The Availability Heuristic Psychology 466: Judgment & Decision Making Instructor: John Miyamoto 10/15/2015: Lecture 03-2 Note: This Powerpoint presentation

The Availability Heuristic

Psychology 466: Judgment & Decision Making

Instructor: John Miyamoto 10/15/2015: Lecture 03-2

Note: This Powerpoint presentation may contain macros that I wrote to help me create the slides. The macros aren’t needed to view the slides. You can disable or delete the macros without any change to the presentation.

Outline

• Review definition of the availability heuristic

• Availability biases judgment of likelihood when memories differ in ease of encoding or retrieval (or both).

• Egocentric bias and solo status - consequences of availability

• Distinguishing ease of recall from number of memories recalledas causes of availability bias.

• Hindsight bias and other related biases.

Psych 466, Miyamoto, Aut '15 2Definition of Availability and Diagram of Memory Influence on Availability

Psych 466, Miyamoto, Aut '15 3

Why Is the Availability Heuristic a Reasonable Procedure?

• In general, frequently encountered events are easier to recall.

• The availability heuristic exploits the converse relationship:

Events that are easy to recall are thought to occur frequently.

Possibilities that are easy to imagine seem more likely.

Frequency of Experience

Other Factors

Availabilityof Memory

Learning


Judged Frequency of Experience

Judgment of Likelihood

Same Slide - Emphasis on Learning








Other Factors


Learning




Same Slide - Emphasis on Judgment of Likelihood








Other Factors


Learning




Same Slide - No Emphasis








Other Factors


Learning




Standard Memory Model (Diagram)

Influence of Availability


Standard Memory Model

• Availability biases are the consequence of non-frequency factors that

influence memory encoding, retrieval, and

mental construction.

ExternalStimulus

SensoryRegisters

VisualAuditoryHaptic

GustatoryOlfactory

Working MemoryControl Processes

RehearsalCoding

Symbol and Image Manipulation

Information Processing Strategies

Long-Term Memory

Memory TracesEpisodicSemantic

PerceptualProcedural

Cognitive ToolboxJudgment StrategiesDecision Strategies

Heuristics

encoding

retrieval

control processes

List Different Types of Availability Bias


Different Types of Availability Bias

• Biased exposure to events. Sampling bias

• Encoding and retrieval biases: Solo status and egocentric bias.

• Biases due to differential ease of retrieval or mental constructions

Examples of Availability Bias Due to Biased Exposure


Availability Bias Due to Sampling Bias or Biased Exposure

• In 2002, which is more likely, death in a motor vehicle accident or death

from influenza or pneumonia?o 2002 motor vehicle deaths = 15.3 per 100,000;

Influenza/pneumonia deaths = 22.8 per 100,000o TV coverage obviously emphasizes dramatic events and underrepresents

undramatic events. E.g., more Americans die from diabetes and stomach cancer than from homicide and car accidents by a ratio of nearly 2:1.

• Clinical belief that child sexual molestors do not stop on their own. People

who are caught are much more likely to be serial child molestors than a one-

time child molestor.

• Telling subjects that they are being given a biased sample

of information does not eliminate effect of sample bias.

Hamill, Nisbett & Wilson Study – Insensitivity to Sampling Bias


Remarks on Insensitivity to Sampling Bias or Exposure Bias

Things we all know:o TV ads do not give an accurate picture of the value of products.o Political spin doctors are trying to manipulate our beliefs.o TV news is not a representative sampling of events.o The portrayal of men/women, black/whites, rich/poor, gay/straight, on TV is not a

representative presentation of these groups.o Our own experiences are not typical of everybody’s experience.o Etc.

• We know that these information sources are biased, but can we correct for

these biases or take them into account when forming beliefs? Doubtful.

• Availability promotes influence of biased information.

Continuation of the Remarks on this Slide


Remarks on Insensitivity to Sampling Bias or Exposure Bias

• Insensitivity to sampling bias (exposure bias) is only partly

a cognitive bias. o The world feeds us biased information, ....o .... but we have difficulty taking this into account.

• Note that these results can result from a combination of availability bias and

anchoring and adjustment bias.

Return to List of Different Types of Availability Bias


Different Types of Availability Biases

Biased exposure to events. Sampling bias

• Encoding and retrieval biases: Egocentric bias & solo status.

• Biases due to differential ease of mental constructions

Encoding & Retrieval Biases – Famous Names x Men/Women

Availability Bias Due to Ease of Encoding or Retrieval


Condition I:Famous Male

Non-Famous Female

Bill ClintonTom Hanks

Michael Jordan........

Mary BrooksAndrea ForbusLeanne Faris

.......

