preference reversals induced by screening: the biasing effects of a two-stage decision process...

Preference Reversals Induced by Screening:

The Biasing Effects of a Two-Stage Decision Process

Amitav Chakravarti, New York UniversityChris Janiszewski, University of FloridaGülden Ülkümen, New York University

2

Screening Is Beneficial

• There is ample evidence for two-stage decision process (e.g., Beach and Mitchell 1987; Bettman and Park 1980; Payne 1976)

• There is general agreement that prechoice screening is beneficial (e.g., Alba et al. 1997; Haubl and Trifts 1999; Lynch and Ariely 2000; Roberts and Nedungadi 1995)

– Reduces information overload

– Facilitates choice of the optimal alternative

• It is assumed that prechoice screening does not have any detrimental consequences. Why?

3

Two-Stage Process is Used in Complex Information Environments

BRANDS

A B C D E F

Attribute 1 Low Low High High High High

Attribute 2 High Low High High High Low

Attribute 3 Low Low Low Medium High High

Attribute 4 High Low Medium Low High Medium

Attribute 5 Medium High High High Medium Low

Attribute 6 Medium Low High High High Medium

4

Phased Decision Making: Stage 1a

BRANDS

A B C D E F


Attribute 2

Attribute 3

Attribute 4

Attribute 5

Attribute 6

5

Phased Decision Making: Stage 1b

BRANDS

A B C D E F


Attribute 2 High High High Low

Attribute 3

Attribute 4

Attribute 5

Attribute 6

6

Phased Decision Making: Stage 2

BRANDS

A B C D E F


Attribute 2 High High High Low

Attribute 3 Low Medium High

Attribute 4 Medium Low High

Attribute 5 High High Medium

Attribute 6 High High High

7

Can Screening Be Detrimental?

• Yes, if Stage 1 (prescreening) information is differentiating

• AND if people choose to deemphasize the prescreening information

• AND prescreening and postscreening information are not positively correlated.

A B C D E F

Attribute 1 Low Low Excellent High Excellent High

Attribute 2 Excellent High High Low

Attribute 3 Low Medium High

Attribute 4 Medium Low High

A B C D E F

Attribute 1 Low Low Excellent High Excellent High

Attribute 2 Excellent High High Low

8

Why Might People Deemphasize Prescreening Information?

• Explanation 1: People may not shift to a compensatory strategy in Stage 2. – Reconsidering prescreening information requires effort (Wright and

Barbour 1977).

• Explanation 2: People may shift to a compensatory strategy in Stage 2, but may ignore or deemphasize prescreening information. – The prescreening information has been “used” already (van Zee,

Paluchowski, and Beach 1992).

• Explanation 3: People may shift to a compensatory strategy in Stage 2, but the act of screening may alter perceptions of prescreening information. – The literature on perceptual categorization suggests the act of

categorization makes categorized items appear more similar (Goldstone, Lippa, and Shiffrin 2001).

9

Study 1

• 120 participants chose between six microwave popcorn brands (A, B, C, D, E, F)

• Each brand described by six attributes

– Four prescreening attributes

– Two postscreening attributes

http://images.google.com/imgres?imgurl=http://coloringbookfun.com/food/images/POPCORN.gif&imgrefurl=http://coloringbookfun.com/food/imagepages/image96.htm&h=655&w=600&sz=14&tbnid=Y0CvxDklevsJ:&tbnh=135&tbnw=124&start=39&prev=/images%3Fq%3Dpopcorn%26start%3D20%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DN

