Transcript Decreasing Visual Subitising Performance with Age

Poster #890
THE SMITH–KETTLEWELL
SKERI
Decreasing Visual Subitising Performance with Age
Maya Kumar1, Roger Li1,2, Dennis Levi1,2, Sandy Chat1, & Manfred MacKeben3
1School
of Optometry & 2Helen Wills Neuroscience Institute,
University of California-Berkeley, Berkeley, California, USA
3The Smith-Kettlewell Eye Research Institute, San Francisco, California, USA
Results
Summary & Conclusions
• Visual subitising is the ability to quickly and intuitively
enumerate small numbers of items, is hypothesized to
be mediated by parallel processing.
Aging and Subitising
•
Older people have problems processing multiple
objects at a time.
•
Subitising, the quick assessment of small numbers of
stimulus elements, is achieved through parallel
processing. Such mechanisms are important where
ever speed counts, e.g. in mobility and obstacle
avoidance..
•
Visual subitising performance deteriorates with
advancing age.
•
Mean subitising thresholds: Systematically decreased
from 7.1 (21-30) to 4.8 dots (61-90) across the 5 age
groups.
•
Roughly, 50% of the loss in threshold occurred by the
age of 62.
•
The response latency (61-90) was prolonged an
average of ~ 30% (the latency curve shifted upward
for 1 - 7 dots).
•
For all age groups, the mean number of dots reported
was very close to the number of dots displayed on the
screen.
•
The loss in subitising performance cannot be
explained by the optical changes.
•
Subitising threshold (21-40-yr-old) was minimally
affected by reduced retinal illumination (0.2 log unit)
and optical blurring (with ‘plus’ lens ~20/20).
•
After training, the performance (67-yr-old) was still
worse when compared with 21-30 group
•
With longer stimulus durations, counting performance
(67-86-yr-old) could be improved to reach young
adult level.
• To understand how optical and neural changes with
age1 affect visual performance
Methods
10
F(4,78) =8.3
P < 0.0001
8
Threshold (dots)
• To examine any age-related variations in visual
subitising performance.
Mean threshold (dots)
10
6
4
2
0
•
•
•
•
•
•
>6
0
21
-3
0
31
-4
0
41
-5
0
51
-6
0
Normal macula, no lens & vitreous opacities …
Visual acuity: 20/20 or better
Age group
(yrs)
Sample
size
Gender
(M)
Gender
(F)
Mean age
(yrs)
SD
(yrs)
21-30
19
9
10
22.7
2.6
31-40
17
10
7
34.2
2.8
41-50
13
7
6
44.6
3.3
51-60
17
7
10
55.3
3.5
60-90
17
5
12
70.6
7.1
60
21-30
31-40
41-50
51-60
> 60
40
20
0
0
2
4
6
8
10
Mean number of dots reported
Mean hit rate (%)
Task: To enumerate the number of dots as quickly &
accurately as they could
Response latency: the time it took to say the number into
a microphone
On each trial, a number (1-10) of black dots was presented
on the monitor screen for 200 ms.
Dot diameter: 3 arcmin
Randomly positioned in a 10 x 10 square (1◦ x 1◦)
Minimum dot distance ≥ 9’ (edge-to-edge)
Threshold: Midway between the upper & lower asymptotes
of a Weibull psychometric function.2
400 trials
Viewing was binocular
Subjects
•
•
40
60
80
0
2
4
6
8
10
Number of dots
10
21-30
31-40
41-50
51-60
> 60
8
6
4
2
0
0
2
4
6
8
10
Number of dots
Number of dots
Optical or Neural?
Reduced Ret. Illumination
Optical blurring to 20/20
10
Slow Learning
Stimulus Duration
Opt. blur (20/20)
RI: ND filter (0.2)
KG (67)
21-30
8
6
4
2
0
5
10
Threshold (dots)
KG (67)
CB (74)
MD (86)
21-30
10
10
Age: 21-40
n=5
Threshold (dots)
•
100
80
Threshold (dots)
•
2
21-30
31-40
41-50
51-60
21-60
61-85
Age (years)
Control threshold (dots)
•
4
1000
Age (years)
Mask
200
6
20
100
Duration (ms)
8
0
Visual Stimulus
Target
Mean response latency (ms)
Purpose
8
Acknowledgements
2
3
4
5
Session
6
7
The authors thank Jenny Sung for her help with
collecting data.
•
Research grants : NIH NEI R01EY01728 (DL) &
The Smith-Kettlewell Eye Research Institute (MM)
6
4
2
References
0
1
•
100
1000
Stimulus duration (ms)
1. Li RW, Edwards MH, Brown B. Vis. Res. 2000; 40: 3775-3781.
2. Sharma V, Levi DM, Klein SA. Nat. Neurosci. 2000; 3: 496-501.