Condition II:Famous Female

Non-Famous Male

William TowersMurray JencksLionel Worley

........

Hilary ClintonMarilyn Monroe

Sarah Palin........

• Condition I: Subjects saw a list of names, one at a time, that

mixed 18 famous males with 19 non-famous females.

• Question: Did you see more men or more women?

Same Slide with Emphasis on Condition II




Non-Famous Female




.......


Non-Famous Male


........


Sarah Palin........

• Condition II: Subjects saw a list of names, one at a time, that

mixed 19 non-famous males with 18 famous females.

• Question: Did you see more men or more women?

Results – Why Does This Effect Occur?

• Subjects reported that there were more males if the males were

famous, and more females if the females were famous.

• Why does this happen?




Non-Famous Female




.......


Non-Famous Male


........


Sarah Palin........

Standard Memory Model – Why Does this Result Occur?


Standard Memory Model

• In terms of the standard memory model, why do subjects think they have seen more names of the sex that is famous?

• Is this relevant to our perceptions of everyday life?

ExternalStimulus

SensoryRegisters


GustatoryOlfactory


RehearsalCoding



Long-Term Memory




Heuristics

encoding

retrieval

control processes

Egocentric Bias


Egocentric Bias

• Egocentric bias: People overrate the proportion of the total work to a

project that they have contributed.

• Ross & Sicoly (1979): Subjects were 37 married couples.

• Working separately, husband and wife rated self and spouse for their work

on 20 activities: o Good Actions: Making breakfast; cleaning dishes; cleaning house; making

important decisions; ... o Bad Actions: Causing arguments between themselves; making the house messy;

irritating spouse; ....

What Is Pattern in Ratings when No Egocentric Bias is Present


How to Measure Egocentric Bias

primarily primarilyhusband wife

• Subjects rated their responsibility on a line as shown above.

Husband's rating measured as distance from the right end;

wife's ratings measures as distance from the left end.

• If husband and wife have accurate perceptions of responsibility,

the sum of their ratings should equal the length of the line.

Example: Husband & Wife Are Consistent with Each Other

Example: Husband & Wife Are Consistent With Each Other

• How often do you wash the dishes?


• If husband and wife are not egocentric, the couple's ratings should sum to +100 as shown here.


I +25 in husband's scoring

I +75 in wife's scoring

+100 total of husband & wife

Example: Husband and Wife are Inconsistent with Each Other

Example: Husband & Wife Are Consistent With Each Other

• How often do you wash the dishes?


• If husband and wife are egocentric, the couple's ratings would sum to +100 as shown here.


I +48 in husband's scoring

I +75 in wife's scoring

+123 total of husband & wife

Results of This Study

• The inconsistent (egocentric) pattern is typical:


• Ratings consistently summed to number greater than +100 across a variety of activities.

• The result holds for both good things (wash the dishes) and bad things (buy unnecessary things).

• General Finding: Excessive attribution to self. Why does this occur? (See next slide)


Results for Egocentric Bias Study

Husband’s Rating + Wife’s Rating > 100

Return to Diagram for Standard Memory Model + Conclusions


Conclusion re Egocentric Bias

• Egocentric bias is probably related to the greater availability

of self-actions than other-actions (actions by someone else).

• Encoding bias? Retrieval bias? Both?

Solo Status

ExternalStimulus

SensoryRegisters


GustatoryOlfactory


RehearsalCoding



Long-Term Memory




Heuristics

encoding

retrieval

control processes


Solo Status

• A person has solo status in a group if he or she is the unique person with

some salient characteristic in the group. o Only woman in a group of men; only man in a group of women.o Only black in a group of whites; only white in a group of blacks.o Only person wearing a bright red shirt.

Experimental Studies of Solo Status


Experimental Studies of Solo Status

• Studies of solo status usually create a group in which

someone has solo status. o Many different ways to create solo status.

• The group engages in a task, e.g., discuss the question, "how can we get a

student with a drinking problem to drink less?"

• After the task, everyone in the group rates everyone else in the group on a

series of attributes.o How much did this person contribute to the discussion? o How often did this person make irrelevant remarks? o How often did this person say something humorous?

Results of Initial Studies on Solo Status


Results on Solo Status

• Initial finding: Over-attribution of causal contributions to a person with

solo status. (Both good and bad.)

• Solo status was created in many different ways with same result.o Only one black among whites; only one woman among men.o Only person wearing red smock among white smocks. Also, lighting.

• Two interpretationso Availability interpretation: It is easier to code the actions of the solo individual

than other individuals. Therefore it is easier to remember that the solo person did specific things than other persons.

o Social dynamic interpretation: A person in solo status behaves in more extreme ways than non-solo people. Therefore he or she gets more extreme attributions.

