Psychonomic Bulletin & Review
2001, 8 (2), 331-335
A fundamental question in cognitive science is how
humans selectively attend to certain aspects of their environment,enablingdetailed
processing of those aspects,
while of necessity ignoring other aspects. Beginning in
England during World War II, psychologists developed
laboratory tasks to identify individualsskilled in attending
within a busy environment (Lachman, Lachman, &
Butterfield, 1979). Cherry (1953) developedthe dichotic
listeningprocedure in which the task is to repeat aloud or
“shadow” the message presented to one ear and ignore a
different message presented to the other ear. Subjects
were very successful in this task, but when asked to recall
the content of an ignored message, they were able to
report only physical features such as gender of the voice
or whether the message was speech or tone; little or no
semantic content was reported. Partly on the basis of this
work, Broadbent (1958) developed a theoretical model
of selective attention, according to which environmental
stimulation is filtered out of awareness if it is identified
as irrelevant to the subject’s current concerns on the basis
of its superficial physical features (e.g., voice, color, or
location).
Broadbent’s (1958) model has been seriously challenged,however,
by demonstrations of semantic processing
of unattendedinformation.For example,Moray (1959)
found that some subjects detect their own name when it
is presentedin an unattendedauditorychannel.Contrary to
popular belief, not all subjects demonstrate this “cocktail
party effect.” In fact, Moray found that only 33% of subjects
reported hearing their own name when it is inserted
into the irrelevant message. Using more sophisticated
technology, Wood and Cowan (1995) replicated Moray’s
experiment and found 34.6% of subjectsreported hearing
their own name presented in the irrelevant message.
The purpose of the present experimentis to explain why
some, but not all, subjects demonstrate the cocktail party
effect. An examination of individual differences in the
cocktail party effect raises some interestingpossibilities.
On the one hand, it is possible that the most capable subjects
notice their names because they are able to monitor
the irrelevant message with no damage to shadowing performance.
On the other hand, it is possible that only the
least capable subjects notice their names because they
are poor at maintaining attention on the relevant message
in the presence of distraction.
We measured subjects’ capability using the construct
of working memory, which is considered to be a cognitive
system consisting of storage buffers as well as a central
executive control mechanism. The function of working
memory is to actively maintain goal-relevantinformation
in the service of complex cognition (Baddeley & Hitch,
1974; Miyake & Shah, 1999). The limited capacity of
working memory presumably constrainscognitiveperformance.
We measured this capacity with the operation
span task (Turner & Engle, 1989), in which series of displays
were presented, each containing a simple mathematical
problem and an unrelated word. The span was
based on the length of the series that could be processed
331 Copyright 2001 Psychonomic Society, Inc.
This work was supported by NIH Grant R01 HD-21338. Please
address correspondence to A. R. A. Conway, University of Illinois, Department
of Psychology(M/C 285),1007 West Harrison Street, Chicago,
IL 60607-7137(e-mail: aconway@uic.edu).
The cocktail party phenomenon revisited:
The importance of working memory capacity
ANDREW R. A. CONWAY
University of Illinois, Chicago, Illinois
NELSON COWAN
University of Missouri, Columbia, Missouri
and
MICHAEL F. BUNTING
University of Illinois, Chicago, Illinois
Wood and Cowan (1995) replicated and extended Moray’s (1959) investigation of the cocktail party
phenomenon, which refers to a situation in which one can attend to only part of a noisy environment,
yet highly pertinent stimuli such as one’s own name can suddenly capture attention. Both of these previous
investigations have shown that approximately 33% of subjects report hearing their own name in
an unattended, irrelevantmessage.Here we show that subjects who detect their name in the irrelevant
message have relativelylow working-memory capacities,suggesting that they have difficulty blocking
out, or inhibiting, distracting information.
332 CONWAY, COWAN, AND BUNTING
with the subjectstill able to recall all of the words. Various
investigations have demonstrated that individuals with
high working-memory capacity out-perform individuals
with low working-memory capacity on a range of tasks
(Daneman & Carpenter,1980;Daneman & Merikle,1996;
Engle, Tuholski, Laughlin, & Conway, 1999; Gilhooly,
Logie, Wetherick, & Wynn, 1993; Toms, Morris, &
Ward, 1993) and that individualswho score high on tests
of working-memory capacity are better at blocking out,
or inhibiting, distracting information (Conway & Engle,
1994; Conway, Tuholski, Shisler, & Engle, 1999; Gernsbacher,
1993; Hasher & Zacks, 1988; Rosen & Engle,
1997). We used the operation span task to identify high
and low working-memory capacity individuals and had
subjects perform a dichotic listening task in which their
own name was presented in the irrelevant message, following
as closely as possible the procedure reported by
Wood and Cowan (1995).
METHOD
Subject Selection
The sample comprised 40 (17 male, 23 female) native English
speaking undergraduates from the University of Illinois at Chicago
with normal hearing, who received course credit for participation.
