What is attention?
3
Everyone knows what attention is. It is the taking
possession of the mind, in clear and vivid form,
of one out of what seem several simultaneously
possible objects or trains of thought.
Focalisation, concentration, and consciousness
are its essence.
William James
(1890)
Endogenous vs Exogenous
4
Active: When attention is controlled in a top-down
fashion -- endogenous orienting.
Passive: When attention is controlled in a bottom-up
manner by external stimuli -- exogenous orienting.
Focused vs. Divided
5
Focused attention: Paying attention to one thing at a
time. It is studied by presenting people with 2 or more
stimulus inputs simultaneously and instructing them to
respond to only one.
Divided attention: Multiple stimuli are presented and
subjects must attend to and respond to all stimuli.
Neglect Syndrome
7
9
Focused Auditory Attention
10
The cocktail party problem (Cherry)
He wanted to know what happens to the verbal stimuli that is
being ignored. Do people automatically process information
that they ignore?
In a dichotic listening task, he asked subjects to shadow one
channel. Later he asked subjects what was presented in the
unattended channel. Listeners seldom noticed when that
message was spoken in a foreign language or even in reverse
speech.
People often have no memory of information presented in the
unattended channel -- even if the information was presented
35 times (Moray, 1959)!
How to Account for These Findings?
12
Two stimuli presented simultaneously gain access to
the sensory buffer in parallel. But a filter allows one
input to pass through for more thorough processing
based on physical characteristics.
The blocked stimuli is put on hold.
The filter prevents overloading of the limited
capacity attention system.
Donald
Broadbent
13
Broadbent’s Theory of Selective Attention
Broadbent’s Model
14
Broadbent presented subjects with a different set of 3
digits to each ear and then asked them to recall the digits.
E.g., he presented 4-6-2 to one ear and 3-5-1 to the other
ear.
Subjects almost always recalled the digits by ear rather
than by pair. That is, they almost never recall the digits by
pair such as 4-3, 6-5, 2-1, even though these numbers
occur simultaneously.
Physical characteristics is defined by ear here.
Attentional Filtering Based on
Physical Characteristics
15
Two audio streams will be played simultaneously.
Try to hear all the digits spoken!
Same Pitch
Different Pitch
An Early Selection Model
17
The theory assumes that stimulus selection happens
early in the processing stream -- it occurs once the
stimuli go into sensory stores.
Due to the effectiveness of this stimulus selection filter,
very little to no information presented via the
unattended channel is processed.
But is this true?
Turns out the filter does not block out everything from
the unattended channel for further processing.
Gray & Wedderburn (1960)
Dichotic Listening and Shadowing
Left ear: Dear, 7 , Jane
Right ear: 9, Aunt, 6
Subjects reported hearing Dear, Aunt, Jane
18
19
Expertise
In a dichotic listening-shadowing task, Underwood
asked either naive subjects or an experienced
researcher to detect a target digit.
Inexperienced subjects detected only 8% of the digits
in the nonshadowed message. The researcher
detected 67% of them.
Clearly, the filter may not work as well as Broadbent
had assumed.
Benton
Underwood
But what happens to undetected messages?
Does Unattended, or Undetected,
Information Get Processed?
20
Von Wright, Anderson, and Stenman (1975) asked
subjects to perform a dichotic listening-shadowing
task.
Some words presented in the nonshadowed channel
are associated with an electric shock...
Does Undetected Information
Get Processed?
21
Subjects report no awareness of these words.
But they show heightened galvanic skin response (GSR)
to these words.
A heightened GSR is usually associated with a
heightened emotional state such as anger, fear, surprise,
or sexual arousal.
The Name Effect
1/3 of subjects report hearing their own name when it
is embedded in the unattended message (Moray,
1959).
A limited amount of meaning processing is
apparently possible for information that is supposed
to have been filtered out.
This is inconsistent with Broadbent’s idea.
22
23
Treisman’s Theory
Treisman proposed a theory in which the filter
reduces or attenuates (but does not completely
block) the analysis of the unattended information.
Stimulus analysis proceeds in a hierarchy starting
with analysis of physical features, syllables,
letters, words, grammar, and meaning. If
cognitive capacity is overloaded, the later stages
of analysis are omitted.
Detection thresholds of stimuli consistent with
the current goals are lowered.
