Top-down influences on the
time-course of visual attention:
When the attentional blink
meets word superiority effect
Maria V. Falikman
Lomonosov Moscow University
Research supported by the Russian Fund
for Basic Researches, grant # 03-06-80191
Where cognitive science was born…
“… I went away from the
symposium with the strong
conviction, more intuitive than
rational, that human experimental
psychology, theoretical linguistics,
and computer simulation of
cognitive processes were all part
of a larger whole...”
(George Miller on the
1956 MIT Symposium)
Types of processing (information flow)
Task,
Experience
Top-down (conceptually-driven)
Conscious
percept
Bottom-up (data-driven)
Stimulus
Top-down influences
on visual attention
Unconscious (implicit)
Conscious (explicit)
Context-based
or
memory-based
Goal-directed
or
task-dependent
Contextual cueing
Priming (+/-)
Schemata
...
Strategic regulation of
perceptual task
accomplishment
Rapid Serial Visual Presentation
(RSVP)
RA
PI O
U
R
N
V
P
S
E
A
T
L
I
DS
E
RI
AL
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
AL
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
ER
IA
L
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
AL
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
ER
IA
L
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
AL
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
ER
IA
L
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
AL
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
ER
IA
L
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
AL
The Attentional Blink (AB)
under RSVP conditions
RA
PI
DS
ER
IA
L
The AB effect replicated: Results of the standard
dual-task RSVP experiment (2000)
100
Experimental
condition
% Correct Reports
80
Control
condition
60
40
20
0
0
1
2
3
4
5
Probe relative serial position
6
Why a blink?
Blindness!
Hybrid
models Perceptual
Amnesia!
system
Object reconfiguration
substitution
Central
theory
interference
theory
Two-stage
model
Attentional
dwell-time
Interference
theory
Attentional model
gate model
Models of selective attention and models of its blink
Early selection / filter
Attentional gate
(Broadbent, 1958)
(Raymond et al, 1992)
Late selection
Interference model
(Deutsch & Deutsch, 1963)
(Shapiro et al, 1994)
Pertinence model
Two-stage model
(Norman, 1968)
(Chun & Potter, 1995)
Multiple selection
“Smart selection”
(Johnston & Heinz, 1979)
(Shapiro & Luck, 1999)
Flexible selection
(Yantis & Johnston, 1990)
“Intelligent filtering
system”(Enns et al, 2001)
Perceptual cycle
Reentrant model
(Neisser, 1976)
(Di Lollo et al, 2000)
Quo vadis?
Attention for action
D.A. Allport
O. Neumann
A.H.C. van der Heijden
Attention as an
aspect of action
Gippenreiter, 1983 [rus]
1986
or
a set of
“task-related
mechanisms” (e.g. Deacon
& Shelley-Tremblay, 2000)
The prototypical “bottleneck” model
T1
Early stage
T2
LC-stage
Early stage
T1 report
...
LC-stage
T2
The AB effect: my old results again
100
Experimental
condition
% Correct Reports
80
Control
condition
60
40
20
0
0
1
2
3
4
5
Probe relative serial position
6
The AB effect might be due to the inability of
perceptual system to obtain further information
until the previous goal-directed act (conscious
target identification) is completed.
Then, the AB could be modulated through the
change of the size of the observer’s activity “units”:
if we incorporate the 1st target into a larger
perceptual “object”, the AB will probably not
interrupt perception until the end of the act.
“The difficulty is not to combine stimuli, but rather to deal with
them independently at the same time... capacity limits occur
where stimuli have to be kept apart, not where they have to be
combined…”
(Neumann, 1987, p.363)
“Attentional units”
larger than letters?
W
O
R
D
S
Stimuli examples:
Russian letters
PRINTED
WRITTEN
The word superiority effect
Better performance on letters within a word
than on random letters:
• faster recognition
• more letters perceived within a brief (10 ms) presentation
“I find it takes about twice as long to read (aloud, as
fast as possible) words which have no connexion as
words which make sentences, and letters which have
no connexions as letters which make words. When
the words make sentences and the letters words, not
only do the processes of seeing and naming overlap,
but by one mental effort the subject can recognize a
whole group of words or letters, and by one will-act
choose the motions to be made in naming them, so
that the rate at which the words and letters are read
is really only limited by the maximum rapidity at which
the speech organs can be moved...”
(Cattell, 1886, p.64).
The word superiority effect
Further explorations:
Reicher, 1969
Wheeler, 1970
McClelland, 1976
...
The word superiority effect
R
The word superiority effect
WOR D
The word superiority effect
WOR D
Some examples of “mutable” words
(main experimental session)
I
...S
…W A
P T
R E
I R
T #
E #
L
…F AI VL O RT #
...P
G
...B
…B RR II DD EG #E #
Hypothesis
IF
the AB is due to a certain bottom-up controlled
limitation (“a bottleneck”),
it will leave its signature on the observers’
performance on mutable words.
