Content uploaded by Lee Ross
Author content
All content in this area was uploaded by Lee Ross on Jan 13, 2016
Content may be subject to copyright.
Journal of Personality and Social Psycholocy
1977,
Vol 35, No. 11, 817-829
Social Explanation and Social Expectation: Effects of Real and
Hypothetical Explanations on Subjective Likelihood
Lee Ross, Mark R. Lepper, Fritz Strack, and Julia Steinmetz
Stanford University
Subjects in three experiments were induced to explain particular events in the
later lives of clinical patients whose previous case histories they had read, and
they were then asked to estimate the likelihood of the events in question. Each
experiment indicated that the task of identifying potential antecedents to ex-
plain an event increases that event's subjective likelihood This phenomenon was
replicated across a variety of clinical case studies and predicted events and was
evident both under conditions in which subjects initially believed the events they
explained to be authentic, only to learn afterward that no information actually
existed about the later life of the patient, and under conditions in which sub-
jects knew from the outset that their explanations were merely hypothetical.
Implications of these findings for previous investigations dealing with belief
perseverance and the consequences of hindsight perspective are outlined, and
potential boundary conditions of the observed effect are discussed.
Our perceptions of social phenomena—from
automobile accidents to political upheavals,
from academic failures to acts of altruism—are
organized in considerable measure by the
underlying causal connections we detect or
postulate. Attribution theorists, among many
others, have long emphasized the extent to
which causal inferences add coherence to our
perceptions of the entities and events in our
social world. Indeed, several generations of
such theorists have explored both the logical
rules or schemata that may underlie judgments
of social causality and the biases that may
distort such judgments (e.g., deCharms, 1968;
Two of the three experiments described in this article
were previously reported in a paper by Fritz Strack,
Mark R. Lepper, and Lee Ross entitled "Explaining is
Believing: The Effects of Providing a Causal Explana-
tion on the Perceived Probability of an Event's Occur-
rence " This paper was presented at the 56th Annual
Meeting of the Western Psychological Association,
Los Angeles, April 1976. The present research was
supported, in part, by National Institute of Mental
Health Research Grant MH-26736 to Lee Ross and
Mark R. Lepper and by a Harkness Foundation
Fellowship held by Fritz Strack. The authors gratefully
acknowledge helpful comments on the manuscript
and/or research by Robert Abelson, John Carroll,
David Greene, and Richard Nisbett.
Julia Steinmetz is now at the University of Oregon.
Requests for reprints should be sent to Lee Ross,
department of Psychology, Jordan Hall, Stanford
University, Stanford, California 94305.
Heider, 1944, 1958, Jones & Davis, 1965;
Jones etal., 1972; Kelley, 1967,1973; Kruglan-
ski,
1975, Ross, 1977).
Recently, however, Ross, Lepper, and
Hubbard (1975) have suggested that an un-
warranted perseverance of initial beliefs and
impressions may be one cost of man's proclivity
for causal explanation. Briefly, Ross et al.
(1975) reported two studies in which false
feedback concerning performance on a novel
discrimination task (i.e., distinguishing au-
thentic suicide notes from fictitious ones)
continued to influence both the self-perceptions
of the actors and the social perceptions of
observers even after that initial feedback had
been totally discredited through an extensive,
standard debriefing procedure. This persever-
ance effect has since been replicated using a
variety of experimental settings and pro-
cedures for discrediting the evidential basis for
these impressions of information (cf. Lau,
Lepper, & Ross, Note 1; Jennings, Lepper,
Ross,
& Steinmetz, Note 2). For instance, Lau
et al. (Note 1) demonstrated that students'
erroneous impressions concerning their logical
problem-solving abilities (based on their
performance in an initial test situation)
persevered, even after the students learned that
good or poor teaching performance had
virtually guaranteed their original success or
failure. Despite subsequent exposure to alter-
817
818
ROSS,
LEPPER, STRACK, AND STEINMETZ
native teaching methods, these initial beliefs
persisted and influenced students' curriculum
preferences in the classroom several weeks
later.
In discussing the biased attributional pro-
cesses that might underlie such results, Ross
et al. (1975) speculated that perseverance of
initial impressions and expectations might be
due,
in part, to subjects' attempts to explain
the evidence they had encountered. Once an
action, outcome, or personal disposition has
been interpreted as the consequence of known
or even postulated antecedents, Ross et al.
contended, these antecedents may continue to
imply the relevant consequence, even after the
evidence that initially led to this attribution
has been removed or undermined. Consider,
for example, a subject in the Ross et al. study
who attributed her apparent initial success
in discriminating real from fictitious suicide
notes to her empathetic personality and the
insights she gained from the writings of a
novelist who committed suicide. Or, consider
a subject who attributed her apparent initial
failure at this task to her lack of familiarity
with people who might contemplate suicide.
Even after debriefing, these subjects retain a
plausible basis for inferring the likelihood of
the relevant outcome and for drawing corre-
spondent inferences concerning their actual
ability in the discrimination task. Similarly,
observers who identified or inferred personal
characteristics to account for the apparent
initial success or failure of their peers also
retained a basis for perseverance in their social
attributions following debriefing.
In more general terms, Ross et al.'s (1975)
contention is that even the removal of all
evidence that some event ever occurred may
leave a set of salient or highly available (cf.
Tversky & Kahneman, 1973) antecedents
that continue to imply the occurrence of that
event. With such a causal schema intact, the
perceiver is apt to continue to see the event as
more likely to occur than would have appeared
likely prior to presentation of the now dis-
allowed information. As a result, any conditions
that induce an individual to explain an event
should lead the individual to regard that
event as more probable.
The present research was designed to test
directly the contention that the process of
explaining an event increases its subjective
likelihood for the perceiver. Three experiments
are reported, each dealing with explanations
and predictions of behavior in a clinical
judgment context. In Experiment 1, experi-
mental subjects attempted to explain events
that they believed to be authentic at the time
of their explanation task; however, before
making predictions, subjects learned that the
events were fictitious. To determine whether
the effects obtained in the first study were
dependent on subjects' initial beliefs in the
authenticity of the event, in Experiments 2
and 3 hypothetical explanation conditions were
added to the research design. Under these
conditions subjects knew the events to be
fictitious at the time of the explanation.
