In this study we examined two types of information Enumeration of Objects and Identifying of Objects

1. Identifying
vs.
Enumerating
Objects
John L. Dennis & Vidal Annan
Visual Attention Lab
Rutgers University Center
for Cognitive Science

2. Theoretical Motivation
• The FINST mechanism has been
described as a limited-capacity parallel
mechanism for object individuation of
about 4-5 objects, (Pylyshyn & Storm,
1988).
• This mechanism has been used to
describe some preconceptual processes,
i.e., MOT and subitizing.

3. General Question
What “types” of information
about objects are accessible
when they are processed in
parallel, i.e., shape, orientation,
color, position or quantity?

4. Research Question
In this study we examined two
types of information –
Enumeration of Objects
and
Identifying of Objects

5. Screen Shot
Screen 1 Screen 2

6. Design
• A total of 16 objects were present on the screen
for all trials. A subset of 2-8, of these (the
“targets”) were a different color from the rest of
the objects (they were either red or green), and
color information was present for 300 ms before
they changed to a neutral gray.
• Observers were instructed to count the number
of objects of the specified color as fast as
possible.
• After the observer indicates how many targets
there were, they selected the targets by clicking
on the objects that had been the target color.

7. Identification
vs.
Enumeration

8. Results
There is an overall significant
difference between enumeration
and object identification
[F(1, 11) = 27.437, p < .001]

9. But when does the performance
on the two tasks diverge?

10. Point of Divergence
This divergence between identifying
and enumerating fails to occur for the
quantities 2, 3, 4
[F(1, 11) = .047, p = .832]
and does occur when we include the
quantity 5, (i.e., when we compare the
effect for 2, 3, 4 and 2, 3, 4, 5)
[F(1,11) = 6.61, p = .026]

11. Possible Confound
• What if the difference between the
performance on enumeration and
identification of target objects was to
due to the the interference between the
two tasks.
• The same observers responded to trials
where they were asked to select or to
enumerate separately.

12. Enumerate Alone

13. Identification Alone

14. Together
vs.
Separately
• There is no significant difference identifying
[F(1, 11) = .012, p = .914]
and enumerating
[F(1, 11) = .527, p = .483]
when done together as compared to when
they are done separately

15. Summary
• Observers perform equally well when
enumerating and identifying target objects of
up to 4 objects.
• Identification performance remains constant
for the quantities 2-5, while enumeration
performance decreases significantly from 4-5.
• There is no difference in performance when
enumerating and identifying target objects
are done together or separately.

16. Conclusions
• These results suggest that a Visual Index
allows an observer to identify and
enumerate without significant error 2-4
target objects.
• The performance for enumeration and
identification diverge at the quantity 4-5,
with identification performance
significantly exceeding enumeration
performance.

17. References
• Pylyshyn, Z. W. (1989). The role of location indexes in
spatial perception: A sketch of the FINST spatial-
index model. Cognition, 32, 65-97.
• Pylyshyn, Z. W. & Storm, R. W. (1988). Tracking
multiple independent targets: evidence for a parallel
tracking mechanism. Spatial Vision, 3(3), 1-19.
• Trick, L. M. & Pylyshyn, Z. W. (1994). Why are small
and large numbers enumerated differently? A limited-
capacity preattentive stage in vision.