Theoretical Perspectives: Information, Language and Cognition Week 14 Lecture notes INF 380E: Perspectives on Information Spring

Why talk about categories? “There is nothing more basic than categorization to our thought, perception, action, and speech.” – Lakoff, p. 5 2

Categories: the classical view (Lakoff) categories were assumed to be containers with things either inside or outside the category things were assumed to be in the same category if and only if they had certain properties in common the properties they had in common were taken as defining the category 3

The Doctrine of Natural Kind Terms the doctrine that – the world consists very largely of natural kinds of things – and that natural languages contain names (called "natural kind terms") that fit those natural kinds 4

Categories Activity Find a partner or two We'll take two minutes to rate each example. – write down your rating – and a reason for your rating 5

Round One: Tables 6

Tables Example #1 How good is this image as an example of a table? Rate it from 1 to 10, with 10 as an excellent example and 1 as a poor example. 7

Tables Example #2 How good is this image as an example of a table? Rate it from 1 to 10, with 10 as an excellent example and 1 as a poor example. 8

Tables Example #3 How good is this image as an example of a table? Rate it from 1 to 10, with 10 as an excellent example and 1 as a poor example. 9

Tables Example #4 How good is this image as an example of a table? Rate it from 1 to 10, with 10 as an excellent example and 1 as a poor example. 10

Tables Example #5 How good is this image as an example of a table? Rate it from 1 to 10, with 10 as an excellent example and 1 as a poor example. 11

Tables Example #6 How good is this image as an example of a table? Rate it from 1 to 10, with 10 as an excellent example and 1 as a poor example. 12

Rosch's objections "First, if categories are defined only by properties that all members share, then no members should be better examples than any other members." "Second, if categories are defined only by properties inherent in the members, then categories should be independent of the pecularities of any beings doing the categorization." 13

Rosch’s evidence prototype effects – asymmetries that demonstrate that certain members of a category are judged as more representative than others 14

What Wittengenstein said “The classical category has clear boundaries, which are defined by common properties.” LW’s counterexample was game – There is no single common property that all games share – Instead the category is united by family resemblances. 15

Categories and words “The senses of a word can be seen as forming a category … with central senses and non-central senses” 16

Austin’s "healthy" example 17

Austin’s foot 18

Round 2: Breakfast! 19

Breakfast Example #1 How good is this image as an example of breakfast? Rate it from 1 to

Breakfast Example #2 How good is this image as an example of breakfast? Rate it from 1 to

Breakfast Example #3 How good is this image as an example of breakfast? Rate it from 1 to

Breakfast Example #4 How good is this image as an example of breakfast? Rate it from 1 to

Breakfast Example #7 How good is this image as an example of breakfast? Rate it from 1 to

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prototypes subcategories or members that have a cognitive status of being a “best example”, or most representative a category 26

ICMs Lakoff: we organize our knowledge by means of structures called idealized cognitive models. 27

But how do we get anywhere if terms don’t have literal meanings? speech acts occur in the context of a background “meaning is created by an active listening, in which the linguistic form triggers interpretation, rather than conveying information [directly]” 28

Meaning and background in conversation Searle: – "the notion of literal meaning of the sentence only has application relative to a set of background assumptions." "Background is the space of possibilities that allows us to listen to both what is spoken and what is unspoken." 29

Discussion: Background in search Find a partner or two and discuss: When you use a search engine – It what ways is it like a conversation? – If we suppose it is like a conversation, what are some relevant feature of the background? 30

Cooperative principles Maxims of quantity Maxims of quality Maxim of relevance Maxims of manner 31

In Information Studies Categories have a special role in systems for information organization. – Explicit classification systems DDC, LC Taxonomy development – Implicit classification IR Relevance – Document genres and their types of content objects and structure 32

Implicit classification in IR Suppose an IR system returns a document in a set of search results – The system has used some features of the document to classify the document as relevant The primary metrics for IR are: – precision: the fraction of retrieved documents that are actually relevant – recall: the fraction of actually relevant documents that are retrieved – NB: these two definitions rely on an implicit binary (relevant/not) classification of all documents in the space 33

Brute vs institutional facts "Brute facts are similar to the largely physical sense data which we call 'facts' in the natural sciences" "... according to Searle,... meaning in language is based on institutional facts, not brute facts." 34

Meaning in IR Blair: – IR systems operate on the basis of 'brute facts' about documents. But: – "The meaning of a document is underdetermined by the brute facts of the document" 35

Explicit Classification: Taxonomy Controlled vocabularies applied (by and large) in commercial applications. – applied to products themselves, instead of the subjects info resources are about – used to structure search result display – and to guide browsing – see, well, most e-commerce sites e.g. Zappo’sZappo’s 36

Explicit classification Library subject classification – Assigning subject categories is a major element of cataloging – Categories are provided by an external authority and applied by local experts List of Dewey Decimal classes – Libraries arrange books physically based on their classifications. 37

Explicit classification Thesaurus (for indexing and retrieval) – A controlled vocabulary consisting of a set of terms a set of hierarchical relationships between terms – e.g. BT, NT, RT a set of rules on applying the vocabulary to documents – e.g. term definitions and usage notes – e.g. NLM’s MeSH (Medical Subject Headings)Medical Subject Headings 38

Controlled vocabularies, generally “an artificial language that maps users’ vocabulary to a standardized vocabulary and to bring like information together” in service of: “The essential and defining objective of a system for organizing information is to bring essentially like information together and to differentiate what is not alike.” -- Svenonius 39

Knowledge Organization Systems Classification systems, subject heading vocabularies, and taxonomies are examples of KOSs What are some basic assumptions here? 40

KOS are Linguistic Artifacts Made up of terms Rule of literary warrant – terms should be selected and used as they appear in relevant literature – (what does the above imply about literatures?) Effective design requires knowledge of entry vocabulary 41

Discussion: Principled priniciples and their pals Find a partner or two and discuss: – Do the cooperative principles seem to capture anything relevant about our experiences with information systems? With a search engine? In creating descriptive metadata? The cooperative principles: – Maxims of quantity » say as much as you need to, not more – Maxims of quality » say what you believe to be true and have evidence for – Maxim of relevance » be relevant – Maxims of manner » be clear, umambiguous, brief, and orderly – Do the cooperative prinicples map to any other principles we've discussed in this class? Hint, think back to week

Language, thought and information 43