The document summarizes Anne Treisman and Garry Gelade's feature-integration theory of attention from their 1980 paper. The theory posits that features are registered automatically and in parallel across the visual field, while objects are identified separately and require focused attention to integrate the features. A series of experiments on visual search, illusory conjunctions, and texture segregation provide evidence that attending to conjunctions of features (e.g. color and shape) involves serial self-terminating search, while attending to individual features can be performed in parallel. The experiments demonstrate that precise spatial localization of objects requires attention to bind features with locations.

1. A Feature-Integration
Theory of Attntion
Anne Treisman & Garry Gelade (1980)
Jing Chen

2. Outline
• The Feature-Integration Theory of Attention
• Paradigms/Experiments
• Visual search (Exps 1, 2, &3)
• Illusory conjunctions (Exp 4)
• Texture segregation (Exp 5, 6, & 7)
• Identity and location (Exp 8 & 9)
• Conclusion

3. The Feature-Integration
Theory of Attention
• Features are registered early, automatically, and in
parallel across the visual field, while objects are
identified separately and only at a later stage, which
requires focused attention to “glue” features
together.
• Attention is necessary for the correct perception of
conjunctions, although unattended features are also
conjoined prior to conscious perception.
• “Illusory conjunctions”

4. Dimension vs. Feature
• “Dimension” refers to the complete range of
variation
• “Feature” refers to a particular value on a dimension
• Thus color and orientation are dimensions; red and
vertical are features on those dimensions.

5. Experiment 1: Visual Search
• Purpose:
• To compare search for disjunction targets and
conjunction targets;
• To explore the effect of extended practice on serial and
parallel search;
• Among the distractors Tbrown and Xgreen
• Disjunction targets: a blue letter or an S;
• Conjunction targets: Tgreen;
• Setsize: 1, 5, 15, and 30

6. Disjunction Target
Find the blue letter
• Easy: • Just as Easy:
X T X T T T X T
X T X T
X T X X T X T T
X T T X
T X T T X X T X
T X X X
X X T X T X T X
T T X T
T X T T X T X T

7. Conjunction Target
Find the green “T”
• Hard: • Even Harder:
X T X T X T X T T T X T
X T T X X T X X T X T T
T X X X T X X T X T T X
X X T X T X T X
T T X T
T X T T X T X T

8. Experiment 1: Results
• Conjunction: search time increased linearly
with setsize; search is serial and self-
terminating;
• Disjunction: for positive displays, search times
were hardly affected by setsize; for negative
displays, the relationship is linear;

9. Experiment 1: Results
• The effect of extended practice:
• There is little indication of any
change in the pattern of results;
• no sign of a switch from serial to
parallel search.

10. Experiment 1: Discussion
• Focal attention, scanning successive locations
serially, is the means by which the correct
integration of features is ensured.
• When this integration is not required by the task,
parallel detection of features should be possible.

11. Experiment 2: Visual Search
• Purpose: to explore the relation between the
discriminability of the features of a conjunction and
the speed (slop) of detecting that conjunction as a
target.
• Compare
• Difficult condition: a conjunction target in distractors
similar to it (T in X and T);
• Easy condition: distractors differed maximally from the
target (O in O and N).

12. Experiment 2: Results
• The slopes in the difficult
discrimination are nearly three times
larger than those in the easy
discrimination
• but the linearity and the 1/2 slope
ratio is preserved across these
large differences.

13. Experiment 2: Discussion
• The search rates vary dramatically for easy and
difficult conditions.
• In both easy and difficult conditions for the
conjunction targets, the search were serial, self-
terminating.
• As a result, we cannot say that search becaomes
serial only when it is difficult.

14. Experiment 3: Visual Search
• Purpose: to explore an alternative explanation for
the difference between conjunction and disjunction
targets.
• attributes the difficulty of the conjunction condition to
the centrality of the target in the set of distracters.
• Replicate this aspect of the similarity by using
unidimensional stimuli, with no need for checking
conjunctions.

15. Experiment 3: Results
• The pattern of results is quite
“Central”
different from that obtained
with the color-shape
conjunctions and disjunctive
features.
• When the intermediate target
is present, its detection
doesn’t depend on a serial
check of the distractor, which
the detection of the
conjunction did.