Informed consent, approved by the local internal review board, was
obtained from all subjects. Half were categorized as having a high
working-memory span and half a low working-memory span on the
basis of scores that fell in the upper or lower quartile of a larger
sample of subjects who carried out the operation span task. All subjects
repeated the same relevant message, but half of each span
group was randomly assigned to an experimental condition in which
the subject’s first name occurred after 4 min of shadowing and the
other half, after 5 min of shadowing. Any subject who received his
or her name at 4 (or 5) min also received a yoked subject’s name at
5 (or 4) min.
Operation Span Task Procedure
The procedure was adapted from a previous study (Turner &
Engle, 1989) to measure working memory capacity. The subject
was presented with a series of displays on a computer screen. Each
display contained a mathematical operation and an unrelated word
(e.g., IS (6+4)/2 5 5 ? DOG). The subject’s task for each display
was to say the equation aloud, answer “yes” or “no” as to whether
the equation was true, and then say each word. When the series of
displays ended, the task was to write all of the words on a response
sheet. The number of displays in a series varied from 2 to 6. Three
series of each length were presented for a total of 15 series, with series
length randomized and not predictable by the subject. The subject’s
span score was the cumulative number of words recalled from
series that was perfectly recalled in the correct serial order, with no
points awarded for imperfect recall of a series. The average score
was 24.85 (range of 17– 44) for high-span subjects and 8.22 (range
of 6–12) for low-span subjects. Subjects in the middle two quartiles
of the range of span scores were omitted from the study. Performance
levels on various versions of verbal working-memory tasks
like this one are highly correlated with one another (Daneman &
Merikle, 1996; Engle et al., 1999).
Selective Listening Procedure
Subjects were tested individually in a well illuminated, soundinsulated
room. The auditory stimuli, obtained from Wood and
Cowan (1995), were recorded onto a normal-bias audio cassette and
then digitized onto a computer at a sampling rate of 22 kHz and dynamic
range of 16 bits. They were presented through stereo headphones
at a constant volume for all subjects. The relevant message
contained 330 monosyllabic words recorded in a monotone female
voice at the rate of 60 words per minute and lasted 5.5 min. The irrelevant
message contained 300 monosyllabic words recorded in a
monotone male voice. The onset of the irrelevant message began
30 sec after the attended message, allowing for a brief practice period
without distraction. The onsets of the words were synchronized
across messages. The order of the words was identical across subjects
except for the names, which were digitally inserted into the irrelevant
message in place of a word after 4 and 5 min of shadowing.
Each subject’s first name was inserted into the irrelevant
message. The experimenter was aware of each subject’s name because
each had previously been in the lab to perform the operation
span task.
Subjects were instructed to listen to the message presented to the
right ear and to repeat (shadow) each word as soon as it was presented,
making as few errors as possible and to ignore the distractions
coming to the left ear. Subjects shadowed until all sounds in
the attended message stopped. During shadowing, the experimenter
was seated at a separate table in the same room and recorded shadowing
errors. After shadowing, the subject completed a questionnaire
regarding the irrelevant message, identical to one used by
Wood and Cowan (1995). Subjects stating that they detected something
unusual in the irrelevant message when queried all went on to
specify that it was their own name.
RESULTS AND DISCUSSION
Using retrospective report immediately after the shadowing
task, we found that 20% of high-span subjects and
65% of low-span subjects reported hearing their name in
the irrelevant message (see Figure 1). Fisher’s exact test
indicated that the probability of obtaining these proportions
by chance alone (under the assumption that highand
low-span subjects actually are equally prone to detecting
their name in the irrelevant message) is only p 5
.005. No subject reported hearing a yoked control subject’s
name that also was presented. Clearly, the low-span
subjects detected their own names more often.
Figure 1. The proportion of high- and low-span subjects who
reported hearing their name in the irrelevant message.
COCKTAIL PARTY PHENOMENON AND WORKING MEMORY 333
Low-span subjects also encountered more difficulty
performing the shadowing task. This is reflected in the
finding that low-span subjects committed significantly
more shadowing errors (M 5 20.88) than did high-span
subjects (M 5 10.00) [t(32) 5 2.18, p 5 .04]. Given this
finding, we wanted to ensure that the name-detection
difference between high- and low-span subjects was not
simply a result of more attention shifts on the part of the
low-span subjects.Therefore, we examinedshadowing errors
for the two words in the relevant message preceding
Figure 2. The number of high- and low-span subjects who did and did not notice their own names in the irrelevant
message in a selective listening task (heights of frequency bars), and the proportion of those subjects
who made errors in shadowing words in the relevant message (dark portion of bars) that occurred 1, 2, or 3
words after the subject’s name (abscissa parameter). Panel A: High-span subjects who noticed their names.
Panel B: High-span subjects who did not notice their names. Panel C: Low-span subjects who noticed their
names. Panel D: Low-span subjects who did not notice their names. Many more low-span subjects noticed
their names, and subjects who noticed their names made proportionally many more shadowing errors in the
name+1 and name+2 positions.