In all three experiments subjects were
provided with detailed case histories, and
experimental subjects were asked to write
down factors or reasons that might have led
the patient to a particular course of action.
It should be noted at the outset that these
explanation instructions represented compound
manipulations and that the present experi-
ments provided limited opportunity for iso-
lating the particular features of these manipu-
lations that are necessary or sufficient to
influence subjective likelihood. The subjects'
final task in each of these studies involved
estimating the likelihood of several possible
events in the patient's later life, including, of
course, the particular events experimental sub-
jects had previously explained.
Experiment 1
Method
Subjects
Forty-eight Stanford University undergraduates
served as subjects, receiving for their participation
either a $2 payment or credit toward a class require-
ment. Subjects participated in the study in small
groups, but they were randomly assigned to experi-
mental conditions on an individual basis, and they did
not communicate with each other during the session.
Experimental Materials
The experimental materials providing the basis for
the explanation and prediction tasks in this and the
succeeding experiments were two authentic clinical
case histories of approximately 3,000 words each taken
SOCIAL EXPLANATION AND SOCIAL EXPECTATION819
from a recent clinical casebook by Goldstein and
Palmer (1975). These two cabe histories, the cases of
''Shirie> K." and "George P ," involved descriptions of
the patient's presenting sj mptoms at the time she or he
sought professional help, together with an extensive
summary of possibly significant clinical information,
obtained through interviews with the patient, concern-
ing the patient's background and formative experiences
Both cases provided a wealth of detailed and potentially
diagnostic material on which subjects could draw in
explaining and predicting subsequent events in each
patient's life.
In one case, a \ oung housewife, Shirley K , arrived
at the clinic complaining of frequent headaches and
dizziness. She expressed great anxiety over her un-
controllable thoughts of harming her 2-year-old son
and repugnance for her current husband Her history
included an early and unhappy marriage to escape a
manipulating mother and restrictive father, a subse-
quent liason with a musician who fathered her son and
eventually committed suicide, and a current, abhorrent
marriage to a lawyer who was frequently unemploj ed
and unable to provide adequate support for his famih.
The report further described Shirley's reactions to the
suicide of her lover, the death of her father, and the
commitment of her mother to a mental institution.
In the other case, George P., a middle-aged bachelor,
was seen upon his readmission to a Veterans Admin-
istration hospital suffering from stomach pains and a
generalized weakness and malaise. His history included
an early separation from his family due to disagree-
ments with his father, a period spent as a hobo, a
subsequent term cf military service, involvement in a
number of unsuccessful business ventures, and his
eventual return home to care for his mother until her
death. The report also described George's previous
hospital admissions and health problems, his potential
difficulties with unadmitted alcoholism, and a recent
dispute which led George to resign from hib last job
as
a food machine serviceman.
Clearly, these two cases differed considerably in the
diagnostic material provided for subjects. The use of
two different cases, which were varied orthogonally
to the events to be explained, was simply an attempt to
insure that any results obtained would not be re-
stricted to a particular explanation/prediction context
Accordingly,
case
was treated as a factor in all of the
principal experimental analyses in the following studies.
With a single exception (to be reported in Experiment
2),
however, this factor exerted no influence relevant to
the experimental hypothesis; hence, the data were
collapsed across this dimension.
Procedure
Upon their arrival, subjects were seated and pre-
sented with a brief oral introduction to a study "in-
volving clinical judgments to be made on the basis of
actual case histories" The experimenter then dis-
tributed folders containing all relevant experimental
instructions, materials, and measures. The subjects'
written instructions first presented the purported
rationale for the study—an effort to contrast the
judgments of clinicians and laypersons in order to
isolate the effects of clinical training Subjects proceeded
to read about the "important clinical tasks" of explain-
ing past events and correctly anticipating future
developments while avoiding the pitfalls of either
overinterpreling or neglecting relevant case material
Finally, subjects were reminded that the\ would be
working with authentic case histories.
Control condition
—The 16 subjects in the control
condition proceeded to read one of the two clinical
case histories described above, with attention to
information about the patient's background, formative
experiences, and symptomatic problems that might
help predict later events in the patient's life Subjects
were then asked to rate the likelihood of occurrence of
each of five possible events in the patient's later life
These events were suicide, financial contributions to
the Peace Corps, participation in a dangerous medical
experiment, alcoholism, and volunteer work in a
political campaign.
Explanation
conditions.—The
32 subjects in the
explanation conditions also were asked to read one of
the two clinical case histories Hut in so doing, they
were asked to put themselves in the role of a clinical
psychologist who has just learned about a subsequent
event in the patient's life For half of the subjects the
relevant event was a successful suicide attempt
(suicide
condition),
for the remainder the relevant event was a
series of financial contributions to the Peace Corps
(Peace Corps condition)
The subjects were instructed,
furthermore, to
explain
the event in question as follows
•
"We are interested in what evidence, if any, you can
find in the case study that might help us to explain
or might have allowed us to anticipate Shirk)' K.'s
(or George P.'s) suicide (or contributions to the
Peace Corps) " Subjects were first required to write
down the "factors or reasons" that would explain a
particular course of action. Then the} were asked to
summarize the "main reason for the patient's action"
without further consulting the case history or their
notes.
Case history assignments and explanation
manipulations were orthogonal. Eight subjects were
assigned to each of the four possible pairings of cases
and events to be explained.
The instruction booklet then proceeded to inform
subjects in the explanation conditions that the experi-
menter did not, in fact, know anything about the life
of the relevant patient subsequent to the case history
period. In addition, subjects were specifically informed
that "no information is available about whether he
(she) committed suicide, made financial contributions
to the Peace Corps, or followed any other particular
course
of behavior." The booklet avoided any suggestion
that subjects had been deliberately misled; it simply
clarified the fact that no information was actually
available concerning the patient's later life. This
procedure was designed to discredit thoroughly the
authenticity of subjects' prior impressions and make
them realize that their explanations had merely been
hypothetical, without resorting to the debriefing
paradigm used in previous research. Finally, after
receiving this information, explanation subjects were
asked to rate the likelihood of occurrence of the same
820
ROSS,
LEPPER, STRACK, AND STEINMETZ
five pobsible events in the patient's later life that had
been rated by the control subjects, including the two
critical events that subjects in the two experimental
conditions had previously explained
Dependent measures
-The likelihood ratings provid-
ing the dependent measures in Experiment 1 were
introduced to all subjects as the "second important
task faced by clinicians, that of prediction." Subjects
were asked, specifically, to "compare the target person
with the average American male [female] of his [her]
age and to rate the likelihood that the patient would
manifest certain behaviors in the future " Each likeli-
hood estimate was made using a 9-point Likert-t) pe
scale from —4 (much less likely than the average
American male [female]) to +4 (much more likely
than the average American male [female]). A midpoint
labeled "about as likely as the average American male
[female]"'
was also provided.