Anne
Treisman
Treisman’s Attenuation Theory
24
25
26
Two Major Differences
27
1. Broadbent suggests that there is an attentional filter very early in
the processing stream, which filters out stimuli based on physical
characteristics. Treisman suggests that there is an attenuator that
gives processing preference to stimulus based on what we are
trying to do at the moment. Each stimulus has a different activation
threshold. Attention is goal directed.
2. Broadbent suggests that the filter blocks out all unattended stimuli.
The unattended stimuli do not receive any processing if attentional
capacity is overloaded. Treisman suggests that the attenuator does
not block out processing, it simply gives preference to the attended
stimuli. If there is enough cognitive resources, the unattended
stimuli can get processed, too.
Visual Attention
35
Much more research on attention is done on visual
attention.
Compare with auditory stimulus, we have more
control on the way visual stimuli are presented
(presentation duration. etc.), and we have many more
ways to vary a visual stimulus (color, shape,
orientation, etc).
36
Mack and Rock (1998) asked subjects to judge whether
the length of the horizontal line or the vertical line is
longer in a + sign. The entire display was then replaced
by a pattern mask.
Subjects must focus on a fixation at the center of the
screen and not look directly at the + sign when it
appears (200ms).
Here is an example...
Inattentional Blindness
During the 4th trial, the fixation changed to a triangle, a square, or
a cross.
89% of the subjects failed to notice the change!
Is 200ms just too fast for people to see the change?
No, because when subjects were told they should report any other
stimuli that appeared on the screen before they started the task,
over 90% of them notice the change.
Inattentional blindness cannot be attributed to a fast presentation
rate.
55
56
From these results, Mack and Rock claimed that
“there is no perception without attention.”
Is this true?
Moore and Egeth (1997) showed subjects pictures
that contained white and black dots with two
horizontal lines around the center of the screen.
Participants job was to ignore the dots and judge
which line was longer.
57
In the first three trials, the display looked like this.
Two lines with a haphazard series of dots
surrounding them.
58
On the fourth trial, the dots, together with the two lines,
form the Muller-Lyer illusion.
59
When subjects were asked if they had noticed
any pattern in the dots, none reported seeing
the pattern.
Subjects couldn’t even pick the correct pattern
out of four.
Cathleen
Moore
However, remarkably, results from the line
length judgment task showed that indeed the
dot pattern was processed -- because 95% of
the subjects reported that the top line was
longer!
Howard
Egeth
Do you really not perceive the
unattended information?
60
You go home, open the door with your keys, put the keys
down somewhere, and later you realize...
Oh X&%#@!! I forgot where I left my keys!
Should inattentional blindness be characterized as
inattentional amnesia instead?
61
Inattentional blindness =
Inattentional amnesia
but...
Inattentional amnesia ≠
Inattentional blindness
Inattentional Blindness or
Inattentional Amnesia?
62
Rees, Russell, Frith and Driver (1999) provided an answer
to this question using neuroimaging methods.
They showed subjects a picture superimposed on a letter
string. The letter string is either a word or a nonword, and
activations may involve all the corresponding
subjects must pay attention
to either the picture or the
word-related processes. Note that word-related other
activations
were found here for attended
letter string and ignore the
stimulus.
letter streams, even though our repetitiondetection task did not require participants to
treat words any differently from nonwords. In
this respect, our results agree with previous
imaging studies that similarly found wordrelated activations even in nonlexical tasks
(13).
Those studies argued on that basis that
word processing takes place automatically, as
many psychological accounts have proposed
(2, 7, 21). However, these data argue against
fully automatic word processing for the new
situation in which the letter streams were
unattended, with the pictures being attended
instead. The critical interaction between
which stream was attended and whether
Rees, Russell, Frith, & Driver (1999)
When Ss attend to the
letter string, the brain
activity associated with
it is very different for
words vs. nonwords,
which is to be expected.
REPORTS
words were presented (that is, testing for a
larger effect of words minus consonants
when the letter stream was attended) revealed
robust left-hemisphere activations virtually
identical to those for the simple effect of
words when attended (Fig. 2, C and B).
Moreover, comparing the same stimuli as
before (that is, meaningful words minus consonant strings), but with the letter stream
unattended, did not activate a single voxel in
these cortical areas, neither in the group analysis (18) nor in further analyses of individual
participants at low threshold (22). The timecourse data for attended words versus conso-
63
A
CLOCK
Picture stream target
0ms
CLOCK
500ms
But what happens when
Ss were attending to the
pictures?