• How to distinguish between these two interpretations?

Experiment that Distinguishes Btwn Availability & Social Dynamic


Effects of Solo Status Based on Room Arrangements

• One set of subjects (discussants) are arranged in a

triangle facing each other (grey symbols in the

figure).

• A second set of subjects (observers) are arranged

in surrounding positions (green symbols in the

figure).

• Each observer has a good view of one discussant, and a mediocre view of the two other discussants. Different discussants have solo status for different observers.

Finding: The observers make stronger attributions to the discussants who have solo status for the particular observer.

Conclusions re Availability, Encoding & Retrieval


Consequences of the Availability Heuristic

• Stronger attributions to the self than to others. o Easier to encode and retrieve self actions than actions of other.

• Stronger attributions to a solo individual. o Easier to encode and retrieve memories of the solo person's actions. o Both good and bad attributions.

• Anything that makes it easy to encode or retrieve information

can make events seem more typical or more frequent than they are.

• Biased information sources can cause biased judgment even

if we know the information is biased.

Transition to ease of mental construction and fluency as cues to availability

Next: Reasoning “Fluency” and Ease of Retrieval

• Previous examples emphasized influence of other factorson encoding and retrieval.

• Next: Factors that affect reasoning “fluency” andperceived ease of retrieval.

A memory can be available because it feels easy to recall.

Psych 466, Miyamoto, Aut '15 28What Is Ease of Recall?


What is Ease of Recall?

Availability heuristic – events are judged more probable if examples of similar

events are easy to recall or easy to construct mentally (easy to imagine).

What is ease of recall? Two interpretations of "ease of recall":

• Number of Memories: A person is able to remember few or many memories

of a particular kind

• Ease of Recall: The act of recalling memories of a particular type feels

effortful or effortless.

Schwartz Experiment – Number of Memories vs Ease of Recall


Testing Number-of-Memories versus Effort-of-Recall

Schwarz, N., H. Bless, F. Strack, G. Klumpp, H. Rittenauer-Schatka and A. Simons (1991). Ease of retrieval as information: Another

look at the availability heuristic. Journal of Personality and Social Psychology, 61, 195-202.

• Basic idea: o Condition 6 M: Describe 6 examples in which you behaved assertively.o Condition 12 M: Describe 12 examples in which you behaved assertively.o After the recall task, all subjects rate themselves for how assertive they are.

• Hypothesis: o Condition 6 M - easy to recall 6 examples of assertive behavior

(low effort). o Condition 12 M - relatively hard to recall 12 example of assertive behavior (high

effort).

• Prediction: Subjects in the 6 M Condition will rate themselves

as more assertive than subjects in the 12 Memories condition.

Why make this prediction?

Schwartz Experiment – Experimental Design


Schwartz et al. (1991)

• 2 x 2 experimental design: o Type of Behavior:

Recall examples of assertive behavior or unassertive behavior.

o Number of Memories: Recall 6 or 12 examples.

• 40 women (German students), random assignment

• Only difference between this description and the previous slide is that real

experiment included a condition where subjects imagined examples of being

unassertive.

• After describing their memories, subjects rated their own assertiveness.

Results of Schwartz et al. (1991)


Schwartz et al. (1991) Results

• Are the results consistent with Schwartz’s hypothesis?

• Effort of recall affects strength of attribution when controlling for number of

examples recalled.

Interpretation: If it feels easy to remember similar events,

these events are more available even if fewer events are recalled.

Manipulating Effort of Recall by Facial Expression


Another Way to Manipulate Effort of Recall

• Fact: Adopting a body posture and facial expression that is consistent with

an emotion facilitates experience of the emotion even if one knows that the

posture and facial expression are not emotional responses. o Furrowed brow (contract corrugator muscles) – associated with efforto Light smile (contract zygomaticus muscle) – associated with feeling of ease

Results of Manipulating Facial Expression During Recall


Results for Facial Expression & Recall of Assertive/Unassertive Behavior

• Subjects recall 6 examples of assertive or unassertive behavior while

adopting a furrowed brow or light smile.

• Light smile + recall assertiveness higher ratings of

assertiveness

Furrowed brow + recall assertiveness lower ratings of

assertiveness

• Light smile + recall unassertiveness lower ratings of

assertiveness

Furrowed brow + recall unassertiveness higher ratings of

assertiveness

Partial Summary re Availability Studies


Partial Summary re Availability Heuristic

Events seem more available when ....

• .... it is easy to recall many similar events; or ......

• .... the retrieval of similar events feels easy to do; or .....

• .... it is easy to construct similar events mentally.