Explanation-condition subjects first rated the likeli-
hood of the event they had explained, their third
rating (of the five ratings) dealt with the likelihood of
the event explained by the other explanation-condition
subjects. Half of the control subjects rated suicide
first and Peace Corps contributions third, the remainder
rated these events in reverse order1 The order of the
other events rated was constant across conditions
When subjects finished their assessments of subjective
likelihood for all five events, the experimental session
was concluded. The true purpose of the study and its
potential implications and possible personal relevance
were revealed to subjects in detail Subjects were
thanked for their participation and urged not to discuss
the study with their peers.
Results
Table 1 summarizes the effects of explana-
tion upon subjects' likelihood estimates for
suicide and Peace Corps contributions and
thus presents the data directly relevant to the
experimental hypothesis. An inspection of
Table 1 reveals that, as predicted, the task
of initially explaining a particular event in the
life of a patient increased subjects' subsequent
estimates of the actual likelihood of that
event's occurrence. A series of
2
(Event
Explained) X
2
(Case) analyses of variance
performed upon likelihood estimates for the
two critical events and upon the difference
between these estimates confirms the statistical
significance of the relevant effects.
First, a comparison of the two explanation
conditions reveals that suicide by the patient
was rated more likely by those subjects who
had initially explained suicide than by those
who had initially explained financial contri-
butions to the Peace Corps, P(\, 28) = 14.04,
p < .001. Conversely, Peace Corps contribu-
Table 1
Effects of Subject Explanation on Estimated
Likelihood of Events in Experiment 1
Estimated likeli-
hood of
Peace Difference
Corps in hkeli-
contri- hood
Event explained n Suicide butions estimates
Suicide 16 +2.33 -.84 +3.17
Peace Corps
contributions 16 +.17 +1.14 -.97
No explanation
(control) 16 +.50 -1.83 +2.33
Note Likelihood estimates are assessed relative to
the likelihood of the event occurring in the life of an
average American of the same age and sex as the
patient The more positive the number, the greater
the likelihood (up to a value of +4.00); the more
negative the number, the lesser the likelihood (up to
a value of -4.00).
tions were rated as more likely by the subjects
who had explained such contributions than b\
those who had explained suicide, F(l, 28) =
8.31,
p <
.01.
The effect of the event explained
on the difference between these two likelihood
estimates was, of course, highly significant,
^(1,
28) = 36.17, p < .001. Furthermore, con-
trol subjects who had explained neither event
rated both suicide and Peace Corps contribu-
tions as less likely than did those subjects who
had explained each of the two relevant events,
F(l, 28) = 6.98, p < .05, and
^(1,
28) =
22.61,
p < .001, respectively.
Significantly, subjects in the two explanation
conditions did not differ in their likelihood
estimates for any of the three events that had
never been the object of explanation in any
conditions (i.e., medical experiment partici-
pation, alcoholism, and volunteer political
work).
Nor were there any significant inter-
action effects between the events explained
and the case histories examined by subjects.
The effect of explanation, in other words, was
specific to the particular events that had been
1 It should be noted that the possibility of an order-
of-rating artifact influencing probability estimates is
dealt with explicitly, and discounted, through the
research design subsequently employed in Experiment i
SOCIAL EXPLANATION AND SOCIAL EXPECTATION821
explained but did not depend upon the content
of the particular case history used in the
explanation task. Having explained a patient's
purported later actions in terms of plausible
antecedent conditions described in a case
history, subjects rated that behavior (in the
absence of relevant data) as a relatively more
likely outcome.
Experiment 2
To extend and clarify these initial results,
the design of Experiment 2 added
hypothetical
explanation conditions to the nonhypothetical
conditions employed in the previous experi-
ment. Thus, half the subjects in Experiment 2
were again led to assume that an event had
actually occurred, were asked to explain the
event, and only then were made aware that
no information actually existed about the
occurrence or nonoccurrence of the event in
question. For these subjects, therefore, the
procedure was identical to that employed in
Experiment 1. For the remaining subjects, the
procedure was somewhat different. These
subjects were informed from the outset that
the event to be explained was merely hypo-
thetical—that is, they knew that no informa-
tion existed about the actual occurrence or
nonoccurrence of the critical event before
engaging in the hypothetical explanation task.
Investigation of the effects of such hypo-
thetical explanations was undertaken to assess
the relative plausibility of several alternative
accounts of the results of nonhypothetical
explanation conditions employed in the first
experiment. On a relatively trivial level, for
example, it seemed conceivable that some
subjects in Experiment 1 may have ignored
or failed to attend to the final experimental
disclaimer of knowledge concerning the
patient's later life and, accordingly, may
simply have persisted in their prior beliefs
about the patient. By making the hypothetical
nature of the explanation task explicit from
the outset, we sought to reduce the likelihood
of such responses.
At the same time, data from the hypothetical
explanation conditions introduced in Experi-
ment 2 promised to have relevance for more
substantive theoretical issues as
well.
Obviously
nonhypothetical explanation conditions con-
found the effects of explanation or construction
of plausible social schemata with the effects of
simply forming a firm initial belief in the
relevant event's occurrence. As a result, it
seems possible that the effects of explanation
upon subjects' subsequent beliefs concerning
the likelihood of an event in Experiment 1
ma}-
occur only as a function of the relative
irreversibility of subjects' initial beliefs (Ross
et al., 1975) or the seeming "certainty of
hindsight" enjoyed by subjects (Fischhoff,
1975,
1976, Fischhoff & Beyth, 1975). By
examining the effects of explicitly hypothetical
explanations and by comparing the relative
impact of hypothetical and nonhypothetical
explanations, we therefore hoped to explore
the extent to which our initial findings were
dependent upon such processes.
