1. Attention I failures to select information

2. What is attention? How is the word used? Examples:
something bright caught my attention
I didn’t see you, I was paying attention to the game
I struggled to pay attention to the lecture
I don’t remember even cleaning the table, I must not have been paying attention
Attention refers to many different kinds of mechanisms
Although we have an intuitive understanding of what it means to “pay attention” to an object or event, the study of attention has a long and checkered history in cognitive psychology, filled with debate and disagreement. Some have suggested that “everyone knows what attention is;” others have countered that “no one knows what attention is.” (p. 103)

3. Attention
Attention enhances some information and inhibits other information. The enhancement enables us to select some information for further processing The inhibition enables us to set some information aside.

4. Attention and limits on information
We need attention to limit the amount of information that is processed
Why are there limits on the amount of information we can process?
limited sensory systems

5. Example 2: Fovea demo
When perceiving a scene, can only get “pieces” of it at any instant; need to move eyes around to see scene
Need to move eyes around to see the world seye movements make jumps called saccades

6. Example 2: Fovea demo
When perceiving a scene, can only get “pieces” of it at any instant; need to move eyes around to see scene
Need to move eyes around to see the world seye movements make jumps called saccades

7. Eye tracking
Eye-tracking studies can tell us which information is attended to
Our eyes are drawn both by top-down information (e.g. a goal to find specific information) as well as bottom-up information (e.g. a flashing light)
Commercial intro on eye-tracking
Fixations: ~ ms; information is acquired
Saccades: extremely rapid movements between fixations
Eyemovement analysis of websites can show what a user is paying attention to, and what information the user might be missing.
Eye tracking device
eye movements during reading

8. Eye tracking and Visual Attention
slide from Marc Pomplun:
Subjects viewed ambiguous pictures that allowed two different interpretations A and B.
They were asked to press and hold a particular button while perceiving interpretation A, and a different button for interpretation B.
Afterwards, the fixations recorded during the perception of interpretations A and B were separated and separately visualized in the original image.

9. Eye tracking and Visual Attention
slide from Marc Pomplun:
Painting by Giuseppe Arcimboldo. Earth. c Oil on wood. Private collection, Vienna, Austria.

10. [From wikipedia] http://en.wikipedia.org/wiki/Eye_tracking
This study by Yarbus (1967) is often referred to as evidence on how the task given to a person influences his or her eye movements.
[Yarbus 1967]

11. Improving layout with eye-tracking studies

12. David Hockney’s photo collage might be a metaphor for the way we see scenes
wolfe-fig jpg
1 photo = 1 gaze

13. Attention and limits on information
Human information processing is massively parallel, up to a point where we have serial bottlenecks
Bottleneck: a restriction on the amount of information that can be processed at once forcing serial processing
Serial bottlenecks:
limited sensory systems
limited effector systems
movements must be planned sequentially
words can only be spoken sequentially

14. Inattentional Blindness
After bottleneck, it is the allocation of our attention that determines what is analyzed.
Often, we are unable to process information that is unattended. This can lead to inattentional blindness (related to change blindness)
From Simons & Chabris (1999) paper:
“we often do not detect large changes to objects and scenes (`change blindness'). Furthermore, without attention, we may not even perceive objects (`inattentional blindness').”

15. Do you notice the change?
From O’Regan (1999) paper:
“Change-blindness occurs when large
changes are missed under natural viewing
conditions because they occur simultaneously
with a brief visual disruption, perhaps
caused by an eye movement, a flicker, a
blink, or a camera cut in a film sequence.”
“Central-interest changes were usually
detected as soon as they occurred, whereas
marginal-interest changes were seen only on
their second or later occurrences. In 13–30%
of the cases, marginal-interest changes,
although in full view, were not detected at all
during the 40-s viewing period.”
“Part of the explanation for these effects
is that attention-grabbing luminance transitions,
caused all over the visual field by the
brief visual disruptions, prevent attention
being focused on the location of the change.”
“it seems that change-blindness occurs because
the internal representation of the visual
world is rather sparse and essentially contains
only central-interest information.”
Some of these demos are from: Simons & Levin, 1997, TINS, 1,

16. Do you notice the change?
Some of these demos are from: Simons & Levin, 1997, TINS, 1,

17. Do you notice the change?
Some of these demos are from: Simons & Levin, 1997, TINS, 1,

18. Do you notice the change?
Some of these demos are from: Simons & Levin, 1997, TINS, 1,

19. Other demos Lots of demos:
Airplane demo
Dinner demo

20. Inattentional Blindness
Why is it hard to notice the change (initially)?
When motion detection is disrupted, it is very difficult to observe changes to unattended image locations
Brain makes reasonable assumption that things do not change unexpectedly (in the absence of motion cues).

