3. A spotlight on
attention
Attention is the process by which certain
information is selected for further
processing and other information
discarded. Attention is needed to avoid
sensory overload. The brain does not
have the capacity to fully process all the
information it receives. Nor it would be
efficient for it to do.
Metaphor of the bottleneck (e.g.
Broadbent 1958)
5. Visual attention
In terms of visual attention one
of the most pervasive metaphors is
to think about attention in terms of
a spotlight. The spotlight may
highlight a particular location in
space, it may move from one
location to another and it may even
zoom in or out.
6. Entrance from
stage right
Actors and the hidden
entrance from stage right
The right hemisphere is more
specialized for spatial processing
and it represent the left space
and, to a lesser extent, the right
one.
Right hemisphere lesions have
severe consequences for spatial
attention (neglect)
Source: https://youtu.be/Ys8-a0yD-MM
9. But Did You
See the
Gorilla?
Inattentional
Blindness
“How could they miss something right
before their eyes? This form of
invisibility depends not on the limits of
the eye, but on the limits of the mind.
We consciously see only a small subset
of our visual world, and when our
attention is focused on one thing, we
fail to notice other, unexpected things
around us, including those we might
want to see.”
https://www.smithsonianmag.com/science-nature/but-did-
you-see-the-gorilla-the-problem-with-inattentional-blindnes
s-17339778/#PBmjB0cD5yuFzX3v.99
10. Orienting the spotlight
We can assume that the spotlight initially shifts to the cued location, but if the
target does not appear attention shifts to another location (disengagement).
There is a processing cost in terms of reaction time associated with going back to
the previously attended location, called inhibition of return.
Exogenous orienting: attention that is externally guided by a stimulus
Endogenous orienting: attention is guided by the goals of the perceiver.
Visual search: a task of detecting the presence or absence of a specified target
object in an array of other distracting objects.
11. The pop out
phenomenon
In a visual search experiment, a target is the
item that you need to find. A distracter or
distractor is an item that you are not looking
for, and which distracts you from finding the
target.
● Searching for keys on a messy table
● Searching for your wallet
● Searching for tea-bags in the
supermarket
● Searching for your name on a list of
names
Source: https://www.psytoolkit.org/lessons/visualsearch.html
12. Cross-modal
integration: is space
the last frontier?
Spatial frames of reference may be
used to integrate information from
different sensory modalities such as
hearing, touch and vision.
Sinestesia Vs the ventriloquist effect
(i.e. the tendency to mis-localize
heard sounds onto a seen source of
potential sounds.
Source: https://www.youtube.com/watch?v=jtsfidRq2tw
13. Losing space: Seeing one
object at a time
Balint’s syndrome is a severe difficulty in
spatial processing normally following bilateral
lesions of the parietal lobe; symptoms include
simultagnosia, optic ataxia and optic apraxia.
Simultagnosia is the inability to perceive
more than one object at a time.
3 clinical characteristics of
Balint’s syndrome:
1) Inability to perceive more
than one object at a time
(simultagnosia)
2) Inability to reach in the
proper direction for an
object under visual
guidance (optic ataxia)
3) Fixation of gaze without a
primary deficit of eye
movement (optic apraxia)
14. Losing half of space: Spatial
frames and neglect
Is neglect a problem in low level perception or attention?
Functional imaging reveals that the objects in the neglected visual feed still
activate visual regions in the occipital cortex. So neglect is not a disorder of low
level visual perception.
One additional symptom of neglect that illustrate this point is called “extinction”:
when presented with two stimuli at the same time (one in each hemispace), then
the stimulus on the opposite side of the lesion is not consciously perceived.
16. Perceptual Vs
Representational
Neglect
Bisiach and Luzzatti (1978)
established that neglect can occur
for spatial mental images and not
just for spatial representation
derived directly from perception.
Exercise
Describe a place with the mind of
eye
Reference frames is a
representational system for coding
space
