Dynamic Foraging Model for Human Behavior on the internet (working title)

Bjarne Berg

2

Agenda

Introduction and Background

Optimal Foraging Theory (OFT)

Foraging Models

Economic perspective (EMH and REH)

Human Factors

Proposed Framework

Question and Answers

3

Background

Despite extensive research in the human evolution since 1854 when Charles Darwin published his thesis on the Origin of the Species, the motivation and the behavior associated with foraging and thereby the natural selection through the survival of the best foragers, was not well researched for over one hundred years.

This changed in 1966 when researchers such as Emlem published his work on the foraging behavior of birds and by the publication the same year of MacArthur & Pianka’s work on the individual’s selection process of foraging areas. Over the next thirty years this research gave rise to a large field known as Optimal Foraging Theory (OFT) that has been the foundation in a variety of biological and zoology studies.

Only in the last ten years OFT has been extended into the field of information technology and search algorithms (Sugawara and Watanabe, 2002; Pui and Huosheng, 2002).

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Background

At the same time, there has been an increased interest in the last decade of extending OFT into a better understanding of human behavior on the internet through intelligent foraging agents (Jiming et. al., 2004) and through extensions to social behaviors of foraging agents (Andrews, 2007).

Most of this research has focused on optimizing the algorithms of robots or intelligent agents that can, on behalf of the human, scan vast amounts of information to find specific items.

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Agenda

Introduction and Background

Optimal Foraging Theory (OFT)

Foraging Models

Economic perspective (EMH and REH)

Human Factors

Proposed Framework

Question and Answers

6

The Optimal Foraging Theory (OFT)

In 1966 the field known as Optimal Foraging Theory (OFT) was established through the publication of Emlen’s article on foraging behavior of birds and by MacArthur & Pianka’s work on optimization models the same year.

In general, the models established over the next ten years focused on four core areas that became known as elements of a micro-ecological theory. These areas include

1) What to eat (optimal diet). 2) Where to eat (optimal patch choice). 3) Optimal allocation to each patch (time). 4) Optimal patterns and speed of movements.

Combined as a whole, the micro-ecological theory forms the platform for macro-ecological theory which has far reaching implications

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The Optimal Foraging Theory (OFT)

Natural Selection – The optimal should already be here

Cost- Benefit and minimal benefit requirements

Optimal Patch Choice (OPC)– scholastic models (bird’s patch selection)

Committed exclusions and logical progressions

Sub-optimal foraging – social and cultural constraints

Compression Hypothesis - as the number of competing species increase, a reduction in the patches used occur & the range of items consumed remains constant or only slightly increase .

Specialization – Koala Bears (increased food abundance leads to greater food preference)

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Agenda

Introduction and Background

Optimal Foraging Theory (OFT)

Foraging Models

Economic perspective (EMH and REH)

Human Factors

Proposed Framework

Question and Answers

9

Foraging Models

Optimal Diet Theory (ODT) - also includes advanced mechanisms for gradual shifts in item acquisitions when preferable items (high net benefit) exists or becomes more abundant.

Optimal Time Allocation (OTA) and Marginal Value Theorem (Chernov, 1976),

and Surrender Time

Evolutionary foraging algorithmsThe simplest approach to account for the dynamically changing environment has been to introduce uncertainty/variability into the approach and rebuild the new optimal search patterns and speed of movements each time a foraging event on a patch, or set of patches, are completed (Yang & Yao, 2005). This was a focus area in the OFT research field in the late 1990s and 00s. The number of recent models proposed using this approach are numerous (Branke, 2002; Jin & Branke, 2005; Tin´os & Yang, 2005).

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Evolutionary Foraging Algorithms (EA)

1. Bacterial foraging algorithms (BFA) and Dynamic BFA (DBFA)

2. Group foraging theory and diversity in Evolutionary algorithms

3. Dynamic and Memory enhanced foraging algorithms (E. Coli)

4. Thermodynamical Genetic Algorithm (TDGA)

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Agenda

Introduction and Background

Optimal Foraging Theory (OFT)

Foraging Models

Economic perspective (EMH and REH)

Human Factors

Proposed Framework

Question and Answers

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EMH and REH

1. Efficient Market Hypothesis

2. Rational Expectance Hypothesis

3. Price Dispersion and 2-step models

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Agenda

Introduction and Background

Optimal Foraging Theory (OFT)

Foraging Models

Economic perspective (EMH and REH)

