Cognitive Psych Exam 3

Conceptual Knowledge

Enables us to recognize objects & events & to make inferences about their properties

Concept

Mental representation used for a variety of cognitive functions

Categorization

The process by which things are placed into groups called categories

Categories are all possible examples of a particular concept

Why They’re Useful:

• Help to understand individual cases not previously encountered

• Pointers to knowledge

  • Provide a wealth of general info about an item

  • Allow us to identify the special characteristics of a particular item

Definitional Approach to Categorization

Determine category membership based on whether object meets the definition of the category

• e.g. Chair is “a piece of furniture consisting of a seat, legs, back, & often arms, designed to accommodate one person.”

Does not work well

• Not all members of everyday categories have the same defining features

Family Resemblance

Items in a category resemble one another in a number of ways

Allows for some variation within a category

Prototype

Average representation of the “typical” member of a category

Characteristic features that describe what members of that concept are like

An average of category members encountered in the past

Prototype Approach

Prototypical category members are more affected by a priming stimulus

• Hearing “green” primes a highly prototypical “green”

Typicality

Variations within categories (e.g., robins, owls, buzzards, penguins)

High

• A category member closely resembles the category prototype

  • “Typical” member

  • For category “bird” = robin

Low

• A category member doesn’t closely resemble the category prototype

  • For category “bird” = penguin

Typicality Effect

Prototypical objects are processed preferentially

• Sentence Verification Technique:

  • “An apple is a fruit.” Y/N

  • “A pomegranate is a fruit.” Y/N

Highly prototypical objects judged more rapidly

Exemplar Approach

Concept is represented by multiple examples (rather than a single prototype)

Examples are actual category members (not abstract averages)

To categorize, compare the new item to stored examples

• E.g., a sparrow is similar to many bird examples, so we categorize it faster than a penguin

Prototypes or Exemplars?

May use both

We tend to use prototypes when initially learning about a category

We tend to use exemplars more when we better understand a category

• 2 approaches aren’t oppositional, theyre sequential

Hierarchical Organization

Not all categories are the same

• There are different “levels” of categories we can use

Evidence That Basic Level Is Special

Going above basic level → large loss of info

Going below basic level → little gain of info

Semantic Networks

Concepts are arranged in networks that represent the way concepts are organized in the mind

• Node = category/concept

• Concepts are linked

• Which will take longer to categorize?

  • “A canary is a bird”

  • “A canary is an animal”

    • It takes longer to answer “yes” to “A canary is an animal”

    • Than to “A canary is a bird”

• Cognitive economy:

  • Shared properties are only stored at higher-level nodes

  • Exceptions are stored at lower nodes

Spreading Activation

Spreading Activation

Activation is the arousal level of a node

When a node is activated, activity spreads out along all connected links

Concepts that receive activation are primed and more easily accessed from memory

Concepts in the Brain

5 proposals/models of how the brain represents concepts:

• Sensory-functional hypothesis

• Multiple factor approach

• Semantic category approach

• Embodied approach

• Hub-and-spoke framework

Sensory-Functional Hypothesis

Different brain areas may be specialized to process info about different categories

• Double dissociation for categories “living things” and “nonliving things” (artifacts)

• Category-specific memory impairment

Hypothesis:

• Living things → sensory properties

• Artifacts → functions

  • Proposes that our ability to differentiate living things & artifacts depends on a memory system that distinguishes sensory attributes & a system that distinguishes functions

Problems w/hypothesis:

• One patient w/a sensory deficit was better at identifying animals than artifacts—opposite of the hypothesis’ predictions

• Other patients w/brain damage can name some artifacts but not others

  • “Artifacts” are not a homogeneous category

Multiple-Factor Approach

Can be thought of as an extension of the sensory-functional hypothesis that explains data inconsistent w/that hypothesis

Central idea is that we use multiple factors when grouping or organizing concepts

Distributed representation: how concepts are divided within a category

• Animals → motion and color

• Artifacts → actions (using, interacting)

Semantic Category Approach

Proposes that there are specific neural circuits for specific categories

• Participants listened to stories in a scanner

  • (a) Words that activated different places on the cortex

  • (b) Close-up of a smaller area of cortex

  • Note that a particular area usually responded to a number of different words

Embodied Approach

Proposes that knowledge of concepts is based on reactivation of sensory & motor processes that occur when we interact w/the object

• Semantic somatotopy: correspondence between words related to specific body parts & the location of brain activation

However, some brain damaged people who cannot produce actions w/objects can still recognize them, which this approach can’t explain

Hub-and-Spoke Framework

Brain damage can cause category-specific deficits in concept knowledge, but semantic dementia causes global deficits in concept knowledge

• Semantic dementia damages the anterior temporal lobe (ATL)

This framework proposes that areas of the brain that are associated w/specific functions/concepts are connected to the ATL, which serves as a hub that integrates the info from these areas

This framework has also been supported by transcranial magnetic stimulation experiments