Method
Subjects
Thirty-two undergraduates of both sexes were
randomly assigned to experimental conditions m
Experiment 2 These subjects received credit toward a
course requirement for their participation
Design and Procedures
The two case studies, the two critical events to be
explained, and virtually all other instructions and
measures were identical to those employed m Experi-
ment 1. The only exceptions were the omission of the
control (no explanation) condition and the addition of
hypothetical explanation conditions.
In these added conditions subjects were informed at
the outset that the explanation task was merely
hypothetical, the following paragraph in the initial
task descriptions was presented to subjects
•
Now, of course, we don't actually know anything
about the behavior or experiences of George P.
[Shirley K.] after the writing of this case study, and
we have no way of finding out. We merely want you
to
imagine
that you, as a clinical psychologist, have
learned that George P. [Shirley K.] committed
suicide [contributed to the Peace Corps].
These subjects, like those in Experiment 1, also re-
ceived the explicit statement after the explanation
task that no information was available concerning the
patient's later life.
In the nonhypothetical explanation conditions, of
course, this additional paragraph was omitted, and the
subject searched the case history for antecedent causes,
believing that the event in question had actually
occurred. As in the experimental conditions of Experi-
ment 1, it was only after the explanation phase was
822
ROSS,
LEPPER, STRACK, AND STEINMETZ
Table 2
Effects of Hypothetical and Nonhypothetical
Subject Explanations on Estimated
Likelihood of Events
i?r
Experiment 2
Event explained
Suicide
Hypothetical
Nonhypothetical
Combined
Peace Corps
contributions
Hypothetical
Nonhypothetical
Combined
n
8
8
16
8
8
16
Estimated likeli-
hood of
Suicide
+2.94
+2.88
+2.91
+2 13
+ 100
+ 1.57
Peace
Corps
contri-
butions
-.25
-.31
- 28
+ .56
+ 1.09
+ .83
Difference
in likeli-
hood
estimates
+3 19
+3.19
+3.19
+
1
56
-.09
+.74
Note Likelihood estimates are assessed relative to
the likelihood of the event occurring in the life of an
average American of the same age and se\ as the
patient. The more positive the number, the greater
the likelihood (up to a value of +4.00); the more
negative the number, the lesser the likelihood (up to
a value of —4.00)
completed and the prediction phase was about to begin
that these subjects learned that no information actually
existed about the later life of the patient.
Results
The effects of hypothetical and nonhypo-
thetical explanations on subsequent likelihood
estimates for suicide and Peace Corps contri-
butions obtained in this second experiment are
summarized in Table 2. Overall, these results
clearly replicate and extend the phenomenon
demonstrated in Experiment 1.
Separate
2
(Event Explained) X 2(Hypo-
thetical/Nonhypothetical Explanation) X 2-
(Case) analyses of variance were performed on
the likelihood estimates for each of the two
events and on the difference between these two
estimates. For suicide ratings, the effect of
explanation was statistically significant,
F(l, 24) = 5.08, p < .05; that is, subjects
who explained suicide (hypothetical and non-
hypothetical conditions combined) rated suicide
as more likely than did subjects who had
explained Peace Corps contributions. For
Peace Corps ratings the relevant main effect,
although in the predicted direction, was not
individually significant, F(l, 24) = 2.41, p
> .10. The effect of event explained on the
difference between the two likelihood ratings,
however, was highly significant, F(l, 24)
= 10.82, p < .01. Moreover, in none of these
analyses did the interaction-between event
explained and the hypothetical /'nonhypotheti-
cal factor approach significance (all Fs <
1.25).
Finally, as in Experiment 1, explanation had
similar effects in the context of both case
histories but had no significant effect on likeli-
hood estimates for any of the three noncritical
events.
Comparing the relative impact of hypo-
thetical versus nonhypothetical explanations
on subsequent expectations, the data suggest
that both 13^63 of explanation had a sub-
stantial effect on subjective likelihood esti-
mates.
When
2
(Event Explained) X
2
(Case)
analyses of variance were performed, sepa-
rately for hypothetical and for nonhypothetical
explanation subjects, the sensitive dijference-
in-likeliltood-estimates
measure yielded a signifi-
cant effect of explanation for the nonhypo-
thetical explanation conditions alone, F(l, 12)
= 6.75, p < .05, and a marginally significant
effect for the hypothetical explanation condi-
tions alone, F(l, 12) = 4.21, p < .10, despite
the small sample sizes.
Nevertheless, the results provide some hints
that the relative impact of hypothetical and
nonhypothetical explanations may depend
upon the specific events explained and cases
involved. Among subjects who had explained
a patient's suicide, for example, the pattern
of results appears virtually identical for
hypothetical and nonhypothetical explanation
conditions. Among subjects who had explained
Peace Corps contributions, by contrast, the
effects of explanation seemed weaker for
hypothetical than for nonhypothetical condi-
tions,
although the relevant interaction effect
did not approach statistical significance.
Finally, on the difference-in-likelihood-esti-
mates measure, there was a significant second-
order (Event Explained X Hypothetical/Non-
hypothetical Explanation X Case) interaction,
F(l, 24) = 5.07, p < .05, suggesting that the
relative effects of the two types of explanation
may vary somewhat as a function of specific
contextual factors and circumstances. Further
SOCIAL EXPLANATION AND SOCIAL EXPECTATION823
experimental evidence relevant to the issue
of hypothetical versus nonhypothetical ex-
planation, however, and a further test of the
range of applicability of the more general
experimental hypothesis, are presented in the
third and final experiment.
Experiment 3
Experiment 3 again compared the effects
of hypothetical and nonhypothetical explana-
tion upon estimates of the subjective likelihood
that the explained event had indeed occurred.
To clarify and extend our earlier findings,
however, the design and procedures employed
in this study differed from those employed in
Experiment 2 in several important respects.
First, a new pair of critical events—involve-
ment in a hit-and-run accident and candidacy
for a seat on the city council—were substi-
tuted for the suicide and Peace Corps contri-
butions events that had been used in the two
previous experiments. This substitution was
largely an attempt to extend the generality
of the basic demonstration concerning the
effects of explanation. However, it also
permitted a further examination of the relative
impact of hypothetical versus nonhypothetical
explanation tasks with a second set of events
differing in their evaluative connotations and a
priori probabilities.