Human Factors

Proposed Framework

Question and Answers

14

Human Factors

Technology

Basic Technology• Input, output devices• Interaction styles• End-user computing• Org. computing

Advanced Technology• Information visualization• Perceptual/attentive/embodied/

multi-modal/portable/wearable/ implant/personalization

• Persuasive computing• Affective computing

Task / job• Task goals• Task character• Task complexity

Human

Demographics• Gender, age, culture• Comp. experience• Education

Cognition• Cognitive style• Perception• Attention• Memory• Knowledge• Learning• Error• Distributed cognition

Physical/Motor• Motor control• Comfort

Emotion & Motivation• Affectivity• Affective state• Mood/feeling• Emotion• Intrinsic motivation• Extrinsic motivation

Context

Global Context• National culture• Norms• Universal accessibility

Social Context• Privacy•Trust• Ethics• Norms

Org. Context• Org. goals• Org. culture & norms• Policy & procedures• Management support

Group Context• Group goals• Group norms

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Source: Zhang and Li Review of Intellectual Development of HCI Research, 2005 (13 yrs of articles in 7 top journal – 348 articles)

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Agenda

Introduction and Background

Optimal Foraging Theory (OFT)

Foraging Models

Economic perspective (EMH and REH)

Human Factors

Proposed Framework

Question and Answers

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Constructs

The task of the seller is to minimize the consumer surplus, while the task of the consumer is to maximize it. It is important to note that if there are no consumer surplus, the sale cannot occur (consumers would be unwilling to proceed).

Therefore some consumer surplus has to exist, however marginal. In a foraging model an implicit equilibrium should exists between the consumer price, the foraging costs and the foraging surplus on one side and the optimal (best price available) and the incremental foraging costs of locating this best price.

FCFCOPTSFCCP

Or simplified: FCOPTSCP

CP = Cost of item (paid) FC = Foraging costs S = Foraging surplus OPT = Optimal price available (all patches) ∆FC = Additional foraging costs required to locate optimal price

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Constructs

FCCPFCOPTS

FCFCOPTSFCCP

CP = Cost of item (paid) FC = Foraging costs S = Foraging surplus OPT = Optimal price available (all patches) ∆FC = Additional foraging costs required to locate optimal price

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Time Constructs

ID Variable Definition Calculation Example

TA Time to Access

The time it takes before the patch becomes accessible

Measured as time from last action until the site is available

Load time of www.delta.com airline web site

TO Time to Orient

Time it takes from entering a patch to become informed of its purpose and content

Measured from first availability of the site to the next action is undertaken

Time from the web site is loaded until customer undertakes an action

TE Time Enter

The time it takes to enter all the required search criteria to search products or services at a patch.

Measured as time from beginning entering a search at a patch until action is submitted.

Time it takes to enter a search for a flight between two cities at a given day and for a coach ticket.

TF Time to Find

Time to execute search at a patch

Measured from the search action is submitted until the complete set of options are available

Time it takes for Delta's web site to execute the search and present the results (i.e. 10 possible flights).

TR Time to Review

Time it takes to review the items available at a patch after search has been completed.

Measured from the time a result set has been presented until next non review action is taken

Time it takes a customer to review the 10 flights and pick the best option, try another search, or leave the website.

TZ Time to Acquire

Time it takes to take possession of an item

Measured as the time an item has been identified as the solution, until ownership has transferred

The time it takes to select the flight, enter the passenger name, credit card and other data to the purchase confirmation is received.

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Foraging Costs and Incremental Foraging Costs

p

iiiii tztstotaEFC

1

)(

E = cost per unit of time p = number of patches accessed ta = Time to access patch to = Time to orient at patch ts = Time to search tz = Time to acquire item

p

piiiii tztstotaEFC )(

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Foraging Search Costs

xq

jjxxx

s

x

trtftets1

,1

)(

s = Number of searches at a patch te = Time to enter search tf = Time to find (execute search) q = Number of items returned for review tr = Time to review each item

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Overall model (work in progress)

n

kk

p

i

s

x

q

jjxikxikxikikikkkk tztrtftetotaECPFCOPTS

k ik xik

1 1 1 1,,,,,,,,,

, ,,

Experiment identifier

(id)

Survey number

(no)

Optimal price

(OPT )

Price paid (CP)

Patch number

(p)

Patch name (url)

Patch departure

(buy/surrender)

Best price located

patch/search(bqs)