16. Experiment 4: Letter Search
• Purpose: to discover whether integrative attention is
required even with highly familiar stimuli, e.g., letters
• Confusability of letters
• Letters would be difficult to search when they are
similar in a wholistic way.
• R/PB
• Sets of letters would be confusable if their features
were interchangeable and could potentially lead to
illusory conjunctions.
• R/PQ

17. Experiment 4: Letter Search
• Purpose: to discover whether integrative attention is
required even with highly familiar stimuli, e.g., letters
• The conjunction condition (with interchangeable
features): R/PQ and T/IZ
• The similarity condition (with greater target/distractor
similarity): R/PB and T/IY

18. Experiment 4: Results
• The ratio of positive to negative
slopes differed for the
conjunction and the similarity
conditions:
• For the conjunctions, it was
0.45, which is close to half
and suggests a serial self-
terminating search.
• For the similarity condition,
it was much lower (0.26).

19. Experiment 4: Discussion
• Letter search would be serial and self-terminating if
the particular sets of distractor and target letters
were composed of perceptually separable features
which could be wrongly recombined to yield
conjunction errors.
• Otherwise search could be parallel (although not
necessarily with unlimited capacity and no
interference).

20. Experiment 5: Texture
Segregation
• Purpose: to investigates the “preattentive”
segregation of groups and textures, which could
guide the subsequent direction of attention.
• Five rows * five columns; card sorting task:
• The color condition: OV|OV
• The shape condition: OO|VV
• The conjunction condition: OV|OV
OOVOO
VOVVV
VOVOV The task was to sort the packs of cards into two
OOVVO piles, one containing cards with a horizontal and one
OVVOV with a vertical boundary.

21. Experiment 5: Results
• The difference between the two feature packs and
the conjunction pack was qualitative and obvious.
Face-up Face-down
• The color condition: OV|OV 15.9 25.1
• The shape condition: OO|VV 16.2 25.6
• The conjunction condition: OV|OV 24.4 35.2
•
• Suggesting that the boundary cannot be directly
perceived in the conjunction condition and has to be
inferred from attentive scanning.

22. Experiment 6: Texture
Segregation
• Purpose: to discover whether the advantage of the
feature boundary was due to
• In the feature pack, only one dimension was relevant
• But the conjunction pack, require attention to both
dimensions.
• Change the feature display into multiple-dimensional
one: OΠ|OV (26.9 vs. 32.9 sec)
• Results:
• The disjunctive features appear slightly less effective than
single features.
• The relevance of two dimensions rather than a single
dimension can explain only a small fraction of the difference
between features and conjunctions.

23. Experiment 7: Texture
Segregation
• Purpose: to see whether the distinction between features
and conjunctions is equally crucial when the features are
local components of more complex shapes rather than
values on different dimensions (as in 5&6).
• The single feature conditions (short diagonal line):
• PO/RQ (779 ms)
• EO/FQ (799 ms)
Again, what matters is
• The conjunction conditions: whether the boundary is
• PQ/RO (978 ms) defined by a single feature or
• FK/EX (1114 ms) a conjunction of feature

24. Experiments 8&9: Spatial
Location
• Purpose: to test whether precise information about
spatial location is available at the feature level,
• by looking at the dependency between reports of
identity and reports of location on each trial.
• Difference between Exps 8 & 9:
• In Exp 8, the presentation times of the arrays were
chosen to make sure the accuracy in each condition
was 80%.
• In Exp 9, equal presentation times were used for
features and conjunctions.

25. Experiments 8&9: Spatial
Location
• All distractors were OX
• The targets:
• The disjunctive feature condition: H, H, X, or O
• The conjunction condition: X or O
OXOXOO
• Dependent variable: OXOXHX
• accuracy with brief exposures

26. Experiments 8&9: Results
The conditional probabilities follow a very similar pattern.
It seems likely that in order to focus attention on an item, we must spatially
localize it and direct attention to its location.
Feature localization is a special kind of conjunction task (feature and spatial
location).

27. Conclusions
• All the data taken together support the feature-
integration theory of attention.
• Separable features can be detected and identified in
a early, parallel process;
• this process mediates texture segregation;
• locating any individual feature requires an additional
operation;
• conjunctions of features require focal attention to be
directed serially.