Second, to provide an appropriate baseline
for assessing the specific effects of the explana-
tion procedure on these two new events, a
no-explanation (control) condition was re-
instituted in Experiment 3. As in Experiment
1,
likelihood estimates from these control
subjects were obtained directly after exposure
to the case studies.
Finally, a third change in design was
dictated by the possibility that a simple
order
artifact
had played some role in the prior two
experiments. In these studies, subjects had
consistently first rated the likelihood of the
event they had previously explained and only
then rated the other four events. This con-
founding of order and explanation suggested
some obvious alternative interpretations of
results; hence, in Experiment 3, order of
prediction was made orthogonal to the desig-
nation of the particular critical event to be
explained.
Method
Subjects
A total of 80 undergraduates of both sexes served as
subjects in Experiment 3. Subjects were paid $2 for
their participation in the stud} and were randomly
assigned to conditions.
Procedure
With the exception of the changes noted above, the
procedures and measures in Experiment 3 differed from
those employed in the two previous studies only insofar
as was necessary in terms of the changes in critical
events. Thus, one new noncritical event (financial
contributions to Amnesty International) was substi-
tuted for one noncritical event (volunteer participation
in a political campaign) used in the previous studies.
Furthermore, minor editing of one case study was
undertaken, and dependent measures and details of
the instruction booklet were appropriately revised
Otherwise, the critical passages in the instruction
booklets dealing with the explicitly hypothetical or
implicitly authentic nature of the events to be explained
in the respective experimental conditions and the
procedure for obtaining subsequent subjective likelihood
estimates remained virtually unchanged from the
previous study
In this study, 64 subjects in the explanation condi-
tions explained one or the other of the two critical
events before making likelihood estimates, 16 subjects
in the control condition made these estimates without
any intervening explanation task Half of the subjects
first rated the likelihood of the patient subsequently
becoming involved in a hit-and-run accident, while
the other half first rated the likelihood of the patient's
subsequent candidacy for city council The alternative
critical event was always the third of the five events
rated by subjects, the second, fourth, and fifth events
rated, accordingly, were the noncritical events that no
subjects were induced to explain Within each explana-
tion condition, 4 subjects received each of the eight
possible combinations of hypothetical versus non-
hypothetical explanation, case, and order of events
to be predicted. Within the control condition, 4 subjects
received each of the four possible combinations of case
and order of events.
Results
Preliminary four-way analyses revealed no
significant main effects or interactions in-
volving the order-of-prediction variable. Subse-
quent analyses and presentations of data,
accordingly, were collapsed across this factor.
Table 3, then, presents the relevant mean
likelihood estimates. Inspection of these data
reveals that the primary experimental hypothe-
sis has been strongly confirmed. The likelihood
824
ROSS,
LEPPER, STRACK, AND STEINMETZ
Table 3
Effects of Hypothetical and Nonhypothehcal
Subject Explanations on Estimated
Likelihood of Events in Experiment 3
Event explained
Hit-and-run
accident
Hypothetical
Nonhypothetical
Combined
Running for city
council
Hypothetical
Nonhypothetical
Combined
No explanation
(control)
n
8
8
16
8
8
16
32
Estimated likeli-
hood of
Hit-
and-
run
accident
+ .59
+2 31
+
1
45
-.61
+.11
- 25
-.08
Running
for city
council
-2 73
-2.20
-2.46
+
1
41
-.09
+ 66
-1.55
Difference
in likeli-
hood
estimates
+3 33
+4 52
+3.92
-2.02
+ .20
- 91
+ 1.47
Note. Likelihood estimates are assessed relative to
the likelihood of the event occurring in the life of an
average American of the same age and bex as the
patient. The more positive the number, the greater
the likelihood (up to a value of +4.00); the more
negative the number, the lesser the likelihood (up to
a value of —4.00).
of the patient's subsequent involvement in a
hit-and-run accident was rated far greater by
subjects who previously explained such an
event (hypothetical and nonhypothetical con-
ditions combined) than by subjects who
explained the alternative event of city council
candidacy, F(l,56) = 9.86, p < .01. Con-
versely, the likelihood of city council candidacy
was rated greater by subjects who previously
explained that candidacy than by subjects
who explained the hit-and-run accident,
F(l,
56) = 39.36, p < .001. An analysis per-
formed on the difference between likelihood
estimates for the two events provides additional
dramatic evidence of the overall effects of
explanation on the estimated likelihood of
explained events, F(l, 56) = 36.75, p < .001.
Finally, as in Experiments
1
and 2, the relevant
effects were consistent across the two cases
presented to subjects, and none of the three
noncritical events showed any significant
effects of the subjects' explanation tasks.
The baseline provided by the no-explanation
(control) condition illustrates again the speci-
ficity of the explanation effects. In each
instance it is the rated likelihood of the
explained event rather than the alternative
event that is most removed from the baseline
estimate of control subjects. Thus, control
subjects regarded both the hit-and-run episode
and the city council candidacy as significant!}
less likely than did the relevant experimental
subjects who had previously explained each
of those events, F(\, 44) = 5.58, p < .05, and
F{\, 44) =
10.83,
p < .01, respectively.
Table 3 also summarizes the data comparing
the impact of hypothetical versus nonhypo-
thetical explanation. As in the previous experi-
ment, the effect of event explained on the
critical difference-in-likelihood-estimates mea-
sure was apparent both for the hypothetical
explanation conditions alone, ^(1, 24) = 24.3,
p < .001, and for the nonhypothetical condi-
tions alone, F(l, 24) = 18.0, p < .001. Once
again, however, it is difficult to assess the
relative magnitude of the effects of these two
different t>pes of explanation conditions. For
likelihood estimates concerning a hit-and-run
accident, nonhypothetical explanation condi-
tions seemed to have a slightly more powerful
impact than hypothetical explanation condi-
tions.
For estimates concerning city council
candidacy, this pattern was reversed ; that is,
subjects who explained the event knowing it
to be hypothetical showed a greater impact
of such explanation than subjects who ex-
plained the event believing it to have actualh
occurred. As in the previous experiment,
however, none of the interaction effects
involving the hypothetical versus nonhypo-
thetical explanation and event-explained fac-
tors approached conventional significance
levels.