IF
it is rather shaped by top-down processes in
the information processing system,
it will either disappear or be diminished in the
word-reading task.
Comparison of correct reports on separate letters in
mutable words and on a probe X under “standard”
AB conditions (2000)
100
Dual task
(probe X)
Single task
(probe X)
Mutable
words
% Correct Reports
80
60
40
Word
identification
point?
20
0
1
2
3
4
5
Probe relative serial position
6
There is a blink on mutable words!
Individual differences.
100
Subject 6
% Correct Reports
80
Subject 17
60
Mean
40
20
0
1
2
3
4
Probe relative serial position
5
And what about the overall result?
100
% Correct Reports
80
Mentioning
a position
for all word
strings
60
40
20
0
1
2
3
4
Probe relative serial position
5
The ACTUAL experimental design:
Preceding
control
session:
identify the type
of a white letter
and name three
letters following
it (after
Weichselgartner
& Sperling,
1987)
Main
experimental
session:
identify the type
of a white letter
and read a word
beginning with
this letter
Concluding
control
session:
identify the type
of a white letter
and name three
letters following
it (after
Weichselgartner
& Sperling,
1987)
Strategic change: Results of framing sessions
50
Report probability, %
45
Preceeding
session
40
35
Concluding
session
30
25
20
15
10
5
0
1
2
3
4
5
Relative serial position
6
80
80
70
70
Report probability, %
Report probability, %
There could be no strategic changes!
Individual differences again.
60
50
40
30
20
10
60
50
40
30
20
10
0
0
1
2
3
4
5
Relative serial position
Subject 16
6
1
2
3
4
5
Relative serial position
Subject 2
6
Control experiment: No practice effects
50
Preceeding
session
Report probability, %
45
40
35
Concluding
session
30
25
20
15
No words
noticed
between!
10
5
0
1
2
3
4
5
Relative serial position
6
Word superiority in written vs. printed T1 task
T1 type
identification
in the
preceding
control
session:
89  3.9%
T1 type
identification
in the wordreading
session:
96.2  2.4 %
Significant!
(p<0.0001)
T1 type
identification
in the
concluding
control
session:
90.4  2.9%
Significant!
(p<0.0001)
Subjective dual-task estimation through
the experimental sessions (% of subjects)
Preceding
session
Main session
(wordreading)
Two separate tasks
Concluding
session
A single whole
The AB seems to depend on the task
and on subjective strategies.
But strategies serve for achieving a goal,
and
the goal is to report on T1 etc.
For that, verbal working memory consolidation
or encoding is essential!
Working memory consolidation:
neurophysiological data
P300 - a late ERP component, a correlate of working
memory encoding and attentional load
T2: suppressed for
missed probes during
the AB (Vogel et al, 1998;
see also Rolke et al, 2001)
T1: repeats the dynamics
of the AB after T1
identification (McArthur et
al, 1999)
A possible model: two-stage compatible
...
P ...
P
P
H
H
T1 WM encoding...
...
P R
R
Not yet!
P
A
H
H
A R
T1 + “word”
WM encoding
Report
S
E
Time to start WM encoding:
- I got the word!
- My VSTM buffer is full!
Conclusions
 Perceptual task accomplishment can in
principle be organized in such a way, that,
given a sufficient load of that limited-capacity
block or process, the AB would either
disappear or diminish and shift from its critical
temporal interval.
 These changes can be determined both
externally
(by
task
conditions
and
requirements) and internally (by subjective
strategy), that is characteristic for any human
activity.
Hurrah!
Recent results working for this hypothesis:
if T1 is an addition task (e.g. 2+3)
and T2 is an answer
(seems to be… 5!)
there is no blink!
(Kunar & Shapiro, in preparation)
Conclusions
 Our results directly suggest that the
attentional blink deficit does not represent
merely the workings of a fixed capacity-limited
mechanism for the perception of events
occurring over time, but rather the structure of
actions a subject has to perform in order to
accomplish a given task.
Missing controls?
 Pronounceable pseudowords
- in progress
 Random strings, instruct to read words
- in progress
 Words with ambiguous endings?
- Thanks to Molly Potter for the brilliant idea!
To be performed.
 More ideas?
- Please keep them in mind until
the discussion...
Prospect:
 Visual search?
 Attentional switching (gating paradigm)?
 Metacontrast masking?
 Unconscious perceptual priming?
 Crowding? - YES (Fine, in press)
Special thanks to
Dr. Valeriy Romanov,
Dr. Yuriy Dormashev
(Moscow University)
for inspiration of the AB research
Ekaterina Pechenkova
(Moscow University)
for collaboration and
invaluable discussions
Our programmers:
Suren Sagiyan
George Kouryachy
Thank you for your attention
that hopefully didn’t blink
(owing to the top-down regulation!)