10

Study 1: Stimulus Set Properties

Attribute Brand A Brand C Brand E Brand B Brand D Brand F

#1 Common Low cost per serving

Low cost per serving





#2 Common Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Rank

#3 Alignable

SampleCrunchiness lasts 3.5 hours

Crunchiness lasts 3 hours

Crunchiness lasts 2.5 hours



Crunchiness lasts 1 hour

Rank

#4 Alignable

SampleCalories equal to less than a slice of bread

Calories equal to a slice of bread

Calories equal to two slices of bread

Calories equal to a pinch of sugar

Calories equal to a spoon of sugar

Calories equal to two spoons of sugar

Rank

#5 Nonalingable

Sample

Not tough Very crispy and easy to swallow

Few kernels left unpopped

Tastes a bit sweet

Slightly low in corn and grain flavor

Has some citric acid

Rank

#6 Nonalingable

Sample

With waterproof wrapping

Not likely to burn

Does not stick in teeth

Comes in a colorful wrapping

Requires a microwave bowl

Medium size kernels

PrescreeningAttributes

PostscreeningAttributes


11

Study 1: Stimulus Set Properties

Attribute Brand A Brand C Brand E Brand B Brand D Brand F








Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Rank

#3 Alignable

Sample

1







Rank

#4 Alignable

Sample

2

Calories equal to less than a slice of bread






Rank

#5 Nonalingable

Sample

7 5 3 9 11 13Not tough Very crispy

and easy to swallow


Tastes a bit sweet



Rank

#6 Nonalingable

Sample

8 6 4 10 12 14With waterproof wrapping

Not likely to burn




Medium size kernels

PrescreeningAttributes-Most Influential-A > C > E

PostscreeningAttributes-Less Influential-A < C < E

>

>

>

>

<

< <

<

> > >

> > >


12

Study 1 Design

• Three between-subject groups.

– Control Group 1: Free Choice Group

– Control Group 2: Partitioned Choice Group

– Treatment Group: Screening Group

13

Final Choice StageScreening Stage

Study 1: Procedures

Choose one brand

All information(6 brands, 6 attributes)

Rank Attributes

Free Choice Group

Rank Attributes

Shortlist 3 brands

Screening information(6 brands, 4 attributes)

Choose one brand


Screening Group

Rank Attributes

Partitioned Choice Group

Review information

Screening information(6 brands, 4 attributes)

Choose one brand


14

Study 1: All Groups

15

Study 1: Screening Group

16

Study 1: Screening Group

17

Study 1: Partitioned Choice Group

18

Study 1: Partitioned Choice Group

19

Study 1: Free Choice Group

20

Study 1: Choice Shares

59% 61%

35%

27%

38%

27%23%

5%10%

0%

25%

50%

75%

Free Choice Partitioned Choice Screening

A C E A C E A C E

21

Screening Effect

• Participants who did not screen preferred the brand that performed best on the most important attributes (Brand A).

• Screening shifted market share to the brand that performed best on postscreening attributes (Brand E)

• What is the source of the screening effect?

22

Study 2: Source of Screening Effect


Barbour 1977).


Paluchowski, and Beach 1992).

• Explanation 3: People may shift to a compensatory strategy in Stage 2, but the act of screening may alter perceptions of prescreening information. – The literature on perceptual categorization suggests categorization

makes categorized items appear more similar (Goldstone, Lippa, and Shiffrin 2001).

23

Study 2: Key Manipulation

Vary the hedonic dispersion of the postscreening information.

• Explanation 1 (continued noncompensatory processing):

– No influence of increases hedonic dispersion.

– If the screening effect is a consequence of the continued use of a noncompensatory process at Stage 2, then increasing the advantage of E > A should not matter.

• Explanation 2 (deemphasize prescreening information):

– Screening advantage increases with increased dispersion.

– Postscreeing information receives more weight.

24

Study 2: Low Hedonic DispersionAttribute Brand A Brand C Brand E Brand B Brand D Brand F








Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Rank

#3 Alignable

Sample

1







Rank

#4 Alignable

Sample

2







Rank

#5 Nonalingable

Sample


and easy to swallow


Tastes a bit sweet



Rank

#6 Nonalingable

Sample


Not likely to burn




Medium size kernels

25

Study 2: High Hedonic DispersionAttribute Brand A Brand C Brand E Brand B Brand D Brand F








Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Low level of sodium

Rank

#3 Alignable

Sample

1







Rank

#4 Alignable

Sample

2







Rank

#5 Nonalingable

Sample


and easy to swallow


Tastes a bit sweet



Rank

#6 Nonalingable

Sample


Not likely to burn




Medium size kernels

26

Study 2: Aggregate Choice Shares

58%53%

29%

22%

45%

22%21%18%

14%

0%

25%

50%

75%

Free Choice Partitioned Choice Screening

A C E

A C EA C E A C E

27


58%

37%

25%

19%

35%

13%

0%

25%

50%

75%

Free Choice &Partitioned Choice

Screening

51%

19% 19%

24%

58%

20%

Free Choice &Partitioned Choice

Screening

Low Hedonic Dispersion High Hedonic Dispersion

[58.3-13.1]-[36.8-35] = 43.4% [51.4-20]-[19.4-58.2] = 70.2%

A C EA C E A C E A C E

28

Study 2: Results

• The size of the screening effect increases with increased variation in postscreening attribute desirability

• People are indeed placing more emphasis on the postscreening information.