NSFHT
B
80
word recognition
1000ms
40
Fig. 2. (A) Effects of attention on fMRI activity. Three views of a T1-weighted anatomical template
in Talairach space, on which are superimposed areas where attention to the picture stream
produced significant activation compared with all letter streams (green) or vice versa (attend letter
streams minus picture stream; red). (B) Simple effect of words compared with consonants when
attending letters. Three anatomical views, on which are superimposed in red those areas where
words minus consonants produced significant activation when attention was directed to the letter
stream (see also left half of Table 1). (C) Interaction between attention and word processing. Three
anatomical views on which those areas where evoked activity specifically reflected the critical
interaction between attention and word identity (where the effect of words minus consonants was
that word processingAis not merely
(13). However, unlike this experiment, those
taxing demands of the picture task establishCLOCK
ted but is abolished Picture
whenstream
attention
studies
presented individual words in total
ing conditions of full inattention for the
target
y withdrawn. If unattended words
isolation, for up to 1 s, so the lexical properwords (27). Under conditions that do not
0ms
d only from inattentional amnesia
ties of the stimulus were unlikely to be igfully engage attention, incidental processing
CLOCK
differential response to words vernored. Our study shows that the basal tempoof linguistic properties
may take place even
64
nsonant strings should have been
ral500ms
activation for words can be eliminated
during nonlexical tasks. Indeed, as in previt the time they were presented
even
under conditions of true inattention.
ous studies of word processing, which preNSFHT
nattended because of automatic proThe activations for attended words in left
sented letter strings in total isolation (13),
. By contrast, if ignored words suf-1000msprefrontal cortex (Fig. 2B), close to Broca’s
words in the attended stream produced lexical
inattentional blindness, the differarea, have also been observed in previous
activations here despite the nonlexical nature
(A) Effects
of attention on(12),
fMRI activity.
views of a T1-weighted
anatomical
template were
esponse that is observed for words
imaging studies Fig.
of 2.word
processing
of Three
our repetition
task. These
activations
in Talairach space, on which are superimposed areas where attention to the picture stream
B 80
ttended should be completely
elimwhere a role forproduced
this area
in activation
phonological
eliminated
only(green)
when
the versa
picture
stream
significant
compared with
all letter streams
or vice
(attend
letter was
streamsIn
minus
picture
stream;
effectattended
of words compared
when were
when they are unattended. Our reretrieval and semantics
was
suggested.
We(B) Simple
being
insteadwith
andconsonants
the words
No.
fact,
from
thered).
recognition
attending letters. Three anatomical views, on which are superimposed in red those areas where
upport the latter prediction. When
also found activations
for
attended
words significant
inno ignored.
Although
words minus
consonants
produced
activation when
attentionunattended
was directed towords
the lettermight
data,
Ss have
absolutely
stream (see also left half of Table 1). (C) Interaction between attention and word processing. Three
attention was directed to other maseveral areas of memory
left parietal
cortex
and a words
be processed
to a greater extent under condianatomical views
on which
those areas where
evoked activity specifically reflected the critical
of the
unattended
betweenEnhanced
attention and acword identity
effect of words
minus consonants
was the
or a demanding task, even
words
homologous areainteraction
on the right.
tions(where
thatthe impose
a lower
load than
40
greater
during attentionAmnesia!
to the letter streams than during attention to the picture stream) are
-Inattentional
ed directly at the fovea produced no
tivity in left parietal cortex for words has
present demanding picture task (28) or that
Percent 'yes' in word recognition
Do people remember the
unattended words?
superimposed in red.
ble differential cortical activity
previously been associated with orthographic
use only a single stream of stimuli (29), our
1. Coordinates
z scoresword
for activation
related tosuggest
word processing.
