounter

Categorization allows us to make ________________ and act accordingly

predictions

eg. triangle in the water -> garbage or shark

What is the classical view of concepts?

Dominant view until the 70s and dates back to Aristotle

Centers around the belief that all examples of a concept share fundamental "FEATURES"

Features are individually ______________ and collectively _______________

Necessary and sufficient

What are the implications of the classical view of concepts?

1. A concept mentally represents a LIST OF FEATURES (abstractions -> not specific)

2. Membership in a category is clear cut

3. All members within a category are created equal

How did people challenge the classical view of concepts

1. Not all members are created equal

2. People don't really have a list of representations (lists are not constant across groups of people)

What is the prototype view of concepts

1. Denies the necessary and sufficient feature list

2. Believes in a view of mental PROTOTYPES (hold typical features)

3. Often refers to the "FAMILY RESEMBLANCE" STRUCTURE OF CONCEPTS (the more features a member possesses, the more typical it is, few features are shared by all)

KEY: "core representationS" NOT rigid boundaries

Basic level of categorization

A level of categorization hypothesized as the "natural" and most informative level, neither too specific nor too general.

KEY: The optimization between the goals of grouping in important ways, but not too specific

KEY: This is part of prototype view, the prototype view is good because it better encompasses how different features more more typical than others

superordinate levels of categories

A level of categorization broader than the basic level that includes exemplars that can be quite dissimilar from one another.

subordinate levels of categories

a level of categorization narrower than the basic level

What are some problems with the prototype view

1. It does in-fact fail to capture people's knowledge about the limits of conceptual boundaries

2. typicality rating

The exemplar view of concepts

asserts that concepts include representations of at least some actual individual instances called EXEMPLARS

1. This explains why people have trouble STATING Features, but are good at IDENTIFYING them

2. Typical instances are more likely to be stored than less typical ones (typical ones are also easier to process)

3.

Example study of exemplar view

BUILDERS VS. DIGGERS

KEY of this experiment is that specific prior examples are more influential on categories than simple defining features

Participants took longer to classify, and made more errors in categorizing the negative marches than the positive items (the "positive items" were visually similar to the "know builder" aka the target, and therefore they were easier to be labelled as positive matches)

What are the problems with the exemplar view?

1. Fails to explain which instances will be saved as exemplars and which will not

2. Does not explain how different exemplars are "called to mind" at the time of categorization

3. This model has difficultly accommodating data from large and complex categories

What is the schemata/scripts view? What are problems with it?

Frameworks of knowledge

KEY: There are sub-schemata and super-schemata

KEY: Similar to prototype (abstractions) and exemplar (instances)

Problems - does not specify clear enough boundaries, is not empirically testable

What is the knowledge based view?

More purpose based -> what makes up the category of things you would take from a fire?

What are the two ways to divide up the structures? What are the problems with each category?

Similarity based: Classical, prototype, exemplar

Problems: Similarity is meaningful only in certain respects (plum and lawnmower DO both weigh less than 100lbs)

Explanation based: Schemata, knowledge-based

Describe concept attainment strategies

This is for the test-card-evaluating-study (the participants were given a card after an initial "correct one" is shown and were told to hypothesize if they thought that card fit the 'hidden rule', after they judged the card, they were told if it was infact valid or not)

Strategies:

1. Simultaneous scanning: people who pursued this strategy used each card to test and rule out multiple hypotheses (difficult and taxing)

2. Successive scanning: Same as above, but one at a time (less efficient, more manageable)

3. Conservative focusing: findings a card that illustrated the concept, then choosing to test other cards that varied from it in only one aspect (good strat chief, but very dependent on the sequence of the cards)

The effectiveness of a strategy depends on the task conditions (in your head, or not . . . what the stimuli you are trying to remember is (different than faces))

TWO BEST strategies were conservative focusing and SIMultaneous scanning

These concepts are nominal: have precise definitions

Changing colors of squares experiment shows what?

How concepts are acquired in the brain

When trying to identify what the prototype might be like from the test images, participants used the frontal and parietal regions of the right hemisphere (because early processing of images is more about VISUAL PATTERNS than RULES). These processes begin to SHIFT LEFT as abstract rules are established

The basal ganglia is also involved in this process (processes feedback in order to promote learning)

"Learning the grammar from a string of letters" study . . . what does it prove?

Participants learning letter strings that followed the grammar made fewer errors than did control participants learning random letter strings

KEY: Participants who were told ahead of time that letter strings followed certain complex rules remembered strings more poorly than participants who were simply asked to memorize particular letter strings but where not told anything about the strings "following a structure".

CONCLUSION: When complex underlying structures exist (such as grammar), people are better off memorizing exemplars than trying to figure out what the structure is, primarily because participants who try to guess the structure often induce or invent incorrect rules or structures

What are the five factors that encourage people to store individual exemplars

1. Being required to distinguish between individual differences (important to know poodle and pitbull are different)

2. Certain exemplars are more pronounced in memory by nature (your own dog)

3. Relevant dimensions of variation are not apparent to a novice

4. Exemplars may belong to many different categories at the same time (more pronounced)

5. In natural settings, we take in specific circumstances without knowing we'll be called on to use them later

What were the main takeaways for the doctor vs. policeman facial attribute study

Policemen and doctors have a number of features that are somewhat internally common, but only one feature that is across the board internally common to each

1. If people identified the test image (only included the common feature, and used all features from the other to confuse) incorrectly, they were using family resemblance, if they did it correctly, they used criterion feature approach

2. KEY which approach they used depended on the instructions (recognize the pictures -> family resemblance, internally common features -> criterion feature approach)

When attempting to remember a story that is based on a typical "script" experience

People will add information that was not originally there that is indicative of the script

Psychological essentialism

The idea that people possess implicit theories about fundamental characteristics that all instances of a concept contain or embody.

What are the three "kinds of concepts"? What is a key to these differences?

Nominal-kind concepts: concepts that have a clear definition (connects to necessary and sufficient features)

Natural-kind concepts: naturally occurring in an environment (gold, tiger) (essentialism)

Artifact concepts: constructed to accomplish a task (knowledge based approach)

KEY: Natural kind concepts are most sensitive to molecular transformation, where as artifact concepts are most sensitive to functional changes