Content and Quality of Subjects' Explanations
' In each of three studies, subjects in our
experimental conditions were asked to consider
available case study materials and to construct
from these materials a plausible explanation
for the possible occurrence of a subsequent
event in a patient's life. In each study, these
explanation procedures significantly increased
subjects' subsequent estimates of the likelihood
that the event in question had actuall)
SOCIAL EXPLANATION AND SOCIAL EXPECTATION825
occurred. Before proceeding to interpret and
discuss this effect, it seems appropriate to
describe briefly the nature of the actual
explanations provided by subjects in these
studies.
An examination of subjects' written explana-
tions reveals two general findings that, though
difficult to express in quantitative terms, may
be germane to the interpretation of the effects
that we have described. First, it seems clear
from subjects' explanations that both case
studies were sufficiently rich in detail and
complexity to allow virtually every subject to
construct at least one plausible framework or
script within which the critical event seemed
to make sense. Typically, these explanations
consisted of attempts to infer and document
consistent dispositional tendencies that seemed
to account for the patient's subsequent be-
havior (e.g., Shirley's inability to relate
intimately to other people, or her chronic
suppression of overt sexual impulses; or
George's inability to accept responsibility, or
his rebellious independence), coupled in many
cases with additional attempts to specify
particular early or critical experiences that
may have given rise to these propensities (e.g.,
the overprotectiveness of George's mother or
the suicide of Shirley's lover). In both Experi-
ment 2 and Experiment 3, moreover, there
were no detectable differences in the essays
written by subjects in the hypothetical and
nonhypothetical explanation conditions.2
Perhaps more striking than the general
plausibility of these essays, however, is the
extent to which subjects' explanations provided
qualitative evidence of the sorts of biases and
selective information-processing strategies that
we have suggested may underlie the effects
°f explanation on subsequent prediction. For
example, subjects clearly tended to interpret
the meaning or diagnostic significance of prior
events in the patients' lives quite differently
as a function of the event that they had been
asked to explain. Thus, George's naval service
was seen as evidence of his desire "to be with
People" by a subject who felt George's city
council candidacy was the result of his general
affiliative tendencies, but it was seen as
evidence of George's general "rebelliousness
against his parents" by a subject who felt his
suicide had been calculated to get back at
those who had made his youth unpleasant.
Similarly, the suicide of Shirley's lover was
seen by several subjects who had been asked
to explain her own suicide as a "model that
led her to take her own life," whereas other
subjects asked to explain her city council
candidacy or contributions to the Peace
Corps saw the same suicide as a significant
source of guilt which led Shirley to seek
expiation through public service or altruistic
concern for others. In these and numerous
other examples, the potential relevance and
possible predictive value of particular bits of
information about the patient appear to have
been colored by the explanation task subjects
had been given.
General Discussion
Taken together, the results of these three
experiments provide clear and consistent
support for the hypothesis that providing an
explanation for an event substantially in-
creases the subjective likelihood of the occur-
- A series of analyses were performed concerning the
length and persuasiveness (as rated by three "blind"
judges) of the subjects' written explanations in our
experimental conditions Xone of these analyses re-
vealed any significant or consistent differences between
h>pothetical and nonhypothetical conditions (all
b\ < 1.0). Additional!}', correlations between subjects'
likelihood estimates and the length and persuasiveness
of these explanations were calculated (collapsing across
the hypothetical/nonh\ pothetical variable). These
analyses provided no evidence that either length or
persuasiveness was consistently associated with
heightened subjective likelihood. The relevant corre-
lations involving length and estimated likelihood were
generally positive, although they never reached
accepted significance levels The correlations involving
persuasiveness and estimated likelihood were in-
consistent, ranging from moderately positive to moder-
ately negative values. In fact, the only statistically
significant correlation obtained indicated that those
subjects in Experiment 3 who wrote the most persuasive
explanations for a patient's city council candidacy
were the least inclined to estimate such a candidacy as
likely (r = .54, p < .01). Obviously, one should
interpret a single unpredicted but significant correlation
in the midst of a number of nonsignificant ones with
considerable caution, recognizing that multiple interpre-
tations (not excluding chance) could be offered. We
can at least conclude, however, that no simple positive
relationship existed between the length or quality of
the subjects' written explanations for an event a,nd their
beliefs concerning the likelihood of that event.
826
ROSS,
LEPPER, STRACK, AND STEINMETZ
rence of the event. Having generated a
plausible account for suggesting how a particu-
lar event might have been predicted from
know ledge of a patient's prior history, subjects
appeared consistently willing to make the
inferential leap from possibility to probability.
Furthermore, the effect of explanation upon
estimated likelihood occurred, even when
subjects were not initially led to believe that
the events had actually occurred. Though the
data provided some intriguing hints that the
relative impact of hypothetical and non-
hypothetical explanation procedures may de-
pend upon specific characteristics of the case or
event to be explained, it is clear that the task
of explanation enhanced subjective likelihood,
even when subjects recognized from the outset
that the event described (and, hence, the task
of explanation) was purely hypothetical.
The theoretical significance of the results
obtained in the hypothetical explanation
condition should be quite clear. These data
help to eliminate a number of possible alter-
native interpretations that otherwise might be
offered to account for the effects obtained in
nonhypothetical explanation conditions alone.
First, the hypothetical condition procedures
largely rule out explanations involving the
simple failure of subjects to attend or take
seriously the experimenter's eleventh-hour
disclaimers concerning the availability of
knowledge about the patient's later life. In
the hypothetical conditions, unlike the non-
hypothetical conditions, subjects were clearly
informed from the outset that their explana-
tions and predictions would deal with purely
hypothetical events. Perhaps more signifi-
cantly, the results of the hypothetical condition
suggest that the relevant distortions in subjec-
tive likelihood seem to have been neither simple
instances of impression perseverance in the
face of subsequent discrediting information
(Ross et al., 1975) nor the product of specific
biases introduced when events are viewed
with "the certainty of hindsight" (Fischhoff,
1975,
1976, 1977; Fischhoff & Beyth, 1975;
Slovic &
Fischhoff,
1977).