are loci
higher
ever (Fig. 3). Differential activation
to phonological Table
conversion
andandwith
results
that,Shown
under
thewithappropriate
activity for words versus consonants when attention was directed to the letter stream (left columns) and
rds compared with consonants was
meaning in a distributed
system
conditions
of true
inattention,
can be
loci where
suchsemantic
word-related
activity
was greater
during attention
to the
letter stream words
than during
Words
that
subjects
haven’t
0
attention
to the picture
columns).directly
Coordinates
shown arebut
for the
ither in classic language areas
nor inUnattended
(25). Again,
our data
suggest
that stream
such (right
activfixated
notmaxima
read.within each area
Attended
Foils
seen
the
experiment
of activation
(P ! in
0.05;
corrected
for multiple comparisons except where a different corrected value is
a of visual cortex when
ity may
obliterated
under
conditions of full
Fig. 1.unattended
(A) Schematic illustration
of be
stimulus
specifically
indicated).
configuration [see (10) for inattention.
details]. (B) Perfor).
mancewords
in theminus
surprise
esting for a
before (that is, meaningful
con- recognition memory test
Interaction of words and
words minusReferences
consonants
posteriorsonant
basal
temporal
OurBarimaging
results imply true Attended
inattenwords
[see (16)
graph
and Notes attention
consonants
strings),
butforwith
theactivation
letter
streamfor procedure].
and standard
deed) revealed
unattended,
notshows
activateinterparticipant
awords
single voxel
in mean
1. W. A. Johnston and V. J. Dark, Annu. Rev. Psychol. 37,
Cortical
region words in the
g.
2B) found
for didattended
has
tional
blindness
for
ignored
ns virtually
these cortical areas,viation
neither inofthepercent
group anal“yes” responses when judg43 (1986); H. E. Pashler,
The Psychology of Attention
Talairach
z score
z score
e effect of in ysis
(18) nor in imaging
further
of individual
served
previous
studies
ofhad been
following
We do not suggestTalairach
that our
ing analyses
whether
a word
shown insense.
the
coordinates (mm)
coordinates
(mm)
(MIT Press, Cambridge,
MA, 1998).
C and B).
participants at low imaging
threshold (22).
The
time-experiment. Attended and
of the
ocessing
topart
this
area
participants were blind to the presence of
2. C. MacLeod, Psychol. Bull. 109, 163 (1991).
stimuli as (13,
course 22).
data forLesions
attended
words
versus
consounattended
words
refer to physically equivaLeft inferior frontal
"39
6
27
4.70 (P # 0.09)
"39
6
27
4.41
displays(24).
but with
directed
to the
3. D. Holender, Behav. Brain Sci. 9, 1 (1996).
duce alexia or visual lent
anomia
Aattention
letters
(26)
when (BA44)
they were attending the
65
letter stream and to the picture stream, respec4.
C.
Cherry,
On
Human
Communication
(Wiley,
LonLeft
posterior
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"51
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5.71
tudy showed that words
activate
this
superimposed
pictures,
but
rather
they
were
Inattentional
tively.
Foils refer to wordsBlindness
that were never or Inattentional Amnesia?
"39 Perception
"24
4.85Commudon, 1957); D. E. "42
Broadbent,
and
4.59
"33London,
"33 1958).
57
5.36
nication
(Pergamon,
4.49 (P # 0.06)
"24
"75
42
6.50
5. J. Lewis, J. Exp. Psychol.
85, 225 (1970).
"30
"57
39
5.57
Attend
Pictures:
6.
S.
P.
Tipper
and
J.
Driver,
Mem.
Cogn.
16,
64 (1988).
Right posterior
36
"63
24
4.23 (P # 0.17)
36
"60
33
5.32
Left frontal cortex
parietal (BA7)
7. J. Deutsch and D. Deutsch, Psychol. Rev. 70, 80
(1963).
terior basal temporal corWords
Words
8. M. Corbetta, F. M. Miezin, S. Dobmeyer, G. L. Shuler). All four panels use the
Letters
Letters
www.sciencemag.org SCIENCE VOL 286 24 DECEMBER
2505
man,1999
S. E. Petersen, Science 248, 1556 (1990);
D. C.
otting conventions. AverSomers, A. M. Dale, A. E. Seiffert, R. B. H. Tootell, Proc.
D contrast evoked at each
z
Natl. Acad. Sci. U.S.A. 4, 1663 (1999); A. Martinez et
ee Table 1 for coordinates)
al., Nat. Neurosci. 2, 364 (1999); S. Treue and C. M.
ed as a function of time,
Trujillo, Nature 399, 575 (1999).
ng across epochs and par9. J. Driver and J. D. Mattingley, Curr. Opin. Neurobiol.