29

Why Might People Deemphasize Prescreening Information?


Barbour 1977).


Paluchowski, and Beack 1992).

• Explanation 3: People may shift to a compensatory strategy in Stage 2, but the act of screening may alter perceptions of prescreening information. – The literature on perceptual categorization suggests categorization

makes categorized items appear more similar (Goldstone, Lippa, and Shiffrin 2001).

30

Two Goals of Study 3

• Further Investigate Explanation 2: Why do people ignore or deemphasize prescreening information.

– Reason 1: The prescreening information has been considered at Stage 1.

– Reason 2: The prescreening information has been used to select a set of options at Stage 1.

• Study 3 adds a passive screening condition: People rate alternatives and then an agent (computer) screens alternatives using these ratings.

– If Reason 1 (consideration) is correct, passive screening should result in a screening effect.

– If Reason 2 (using to select) is correct, passive screening should NOT result in a screening effect. People are not using the prescreening information to actively select a consideration set.

31

Two Goals of Study 3

• Further Investigate Explanation 3: The act of screening may alter perceptions of prescreening information.

– Reason 3: Categorizing items makes within-category items appear to be more similar.

• Study 3 adds a condition that allows us to assess the influence of screening on the perception of prescreening information: People are asked to screen and rate alternatives. – If Reason 3 (increased homogeneity of prescreening information) is

correct, the ratings of retained alternatives should be more homogeneous after screening than before screening.

32

Final Choice StageFirst Stage

Study 3: Procedures

Rate all brandsScreening information(6 brands, 4 attributes)

Rating Group

Choose one of three highest rated brands

See all information(6 brands, 6 attributes)

Shortlist 3 brandsScreening information(6 brands, 4 attributes)

Screening & Rating

Group

Choose one brandSee all information

(6 brands, 6 attributes)

Rate all brandsScreening information(6 brands, 4 attributes)



Choice Group


Review information Screening information(6 brands, 4 attributes)






Screening Group

33


63%61%

41%

68%

56%

31%

17%

24%19%19%20%

73%

20%

14%13%

0%

25%

50%

75%

Free Choice PartitionedChoice

Screening Rating Screening &Rating

A C EA C E A C E A C E A C E

34


63%61%

41%

68%

56%

31%

17%

24%19%19%20%

7%

19%

14%13%

0%

25%

50%

75%




35

First Conclusion of Study 3

• Why do people ignore or deemphasize prescreening information?



36

Study 3: Ratings Homogeneity

• Computed the mean variance of the ratings of the consideration set brands in the

– Rating Group = 3.04

– Screening and Rating Group = 1.61

– Significantly different (F(1, 80) = 7.32, p < .05)

37

Second Conclusion of Study 3

• Further Investigate Explanation 3: The act of screening may alter perceptions of prescreening information.

– Reason 3: Categorizing items makes within-category items appear to be more similar.

38


63%61%

41%

68%

56%

31%

17%

24%19%19%20%

7%

20%

14%13%

0%

25%

50%

75%




39

Third Conclusion of Study 3

• Why do people ignore or deemphasize prescreening information?



– Solution: People can be encouraged to reconsider used information if it is made salient again, as we did with our rating task (screening and rating condition).

– Implication: Screening influences the perceived homogeneity, and the relative weight, of the prescreening information.

40

Goal of Study 4

• Study 3 shows that active screening alters the perception and use of prescreening information. Why?

– Reason 1: “Active screening” occurs because decision makers use a noncompensatory process in Stage 1. Using the noncompensatory process at Stage 1 encourages a person to both discount prescreening information and see it as more homogeneous.