Indeed, the results obtained in the present
hypothetical explanation condition suggest a
fruitful perspective for viewing the research
findings relevant to both hindsight and
perseverance phenomena. Attribution theo-
rists have long contended (cf. Heider, 1944,
Kelley, 1967) that the occurrenceofasignificant
and/or unanticipated event is likely to evoke
a search for some explanatory framework that
will allow the individual to make sense of the
event. The present research, moreover, suggests
that the search for possible links between
specified consequences and possible ante-
cedents may itself be sufficient for producing
changes in likelihood estimates of the type
observed in previous research. Thus, the
apparent inevitability that events seem to
accrue when viewed with hindsight may
result, in large part, from the explanatory
framework the individual has generated in
reflecting upon that event. Similarly, the
formation of perceived antecedent-conse-
quence linkages postulated by Ross et al.
(1975) to underlie post-discrediting impression
perseverance need not be the product of
initial certainty about the relevant conse-
quences; any circumstances, in fact, that lead
the subject to generate such explanations may
foster subsequent impression perseverance.
Implications, Alternative Interpretations, and
Boundary Conditions
It is perhaps difficult to identify circum-
stances in everyday experience that are
exactly paralleled by the present experimental
conditions—particularly those involving hypo-
thetical explanation. In a very general sense,
however, there are many circumstances in
which social decision makers—and those
experts who advise them—are forced both to
make predictions and to explain or identif}
the antecedent factors that justify such
predictions. Clinical, educational, and correc-
tional settings and many social and political
planning tasks characteristically demand com-
plexly related inferences about the necessit}
and sufficiency for the link between existing
antecedents and one or more possible future
outcomes. Guidance counselors, parole board
members, and military contingency analysts,
for instance, frequently are required to consider
and assess the likelihood of various alternative
outcomes that are merely hypothetical at the
time of analysis and prediction. Are judgments
and actions in such circumstances distorted
by biasing effects of explanation upon per-
SOCIAL EXPLANATION AND SOCIAL EXPECTATION827
ceived likelihood? Does the act of justifying
a prediction or explaining its basis (i.e., by
identifying the antecedents that might lead
to the predicted outcome or event) produce
unwarranted subjective certainty about one's
decisions? The present research raises, but
obviously cannot answer, these important
questions.
In view of the complexities of these applied
questions, it should also be recognized that
the instruction to explain an event is itself a
compound manipulation with several com-
ponents and consequences. In the present
experiments, subjects were provided with a
great deal of raw material from which to
construct an explanation; they were led to
anticipate the subsequent explanation task as
they read the relevant material; they were
asked to write down antecedents; and they
were asked to underscore the particular causes
or explanations they deemed most critical.
Obviously, at present we cannot specify which
of these components were necessary and/or
sufficient to increase subjective likelihood
estimates. For instance, subjects' responses
as they read the case history may well have
been influenced by the anticipation of the
explanation task they were to undertake.
Was such anticipation necessary, or could an
after-the-fact explanation manipulation have
similarly enhanced subjective likelihood? Alter-
natively, was such anticipation sufficient, or
was the subsequent production and under-
scoring of explanations required to produce
such results? These questions furnish an
obvious topic for future research.
Perhaps a more serious challenge to the
interpretation and implications of the present
demonstrations involves the role of salience.
Specifically, it is possible that the task of
explaining a particular clinical outcome was
likely to leave that outcome more salient than
nonexplained outcomes, even after its authen-
ticity was subsequently undermined. This
heightened salience rather than the explana-
tion task itself could have, in turn, distorted
subjects' ultimate likelihood estimates. We
cannot dismiss this alternative interpretation
on the basis of the present evidence, although
it is worth emphasizing that the explanation
manipulation did seem to influence the
subjects' interpretation of the case history
materials as well as their final likelihood
estimates.
One may be tempted to resolve the salience
issue by simply manipulating outcome salience
in the absence of an explicit explanation task.
The difficulty with such a strategy, however,
is obvious. A salience manipulation alone may
lead subjects to read and review case history
material in terms of its capacity to explain
this salient outcome, even in the absence of
any explicit experimental instruction to do so.
Indeed, a manipulation of outcome salience
is but one of many types of cognitive manipu-
lations and factors relevant to social per-
ception that may influence the likelihood of
causal explanation or the nature of the explana-
tions that are formed. The personal relevance
of events in question, the extent to which
such events seem to violate prior expectancies
or theories, and a host of instructional or
contextual variables that affect one's point
of view (cf. Abelson, 1976) all seem likely to
play a role in determining when and how
individuals will undertake the cognitive work
involved in causal attribution (Abelson, 1972;
Bern, 1970).
Certainly, painstaking research will be
required to explicate the types of cognitive
events that influence subjective likelihood and
the precise role of causal explanation in such
influence. For the present, however, our own
suspicion is that the production of formal
causal propositions may not be a necessary
condition for, or even a frequent characteristic
of, the process by which explanation affects
subsequent expectations. That is, it seems
probable that the mechanisms responsible for
the present results, and more importantly the
mechanisms operating in most familiar social
prediction contexts, may be far less systematic
and logical than those suggested by current
models of the attribution process (e.g., Kelley,
1967,
1972). Rather, the individual's effort
at interpretation may be more accurately
characterized as an attempt to construct or
imagine a scenario or causal script (Abelson,
1976) into which the event can be easily fit.
In this attempt, material that is concrete,
salient, or of high associative value may be
used extensively, whereas logically significant
but more abstract evidence may be largely
neglected (cf. Nisbett & Borgida, 1975).
828
ROSS,
LEPPER, STRACK, AND STEINMETZ
Correspondingly, individuals may be likely to
evaluate the appropriateness and explanatory
power of a possible script by "satisficing"
rather than "optimizing" criteria (Simon,
1957).
Hence conditions that promote the
availability (Tversky & Kahneman, 1973) of
even a single coherent and plausible script
in which an event appears as a probable final
episode may prove sufficient to heighten the
perceived likelihood of that event's occur-
rence, even if the relevant script is not the
most satisfying or plausible one that could be
generated by the individual.
Implicit in our discussion of the link between
satisfactory explanations and heightened sub-
jective likelihood, of course, is the requirement
that subjects be both able and willing to
construct plausible causal scenarios or scripts.