Judgments of event likelihood are biased by the availability

heuristic when factors that are unrelated to event likelihood

influence ease of recall or ease of mental construction. o Note that use of availability doesn't always bias judgment – in many

cases it produces reasonably accurate judgments.

• Next: Cognitive behaviors that are related to availability.

Hindsight Bias


Hindsight Bias

• Hindsight Bias: Once we know the true outcome, we think that before the

outcome occurred, it appeared more probable than it really did.

• Everyday experience supports this idea.

• Example: Today, it seems pretty clear that Obama was a more

effective political campaigner than Hilary Clinton and John

McCain.

Do we think now that it was clear in 2008 that Obama would win?o FYI: Hindsight bias is discussed in Hastie & Dawes, Ch 6, 133 – 137.

Hindsight Bias


Hindsight Bias with General Knowledge Questions

• Fischhoff (1977): Subjects were asked general knowledge questions, e.g.,

What is the capital of Australia?

a) Sydney b) Melbourne c) Canberra d) Brisbane

• Some subjects are told the answers and are asked to give the probability that

they would have gotten it right even if they had not been given the answer.

Others were not told the answers.

• Probability of knowing the answer is much higher for subjects who were told

the answer.

Longitudinal Study of Hindsight Bias


Longitudinal Study of Hindsight Bias

• Fischhoff (1975): Subjects were asked to state how likely were particular

events relating to President Nixon’s historic visit to China in 1972.o E.g., what is the probability that he will meet face to face with Chairman Mao?o E.g., what is the probability that the U.S. and China will propose a mutual

non-agression treaty?o etc.

• Some of these events actually occurred, and others did not.

Results of Longitudinal Study


Results of Longitudinal Study of Hindsight Bias

• Fischhoff (1975): Subjects were asked to state how likely were particular

events relating to President Nixon’s historic visit to China in 1972.

• Later, subjects were asked to state the probability that they had previously

given for these events. The true outcome was known by this time.

• Result: Subjects’ memories were biased towards the actual outcomes – o things that happened had a higher probability in hindsight; o things that did not happen had a lower probability in hindsight.

What Causes Hindsight Bias?


What Causes Hindsight Bias?

• Ask the class – why do they think hindsight bias occurs?

• Self-serving bias? Self-protective bias?

• Availability of causes – after knowing the true outcome,

causes that lead to the known outcome become more salient

and causes that lead to non-occurring outcomes become

less salient or are forgotten.

• In visual hindsight bias, Harley, Carlson & Loftus argued for a fluency

misattribution. (See next slide)

Hidden Object Image

What Do You See in this Image?

• Once you see the object, it becomes harder judge the difficulty in finding the image. Perceptual fluency explanation.

Psych 466, Miyamoto, Aut '15 41Consequences of Hindsight Bias


What Are Consequences of Hindsight Bias?

• Regret and recrimination.

• Persistent reasoning errors.

Difficulty learning from experience (inaccurate self-evaluations).

• Overconfidence.

• Creeping determinism (Fischhoff)

Reasons For & Reasons Against

Thursday, October 15, 2015: The Lecture Ended Here


Effects of Order on Pro & Con Reasons

Condition 1: o First, list as many reasons as you can in favor of X, e.g.,

in favor of making public the names of people who sign petitions for referendums.

o Second, list as many reasons as you can against X, e.g., against making public the names of people who sign petitions for referendums

Condition 2: Same as Condition 1 with the “pro” and “con” conditions in the opposite order.

Result: More pro reasons are given when pro reasons given before con reasons (Condition 1) than when con reasons given before pro reasons (Condition 2).

Planning Fallacy


Planning Fallacy

• Planning Fallacy – the tendency to underestimate the time or difficulty needed

to accomplish a complex task.

• E.g., how long will it take to finish this project?

• E.g., how hard will it be to get everyone to agree on a plan?

• Is the planning fallacy due to the greater availability of reasons

why a plan will succeed than reasons why it will face obstacles?

Conclusions re Availability - END


Availability: Conclusions

• The availability heuristic is a reasonable way to judge the likelihood of

events. It leads to good answers most of the time.

• The availability heuristic produces biased judgments when factors unrelated

to likelihood affect encoding, ease of retrieval or ease of mental

constructions. o Biased exposure or sampling biaso Exceptionally dramatic or "vivid" events. o Conditions, like solo status and an egocentric perspective, can bias

the availability of memories. o Factors that make it feel easier or harder to retrieve memories affect availability

(self monitoring of ease of recall). o Priming and other influences on retrieval can influence mental construction, and

hence, availability.

END

Documents

The Availability Heuristic Psychology 466: Judgment & Decision Making Instructor: John Miyamoto 10/15/2015: Lecture 03-2 Note: This Powerpoint presentation