– Reason 2: “Active screening” occurs because of decision makers categorize (i.e., put alternatives into a consideration set) at Stage 1. Categorizing items makes within-category items appear to be more similar, hence less useful for making a choice.

• Study 4 adds a screen-by-rejection group

– In contrast to the screening group, the screen-by-rejection group excludes alternatives from the choice set.

41

Goal of Study 4

• Study 3 shows that active screening alters the perception and use of prescreening information. Why?

– Reason 1: “Active screening” occurs because decision makers use a noncompensatory process in Stage 1. Using the noncompensatory process at Stage 1 encourages a person to both discount prescreening information and see it as more homogeneous. YES

– Reason 2: “Active screening” occurs because of decision makers categorize (i.e., put alternatives into a consideration set) at Stage 1. Categorizing items makes within-category items appear to be more similar, hence less useful for making a choice. NO

• Study 4 adds a screen-by-rejection group. Screening Effect?

– In contrast to the screening group, the screen-by-rejection group excludes alternatives from the choice set.

42

Final Choice StageFirst Stage

Study 4: Procedures

Reject 3 brandsScreening information(6 brands, 4 attributes)

Screen-by-Rejection

Group





Choice Group


Review information Screening information(6 brands, 4 attributes)






Screening Group

43

Study 4: Procedure

• Screening Instruction.

– After you have gone through these descriptions to your satisfaction, as a first step towards picking a brand of your choice, please shortlist three brands that you would consider more seriously for purchase. We will provide you with more information on these three brands on the next screen. Please do not make up your mind about your final choice yet; simply select (i.e., shortlist) three brands that you think warrant further attention by clicking on the appropriate buttons below.”

• Screen-by-rejection Instruction

– “After you have gone through these descriptions to your satisfaction, as a first step towards picking a brand of your choice, please reject three brands that you would not consider more seriously for purchase. We will provide you with more information on the three surviving brands on the next screen. Please do not make up your mind about your final choice yet; simply reject (i.e., throw away) three brands that you think do not warrant further attention by clicking on the appropriate buttons below.”.

44


60%56%

39%

55%

30%

23%21%22%

37%

16%13%

3%

0%

25%

50%

75%


Screening Screen-by-Rejection


45

Conclusion of Study 4

• Why does active screening alter the perception and use of prescreening information.

– Reason 1: “Active screening” occurs because decision makers use a noncompensatory process in Stage 1. Using the noncompensatory process at Stage 1 encourages a person to both discount prescreening information and see it as more homogeneous.

– Reason 2: “Active screening” occurs because of decision makers categorize (i.e., put alternatives into a consideration set) at Stage 1. Categorizing items makes within-category items appear to be more similar, hence less useful for making a choice.

46

Summary of Studies

Naïve Expectation Result

Study 1 & 2Does screening effect occcur when Stage two processing is noncompensatory? It Must N/A

compensatory? No Yes

Study 3Does the screening effect depend changes in the ___ of prescreening information at Stage two choice? weight Yes Yes

value No Yes

Study 3Does the screening effect depend on ___ prescreening information in Stage one ? considering Yes No

classifying via No Yes

Study 4 Does the screening effect depend on the Stage one process (noncompenatory)? Yes No

outcome (CS formation)? No Yes

47

Conclusions

• Screening can alter decision making when prescreening and postscreening information is negatively correlated.

• Screening appears to influence the perceived homogeneity of prescreening information and the relative importance of this information (as compared to postscreening information).

• Inclusionary, as opposed to exclusionary, screening is responsible for the screening effect.

48

General Discussion

• Implications of creating a consideration set via screening (and increasing the perceived homogeneity of prescreening attributes)– Increased price sensitivity if price is not a screening attribute (e.g.,

Diehl et al. 2003).

– Delay decision to purchase (e.g., Dhar 1997).

– Desire to search for additional, less important information (e.g., Moorthy, Ratchford, and Talukdar).

• Issues– Why does classification reduce differentiation on the classification

variables?

– When do people engage in inclusionary, as opposed to exclusionary, screening?

preference reversals induced by screening: the biasing effects of a two-stage decision process...

Documents