In the present studies, as we have noted, the
case study materials provided a rich source of
information for the explanation task, and
subjects had little difficulty in selectively
sampling and interpreting details to achieve
this end. However, one can readily imagine
situations in which attempts at explanation or
script construction will be apt to fail. Although
the present studies provide no relevant
evidence, it seems quite possible that such
failures may lead to decreases, not increases,
in subjective likelihood.
If our speculation that informal scenarios
and scripts influence social expectation is
proven to be correct, however, the practical
implications of tlie present research, as well
as the theoretical
ones,
will be greatly increased.
Indeed, any social decision in which one must
use information about the past to guide and
justify future courses of action would be
potentially subject to such influences.
Conclusions
The present experiments demonstrate that
the act of providing a causal explanation of
an event will increase the subjective likelihood
of that event's actual occurrence. This increase
in subjective likelihood as a function of explana-
tion was demonstrated across a variety of
specific events and was shown to occur whether
the explanation task involved an attempt to
explain an event that the subject initially
believed actually had occurred or an attempt
to provide an explanation for an event pre-
sented as purely hypothetical from the outset.
These findings clarify previous investigations
dealing with belief perseverance and with the
consequences of hindsight. They also prompt
more general discussion of the cognitive
components and consequences of explanation
manipulations, the relationship between ex-
planation and prediction, and the boundary
conditions that may govern this relationship.
Reference Notes
1.
Lau, R. R., Lepper, M. R., & Ross, L. Persistence
of
inaccurate and discredited personal impressions: A
field demonstration of altributional perseverance.
Paper presented at the 56th Annual Meeting of the
Western Psychological Association, Los Angeles,
April 1976.
2.
Jennings, D., Lepper, M. R., Ross, L., & Steinmetz,
J. Persistence in impressions of personal persuasive-
ness: The perseverant impact of discredited success
and
failure experiences. Unpublished manuscript, Stan-
ford University, 1977.
References
Abelson, R. P. Are attitudes necessary? In B. T. King
& E McGuinnies (Eds.), Attitudes, conflict, and
social change. New York. Academic Press, 1972.
Abelson, R. P. Script processing in attitude formation
and decision making. In J. S. Carroll & J. W. Payne
(Eds.),
Cognition and social beliavior. Hillsdale, N.J..
Erlbaum, 1976.
Bern, D. J. Beliefs, altitudes and human affairs Belmont,
Calif.:
Brooks-Cole, 1970.
deCharms, R. Personal causation. New York: Academic
Press,
1968.
Fischhoff,
B. Hindsight ^ foresight: The effect of
outcome knowledge on judgment under uncertainty.
Journal of Experimental Psychology: Human Per-
ception and Performance, 1975,1, 288-299.
Fischhoff,
B. Attribution theory and judgment under
uncertainty. In J. H. Harvey, W. J. Ickes, & R F.
Kidd (Eds.), New directions in attribution
research
Hillsdale, NJ.: Erlbaum, 1976.
Fischhoff,
B. Perceived informativeness of facts
Journal of Experimental Psychology: Human Per-
ception and Performance, 1977, 3, 349-358.
Fischhoff,
B., & Beyth, R. "I knew it would happen"—
Remembered probabilities of once-future things
Organizational Behavior and Human Performance,
1975,
13, 1-16.
Goldstein, M. J., & Palmer, J. O. The experience o)
anxiety. New York: Oxford University Press, 1975.
Heider, F. Social perception and phenomenal causality-
Psyclwlogkal Review, 1944, 51, 358-374.
Heider, F. The psychology of interpersonal relations-
New York: Wiley, 1958.
Jones,
E. E., & Davis, K. E. From the acts to disposi-
SOCIAL EXPLANATION AND SOCIAL EXPECTATION829
tions.
The attribution process in person perception.
In L. Berkowitz (Ed.), Advances in experimental
social psychology (Vol. 2). New York- Academic
Press,
1965.
Jones,
E. E., et al. (Eds.). Attribution- Perceiving the
causes of behavior. Morristown, N.J.: General
Learning Press, 1972.
Kelley, H. H. Attribution theory in social psychology.
In D Levine (Ed.), Nebraska Symposium on Motiva-
tion (Vol. 15). Lincoln: University of Nebraska
Press,
1967.
Kelley, H. H. Attribution in social interaction In E. E.
Jones et al. (Eds.), Attribution: Perceiving lite
causes of beltavior. Morristown, N.J.
•
General
Learning Press, 1972.
Kelley, H. H. The processes of causal attribution
American Psychologist, 1973, 28,107-128.
Kruglanski, A. W. The endogenous-exogenous partition
in attribution theory. Psychological Review, 1975,
82,
387-406.
.Visbett, R. E., & Borgida, E. Attribution and the
psychology of prediction. Journal of Personality and
Social Psyclwlogy, 1975, 32, 932-943.
Ross,
L. The intuitive psychologist and his short-
comings: Distortions in the attribution process. In
L. Berkowitz (Ed.), Advances in experimental social
psychology (Vol. 10). New York: Academic Press,
1977.
Ross,
L., Lepper, M R , & Hubbard, M. Perseverance
in self-perception and social perception: Biased at-
tributional processes in the debriefing paradigm.
Journal of Personality ar.d Social Psychology, 1975,
32,
880-892.
Simon, H. S. Models of man. New York: Wiley, 1957.
Slovic, P., &
Fischhoff,
B. On the psychology of
experimental surprises. Journal of Experimental
Psychology: Buman Perception and Performance,
1977,
3,
544r-551.
Tversky, A., & Kahneman, D. Availability: A heuristic
for judging frequency and probability. Cognitive
Psychology, 1973, 5, 207-232.
Received March 14, 1977 •
Announcement for Student Subscribers Outside the United States
Students in psychology programs outside the United States are eligible to subscribe
to the Journal of Personality and Social Psychology at the rate of $20 for 1978.
This is the same rate paid by members of the American Psychological Association.
In order to obtain a Student in Psychology application and order form to subscribe
to JPSP and all other APA journals, write to Box M, American Psychological
Association, 1200 Seventeenth Street, N.W., Washington, D.C. 20036, U.S.A.