21. Demo of basketball players
Task: count the number of times the white team passes the ball to each other
Important to pay close attention to the white team
Demos at:
From Simons & Chabris (1999):
“the likelihood of noticing an unexpected object depends on the similarity of that object to other objects in the display and
on how difficult the priming monitoring task is. Interestingly, spatial proximity of the critical
unattended object to attended locations does not appear to affect detection, suggesting that
observers attend to objects and events, not spatial positions.”
“Neisser and his colleagues used this `basketball-game' task [see Neisser (1979) for a description of several different versions].
In the most famous demonstration, observers attend to one team of players, pressing a
key whenever one of them makes a pass, while ignoring the actions of the other team.
After about 30 s, a woman carrying an open umbrella walks across the screen (this video
was also superimposed on the others so all three events were partially transparent; see
figure 1). She is visible for approximately 4 s before walking off the far end of the screen.
The games then continue for another 25 s before the tape is stopped. Of twenty-eight
naive observers, only six reported the presence of the umbrella woman, even when
questioned directly after the task (Neisser and Dube, cited in Neisser 1979). Interestingly,
when subjects had practice performing the task on two similar trials before the trial with
the unexpected umbrella woman, 48% noticed her. When subjects just watched the
screen and did not perform any task, they always noticed the umbrella woman, a result
consistent with the inattentional-blindness findings reviewed earlier (and with work
on saccade-contingent changes; see Grimes 1996; McConkie and Zola 1979).”
“Interestingly, Neisser (1979) mentioned an additional study in which the umbrella
woman wore the same-color shirt as either the attended or the unattended team.
Apparently, this feature-similarity manipulation caused little difference in the rate of
noticing. Also, when the unexpected character was a small boy rather than the umbrella
woman, fewer subjects noticed him, and when the umbrella woman stopped her motion
and performed a little dance, more subjects noticed. These latter two findings suggest
that properties of an unattended stimulus can capture attention, even though similarity
to attended stimuli seemed to make little difference. However, these findings must be
evaluated tentatively, because the details of the experimental paradigm were not presented
by Neisser (1979).”
“Out of all 192 observers across all conditions, 54% noticed the unexpected event and
46% failed to notice the unexpected event, revealing a substantial level of sustained
inattentional blindness for a dynamic event and confirming the basic results of Neisser
and colleagues.”
Did you notice anything unusual? no
yes
(Simons & Chabris, Perception, 1999, 28, 1059 – 1074)

22. (not) noticing person changes
Demos from Dan Simons (University of Illinois):
Another demo with gender change:
Failures of selection in space can be of surprising magnitude. Perhaps the most dramatic of these was a demonstration by Simons and Levin (1998) in which an experimenter stopped pedestrians on a college campus to ask for directions.
During each conversation, two people carrying a door walked between the experimenter and the pedestrian. As they did, the experi­menter switched places with a second experimenter who had been concealed behind the door as it was being carried. This second experimenter then continued the conver­sation with the pedestrian. Only half the pedestrians reported noticing the change of speaker—even when they were explicitly asked, “Did you notice that I am not the same person who first approached you to ask for directions?” (p. 105)
see also letter task:

23. Inattentional Blindness
Shows there are remarkable gaps in our perception
Human’s interpretation of the visual field is much sparser than the subjective experience of “seeing” suggests
Our visual system might be overwhelmed without change blindness -- in a real-world setting with many moving objects, it might make sense to “track” only a few objects
From O’Regan et al. (1999) paper:
“These results indicate that humans’
internal representation of the visual field is
much sparser than the subjective experience
of ‘seeing’ suggests. Only the parts of the
environment that observers attend to and
encode as interesting are available for making
comparisons.”
“If only attended parts of the environment
are represented in the brain, how can
we have the impression of such richness and
completeness in the visual world outside us?
The answer might be that the visual world
acts as an external memory. We have the
impression of simultaneously seeing everything,
because any portion of the visual
field that awakens our interest is immediately
available for scrutiny through an
unconscious flick of the eye or of attention.
However, those parts of the scene that are
not being currently processed (and are in
some sense not ‘seen’) nevertheless constitute
a background or setting that enlivens
our visual experience.
The idea of the world as an outside memory
is receiving attention from scientists and
philosophers interested in the problem of
perceptual ‘filling in’ of visual scotomas and
illusory contours. Work in robotics with the
concept of ‘active’ vision is also adopting the
notion that using the outside world to represent
information might be more efficient
than making an internal copy.”
From Simons & Chabris (1999):
“The richness of our visual experience leads us to believe that our visual representations will include and
preserve the same amount of detail”

24. Failures of Selection in Time
When new information (even if only a small amount) arrives in a rapid stream, spending time processing it will cause you to miss some other incoming information, resulting in what are called failures of selection in time.

25. Attentional Blink From Wikipedia:
“One curious aspect of attentional blink is that it usually includes "lag 1 sparing", meaning that targets presented very close together in time (at "lag 1" or consecutively in the RSVP stream) are not affected by the attentional blink, even though items presented at slightly greater lags are significantly impaired. There is as yet no conclusive explanation for the phenomenon of lag 1 sparing, although it is thought to be related to the first parallel stage of the two-stage system of stimulus selection and processing.”
“One mechanism that may give rise to the attentional blink is that both targets (T1 and T2) can be processed in parallel if presented close enough together; otherwise serial processing takes over, which creates a temporary bottleneck for subsequent processing of T2 from visual short-term memory. An alternative account posits that the bottleneck occurs in a limited-capacity processing stage required for awareness and preparation of a response. There are also hybrid models that incorporate both of these ideas.”
Demos:

26. Sources of Limitation
The attentional blink is a short period during which incoming information is not registered, similar in effect to the physical blanking out of visual information during the blink of an eye.
Divided-attention studies demonstrate that performance is hampered when you have to attend to two separate sources of visual information or two separate visual events. In all these cases, the decrement in performance is referred to as dual-task interference.
The interference, in the form of a slowing down of your actions, that arises when you try to select between two possible responses to even a sole sensory stimulus is referred to as a response bottleneck. The additional time needed to move through this kind of bottleneck has been measured experimentally. (p. 115)