Time to access

(ta)

Time to orient (to)

Search number

(s)

Time to enter (te)

Time to search

(tf)

Number of items

reviewed(q)

Total time to review

S(tr)

Average time to review

(mean tr = S(tr)/q)

Time to acquire

(tz)

No Nm Cd No

1 13 $297 $397 1 delta.com s $384 11 5 1 14 23 22 128 5.82

1 delta.com s $469 11 5 2 13 25 26 105 4.04

1 delta.com s $498 11 5 3 10 26 17 159 5.47

2 Usair.com s $440 8 14 1 16 17 135 139 1.03

2 Usair.com s $635 8 14 2 15 19 122 128 1.05

2 Usair.com s $402 8 14 3 16 19 164 240 0.24

3 Orbiz.com b $397 9 13 1 9 14 14 131 9.36 189

2 13 $165 $165 1 hertz.com s $171 15 5 1 13 22 21 102 4.85

1 hertz.com s $178 15 5 2 12 24 25 84 3.37

2 avis.com s $171 8 13 1 10 25 16 74 4.56

2 avis.com s $209 8 13 2 15 9 130 111 0.86

2 avis.com s $168 8 13 3 14 9 117 102 0.87

3 national.com s $211 9 6 1 15 10 157 32 0.20

3 national.com b $165 9 6 2 9 6 6 65 10.83 206

Seconds SecondsNo AmtAmt

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Example - calculations

Experiment identifier

(id)

Survey number

(no)

Optimal price

(OPT )

Price paid (CP)

Foraging surplus

(s )

Patch number

(p)

Patch name (url)

Patch departure

(buy/surrender)

Surrender time

(seconds)

Incremental foraging

time( ft)

Cumulative foraging

timeS(ftp,s)

Incremental foraging

costs (FC)

Cumulative foraging

costs S(FC)

Best price located

patch/search(bqs)

Incremental foraging surplus

s

No Nm Cd

1 13 $297 $397 -$112 1 delta.com s 181 181 $1.51 $1.51 $384 -$85.5

1 delta.com s 143 324 $1.19 $2.70 $469 -$86.2

1 delta.com s 519 195 519 $1.63 $4.33 $498 -$30.6

2 Usair.com s 172 691 $1.43 $5.76 $440 $56.6

2 Usair.com s 162 853 $1.35 $7.11 $635 -$196.4

2 Usair.com s 609 275 1128 $2.29 $9.40 $402 $230.7

3 Orbiz.com b - 154 1282 $1.28 $10.68 $397 $3.7

2 13 $165 $165 -$8 1 hertz.com s 158 158 $1.31 $1.31 $171 $127.3

1 hertz.com s 278 120 278 $1.00 $2.32 $178 -$8.0

2 avis.com s 109 387 $.91 $3.23 $171 $6.1

2 avis.com s 136 523 $1.13 $4.36 $209 -$39.1

2 avis.com s 126 649 $1.05 $5.40 $168 $40.0

3 national.com s 428 57 706 $.48 $5.88 $211 -$43.5

3 national.com b - 80 786 $.66 $6.55 $165 $45.3

No Seconds AmtAmt

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Some hypothesis

HYPOTHESIS 1: Surrender events increases foraging surplus of participants

(surrender benefits) in electronic commerce.

HYPOTHESIS 2: As the number of available e-commerce sites for a given

(specialization) product increases, usage consolidates to a few sites.

HYPOTHESIS 3: A high number of items returned in a given search has a

(information overload) negative influence on the foraging surplus realized by

actors in an e-commerce marketplace and the impact is not

uniform for all participants.

HYPOTHESIS 4: A negative relationship exists between foraging surplus and

(item availability) a low number of items returned by a search.

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Some hypothesis

HYPOTHESIS 5: The process of site exhaustion (SE) reduces radical changes

(site exhaustion) in patch choices and is inversely related to previous

experience.

HYPOTHESIS 6a: Actors that exhibits a moderate propensity to explore

(exploration) increase their foraging surplus.

HYPOTHESIS 6b: A high propensity to explore is negatively related to

(exploration) foraging surplus (s).

HYPOTHESIS 6c: Age is a factor in the actor’s propensity to explore.

(age - exploration)

HYPOTHESIS 6d: The propensity to explore is directly related to previous

(experience - exploration) experience.

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Your Turn!

How to contact me:Bjarne Berg

bergb@lr.edu