334 CONWAY, COWAN, AND BUNTING
the name. There were no group differences in shadowing
two words before the name [t(32) 5 1.0, p >.10] or one
word before the name [t(32) 5 1.0, p > .10], rulingout the
possibilitythat the low span subjectsdetected their names
more often than did the high-span subjects, simply because
their attention wandered to the irrelevant message
at the opportunetime (in fact, only one person committed
a shadowing error on either word). There was a difference
between high- and low-span subjects in shadowing errors
committed concurrently with the presentationof the
name [t(32) 5 2.59,p 5 .01], suggestingthat the presentation
of the name resulted in distraction much more so
for low-span subjects.
We also examined shadowing errors after the presentation
of the name. Presumably, detectingone’s own name
in the irrelevant message would result in a decrement to
performance of the shadowing task. As shown in Figure
2, a much higher proportion of subjects who noticed
their name made shadowing errors on the two words following
the name (marked “name+1” and “name+2”). On
the two words to be shadowed immediately after presentation
of their own name, high-span subjects who reported
hearing their name made significantly more shadowing
errors than those who did not [t(15) 5 3.04, p 5
.01]. Similarly, on these two words, low-span subjects
who reported hearing their name made more shadowing
errors than those who did not [t(15) 5 2.50, p 5 .03].
Thus, the pertinenceof the subject’s own name sometimes
served as a distraction and resulted in a reallocation of
attention to the name, significantly more frequently in
low-span subjects. However, this distraction did not persist
for more than two words. High-span subjects who reported
hearing their own name were no more likely to
commit a showing error three words after the name than
were high-span subjects who did not report hearing their
own name [t(15) 5 0.75, p > .10]. Similarly, low-span
subjects who reported hearing their own name were no
more likely to commit a shadowing error three words after
the name than were low-span subjectswho did not report
hearing their own name [t(15) 5 1.74, p > .10].
The higher incidence of name detection in low-span
subjects is particularly striking because the opposite result
was possible. It could have been that high-span subjects,
because of their greater capacity, have the ability to
monitor the irrelevant message so as to hear their names.
This certainly was not the case. The critical factor seems
to be the ability to block information from the irrelevant
message. High-span subjects are more capable of this
and were therefore less likely to hear theirnames, and they
also were less susceptible to a consequential disruption
of relevant task performance.
Also striking is that the operation span task is essentially
a divided attention task, whereas the dichotic listening
task is clearly a selective attention task, yet subjects
who performed well on one task also performed
well on the other. Therefore, it is clearly not the case that
some subjects habitually or spontaneously divide their
attention when performing cognitivetasks. Rather, it appears
that there is a general cognitive ability that allows
subjects to perform well on both tasks. We argue that this
ability is intimately linked to working memory capacity.
Working memory capacity is a critical cognitive characteristic,
and one’s capacity has a major impact on the
quality of cognitiveperformance. Some researchers even
suggest that working memory capacity is the most important
factor in general fluid intelligence (Conway,
Cowan, Bunting, Therriault, & Minkoff, in press; Engle
et al., 1999; Kyllonen, 1996). A fundamental aspect of
intelligent behavior, linked to working memory, is the
ability to inhibit distracting information (Dempster,
1991). Although the present experiment does not provide
direct evidence of inhibitionof information presented in
the irrelevant channel, the interpretation that high-span
subjects are better at inhibiting distracting information
than are low-span subjects is consistent with previous research.
For example, in the context of memory retrieval,
several experiments have demonstrated that high-span
subjects are more likely to reveal retrieval inhibition effects
and subsequentlyless proactive interference than are
low-span subjects (Conway & Engle, 1994; Kane &
Engle, 2000; Rosen & Engle, 1997, 1998). Also, highspan
subjects reliably reveal the negative priming effect,
whereas low-span subjects do not (Conway et al., 1999).
Whether or not an inhibitory mechanism is necessary to
account for these findings, it is clear that the ability to
handle cognitive interference is a dimension on which
high- and low-working memory span individuals differ.
Finally, the present result does not answer the question
of whether working memory capacity drives inhibitory
ability or vice versa. One interpretation is that working
memory capacity is a “resource” that fuels the central
executive, which is responsible for maintaining activation
to relevant information and suppressing distracting
information (Conway & Engle, 1994). Another interpretation
is that working memory capacityrefers to the “contents”
of working memory, and as such, inhibitory ability
regulates the contents and therefore the capacity of
working memory (Hasher & Zacks, 1988). The present
results are compatible with either view. Our goal here is
not to resolve this issue but to demonstrate the importance
of working memory for classic selective attention tasks
such as dichotic listening and to possibly extend the
range of tasks of working memory that will be investigated,
which will ultimately lead to a better understanding
of the working memory system, selective attention,
and inhibition.
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(Manuscript received July 22, 1999;
revision accepted for publication June 14, 2000.)