© Tefko Saracevic 1

What is information?What is information?

Really, what is it?

© Tefko Saracevic 2

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As a phenomenon …

Answer:WE DON’T KNOW!

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As a concept …

Well, we understand it intuitively quite well We have a number of lexical definitions We use it and nobody has to define it for us

it is a y’know concept We easily adapt to various connotations

(differing senses) depending on the context

But formally, in a scientific sense, we really don’t know what information is as a phenomenon,

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As a basic phenomenon

We don’t know what information is any more than we know what is

energy

matter

gravity

life

knowledge Basic phenomena in physics, biology,

philosophy …we don’t know what they are, BUT:

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So how do we study them?

We study their

manifestations

behavior

(or behaviour if you are British)

effects All scholarship, every science does this

e.g. we don’t know what gravity is, but we have physical laws that describe its behavior and effects

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this slide doesn’t have to do with the lecture topic

but I liked the picture, so here it is

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Information treated in various disciplines

physics – basic property as energy, matter

biology – senses neurophysiology – brain processes psychology – behavior, perception cognitive science – cognition telecommunication, computer

science – signals, bits philosophy – knowledge

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Information in information science

Again: intuitively well understood, but formally not well stated Several viewpoints, models emerged

Shannon: source-channel-destination signals not content – not really applicable

Cognitive: changes in cognitive structures content processing & effects

Social: context, situation information seeking, tasks

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Shannon's information theory

Developed a general model for communication systems, and a set of theoretical tools for analyzing such systems, by measuring information in terms of probabilities (numbers)

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Shannon … reducing uncertainty

Defined information in terms of probabilities developed measure of the information we get from

observing the occurrence of an event, BUT ignored any particular features of the event e.g. flipping a fair coin once will give us events h and t

each with probability 1/2, and thus a single flip of a coin gives us - log2(1/2) = 1 bit (Binary digit) of information (whether it comes up h or t)

Information measured in bits is the reduction in uncertainty in the mind of the receiver information (in bits) is the amount of uncertainty a

measure eliminates

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Shannon’s impact

Had great impact in treating of digital information as signals e.g maximizing capacities of

channels; coding Had disappointing impact

(despite many tries) where information is connected with meaning, context, humans, values the ideal to measure information in

human terms is elusive but keep trying …

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Cognitive – basic idea:

K(S) + ΔI = K(S + ΔS) (Brookes)

Information when operating on a knowledge structure produces an effect whereby the knowledge structure is changed

“Information is differences that make a difference” (find who said it!)

Actually, it only states the problem – “unoperational” in information systems involves cognitive, mental events only constructivists rejected it

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Information manifestations (Buckland)

Information as a process what someone knows is changed when informed; “the action of

informing” (similar as Brookes) refers to cognitive changes + process of doing it

Information as knowledge knowledge communicated about x

uncertainty removal a special case refers to that which is being communicated - intangible

Information as a thing data, documents with quality of imparting information - tangible

refers to potential information conveyed from objects

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Information in information science

Three senses (from narrowest to broadest)

1. Information in terms of decision involving little or no cognitive processing - Shannon

signals, bits, straightforward data - computing, telecommunication, economics,

2. Information involving cognitive processing & understanding - Brookes

understanding, matching texts

3. Information also as related to context, situation, problem-at-hand, process – Buckland to some extend

users, use, tasks

For information science (including information retrieval):

third, broadest interpretation necessary

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What is in a book?(for discussion in class)

Cover page of a book:

What is in it?

What is in it?

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A chapte

r in that book

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Here is also a cover page of a book:

What is in it?

What is in it?

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A chapte

r in that book

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Adequacy? None of the theories about

information are adequate to cover fully information as a phenomenon

Each covers a bit or simply describes manifestation

Shannon’s theory is testable, but reduces “information” to signals only

A scientific theory is one that can be refuted – tested for confirmation, rejection (Popper)

- they understood this 1564-1642

1452-1519

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So we went to study

Human information behavior “how people need, seek, manage, give, and use

information in different contexts” (Pettigrew ) many models, theories, studies on a variety of aspects extends to study of web behavior

Bibliometrics “the study, or measurement, of texts and information”

(Norton) many studies and formal statements about structure &

patterns of literatures, citations, authors, journals, texts … Bradford’s law, Lotka’s law

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to be continued …

We cover these in other lectures and courses and two 2005 books cover very nicely the topics of

theories of human information behavior

and

integration of information seeking and information retrieval in context highly recommended

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p.s. there is code in other slides