. Note that the areas
5, 191 (1995).
time courses are shown
10. Six right-handed participants (two male and four
30
60
30
60
0
0
entified as those areas
female; 23 to 29 years old) gave informed consent to
Time
Time
participate. Displays like those in Fig. 1 were presenta maximal simple main
Attend Letter-strings:
Attend Pictures:
ed every 500 ms for 250 ms. All pictures belonged to
words under attention to
Left temporal cortex
Left temporal cortex
the Snodgrass-Vanderwart set [ J. G. Snodgrass and
Unshaded areas represent
M. Vanderwart, J. Exp. Psychol. Hum. Learn. Mem. 6,
Words
Words
MRI activity.
of a T1-weighted anatomical template
quired
inThree
theviews
experimental
When
Ss attend
to theLetters
picture, the differences in brain
activity 174 (1980)]. Superimposed on the pictures were
superimposed areas where attention
to the picture
stream
Letters
ns [see
(11)]
and
mpared
with (10)
all letterand
streams
(green)
or vice versa (attend letter
strings of five letters, comprising either random conbetween
the
). (B) Simple
effect of words
compared
with consonants
whenwords and nonwords disappear!
areas
represent
those
acsonants or high-frequency concrete nouns. Total
al views, on which are superimposed in red those areas where
significantthe
activation
when attention
was directed to the letter
uring
passive
fixation
stimulus size was about 5°, centered at fixation. In
). (C) Interaction between attention and word processing. Three
Error
in- reflected the critical
different scanning epochs, the letter stream included
areas
wherebars
evoked indicate
activity specifically
word
identity
(where
the
effect
of
words
minus
consonants
was
either letter strings alone or 60% concrete nouns
ipant standard error and
tter streams than during attention to the picture stream) are
mixed with letter strings. When words were present,
ale bar represents 0.5%
they were introduced only after the first eight items,
signal change. Activity
as previous work has shown that people notice disr activation related to word processing. Shown are loci with higher
when
thewas letter
60
30
60
0 and 30
0
when
attention
directed to stream
the letter stream (left columns)
tractors more at the beginning of a stream [A. M.
ty
was
greater
during
attention
to
the
letter
stream
than
during
Time
Time
edcolumns).
meaningful
words is
Treisman, R. Squire, J. Green, Mem. Cogn. 2, 641
Coordinates shown are for the maxima within each area
with
squares
anda different
a
r multipleblack
comparisons
except where
corrected value is
(1974)]. Participants performed a single task while
e, and activity when the same stream included only meaningless letter strings is plotted with
they underwent brain imaging (11), detecting immeand a dotted line.
diate repetitions of stimuli within whichever stream
Interaction of words and
BOLD contrast
BOLD contrast
BOLD contrast
temporal (BA37)
Left posterior
parietal (BA7/40)
BOLD contrast
presented to a particular participant before,
thus providing a measure of the tendency to
answer falsely in the affirmative. Participants
Time course of foci of acAttend
Letter-strings:
recognized almost
all the
attended words but
Leftunattended
frontal cortex
did not differentiate
words from
left frontal (upper) and
foils they had never seen before.
"33
"27
"33
"72
57
33
66
d words minus consonants
es (mm)
z score
6
27
6
"24
3
2
57
33
4.59
4.49 (P # 0.06)
3
24
4.23 (P # 0.17)
4.70 (P # 0.09)
"39
4.63
"51
"42
"33
"24
"30
36
24 DECEMBER 1999
“These
results demonstrate true inattentional
attention
blindness
score for words and show that visual
24z DECEMBER
1999 VOL 286 SCIENCE www.sciencemag.org
6
27
4.41
recognition
wholly depends on attention even
"51
5.71
for"18
highly
familiar and meaningful stimuli at the
"39
"24
4.85
"33
57
5.36
"75
42
6.50
center
of
gaze.”
"57
39
5.57
Talairach
coordinates (mm)
"60
!
33
5.32
2505
Rees et al., 1999 Science
Change Blindness
Change blindness refers to an observer’s remarkable
inability to detect changes in scenes they are looking
at.
Apparently, there are large gaps in what we see. Our
perception of any visual scene is far from complete.
These results underscore the active nature of
perception. We must expand some effort to see what
we need to see.
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