Post on 07-Aug-2018
transcript
Subitizing sets and set-based selection:
Early visual features determine what countsJustin Halberda, The Johns Hopkins University
Introduction
Halberda, Sires & Feigenson (2006) found that approximately
three spatially-overlapping sets can be attended, enumerated,
and stored in parallel. When briefly shown dot arrays adults canapproximate the total number of dots, the # of reds & the # of
blues (3 sets in parallel). This motivates the following questions:
1) Do sets function as individuals for attention?
2) Is there a visual continuum between individual items and sets?
3) Which features support set selection?
Question 1: Do sets function as individuals
for subitizing?! Adults (N=12) attempted both data-limited (% correct) and free-
viewing (RT) subitizing of individual dots and colored sets.
Answer: Yes
dots
Dots (1-8) Sets (1-8)How many dots? VS How many colors?
Question 2: Is there a visual
continuum between dots and sets?
“I can’t remember.
Which one is the pizer?”
Answer: Yes
C
h
i
ld
re
n
p
e
rf
o
r
m
ed
b
e
tt
e
r
o
np
o
s
t
te
s
t
t
ri
a
l
s
of
w
o
rd
k
n
o
wl
e
d
g
ew
h
e
n
th
e
n
o
ve
l
o
bj
e
c
t
ha
d
a
p
p
e
a
r
e
d
d
u
r
i
n
g
t
r
a
i
n
i
n
g
i
n
a
n
I
n
f
e
r
e
n
c
e
t
r
i
a
l
t
h
a
n
i
n
a
n
I
n
s
t
r
u
c
t
i
o
n
t
r
i
a
l
.
S
u
r
p
r
i
s
i
n
g
l
y
,
c
h
i
l
d
r
e
n
l
o
o
k
e
d
l
o
n
g
e
r
a
t
t
h
e
I
n
s
t
r
u
c
t
i
o
n
n
o
v
e
l
t
a
r
g
e
t
o
b
j
e
c
t
s
t
h
a
n
t
h
e
I
n
f
e
r
e
n
c
e
n
o
v
e
l
t
a
r
g
e
t
o
b
j
e
c
t
s
,
h
o
w
e
v
e
r
t
h
e
y
w
e
r
e
m
o
r
e
a
c
c
u
r
a
t
e
a
t
r
e
c
a
l
l
i
n
g
t
h
e
I
n
f
e
r
e
n
c
e
n
o
v
e
l
t
a
r
g
e
t
o
b
j
e
c
t
s
.
S
u
c
c
e
s
s
a
t
t
h
e
t
a
s
k
i
n
b
o
t
h
l
e
a
r
n
i
n
g
c
o
n
t
e
x
t
s
d
e
m
o
n
s
t
r
a
t
e
s
c
h
i
l
d
r
e
n
’
s
u
n
d
e
r
s
t
a
n
d
i
n
g
o
f
t
h
e
r
e
l
a
t
i
o
n
s
h
i
p
b
e
t
w
e
e
n
t
h
e
2
-
D
a
n
d
3
-
D
r
e
p
r
e
s
e
n
t
a
t
i
o
n
s
o
f
e
a
c
h
n
o
v
e
l
o
b
j
e
c
t
.
“I can’t remember.
Which one is the dax?”
I
nf
e
r
e
n
c
e
I
n
s
t
r
u
c
t
i
o
n
ReferenceHalberda, J., Sires, S. F. & Feigenson, L. (2006). Multiple spatially overlapping sets
can be enumerated in parallel. Psychological Science, 17(7), 572-576.,
Discussion
General Discussion• An entire set of items function as a single individualfor attention as evidenced by subitizing of sets and
early feature-based selection
I
n
f
e
r
e
n
c
e
I
n
s
t
r
u
c
t
i
o
n
I
n
f
e
r
e
n
c
e
I
n
s
t
r
u
c
t
i
o
n
Subitizing individual
dots and subitizing
sets may draw on acommon mechanism
as indicated by
significant correlations
across these blocks as
a function of # oftargets
Question 3: Which features support
set selection?
R
e
al
O
b
j
ec
t
P
o
st
T
e
s
t
Answer:
G34 803
VSS, 2007
Ready
Screen
Target
1000ms
Screen 1
250ms
Screen 2
250ms
Response
0
20
40
60
80
100
1 2 3 4 5 6 7 8
Number Of Colors
0
2000
4000
6000
8000
Response T
ime (
ms)
0
20
40
60
80
100
Percent E
xactly
Correct
0
20
40
60
80
100
Percent
Exactly C
orrect
0
20
40
60
80
100
1 2 3 4 5 6 7 8
Number Of Colors
0
1000
2000
3000
Re
sp
on
se
Tim
e (
ms)
! Adults can subitize setssets
1 2 3 4 5 6 7 8
0
25
50
75
100
0
2250
4500
6750
9000
1 2 3 4 5 6 7 8
RT (
ms)
1 2 3 4 5 6 7 8
0
25
50
75
100
Complete Overlap
Some Overlap
No Overlap
Single Dots
Pe
rce
nt
Exa
ctly C
orr
ect
Number Of Colors
Limited-Viewing Free-Viewing
! Adults (N=12) attempted both data-limited (% correct)
and free-viewing (RT) subitizing of four display types
! Tthese four display types varied the spread of thesubsets (how distributed the sets are) and the distance
between the centroids of the subsets
! The centroid may represent the position of a set in
space and therefore separation in centroids may be
crucial for subitizing
+ = Centroid O = Spread
++ +
+
+
+
++
+
Complete
Overlap
Some
Overlap
No
Overlap
Single
Dots
Size
Gabor
Color
Curvature
Orientation
Vernier
ConjunctionShape
Target Target
The usual
suspects
40
50
60
70
80
90
100
Perc
ent
Corr
ect
±SE (
chance=
50%
)
Siz
e
Gab
or
Co
lor
Cu
rva
ture
Ori
en
tati
on
Ve
rnie
r
Co
nju
nc
tio
n
Sh
ap
e
! Adults (N=12)enumerated a target set
among distractors
! Task: Which screen
(1st or 2nd) has moretargets?
! Subitizing capacity increased smoothly up to a level of
3-4 subsets in parallel as a function of increasing
centroid distance and decreasing spread
1 3 5 1 3 5
R2 = 0.414
R2 = 0.4893
R2 = 0.0774
R2 = 0.1434
R2 = 0.1555
R2 = 0.149
R2 = 0.118
R2 = 0.0972
0
1000
2000
3000
4000
5000
6000
7000
8000
0 1000 2000 3000
Subject RTs For Individual Dots (ms)
Subje
ct
RTs F
or
Colo
red S
ets
(m
s)
Answer = 1
Answer = 2
Answer = 3
Answer = 4
Answer = 5
Answer = 6
Answer = 7
Answer = 8