retinal image is precisely what one would predict if perceived size is
governed not only by visual angle but also by distance. The two
seemingly different facts, that images of the same si
ze lead to
perceptions of different size (Emmert’s law), and that images of
different size lead to perceptions of the same size (size constancy),
actually illustrate the same principle: distance is taken into account in
computing the size of a perceived ob
ject from the size of the image
falling on to the retina, which is another example illustrating that we
don’t just see what our eye tells us.


Third experiment

When you close your left eye and adapt to the figure with your right
eye, only your right eye wi
ll see an after
-
image when looking at a white
region. The after
-
image does not transfer between eyes. This helps
scientists determine where in the visual system this effect arises. This
type of after
-
effect is caused by cells in the retina fatiguing, rath
er than
by cells in the visual cortex, where information from the two eyes is
combined.




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The active nature of perception


Factors that further explain perception and our perceptual world are embodied
in what are called ‘The principles of perceptual or
ganisation’ which include:




Gestalten; figure and ground



perceptual constancies; for example, depth perception


Gestalt psychology and Gestalten


One way of looking at perception is from the point of view of Gestalt
psychology (Kohler, Koffka and Wert
heimer); see p. 24. It is easily
understood. Gestalt psychology, which was in vogue in Germany in the early
part of the twentieth century, postulates that we have an innate disposition to
perceive objects using our inbuilt principles of
grouping
, or
Gesta
lten
. What
Gestalten means is our innate ability to construct our world in terms of
organised ‘wholes’. It is as if we have a natural ability to ‘tidy up’ stimuli as
we sense them. Their
Laws of Pragnänz

capture the principles behind our
Gestalten, which a
re our innate way of perceiving things in terms of
symmetry, uniformity and stability. Individual Gestalten are:


Proximity

Objects that are close together are perceived by us as a ‘whole’, e.g.


a)

.

.

.

.

.

.

b)

.......................


How do you perce
ive a) and b) above?


Similarity

Similar objects are normally perceived by us as belonging to the same group.









Above, what similar sets of objects do you perceive as a group and what other
one do you see


or think you see


which does not exist in

reality? Storm the
reality studios!


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Continuity

Sensations appearing to create a continuous form are perceived by us as
belonging together, e.g. a fence with slats missing is still perceived as a
fence. We organise sensations appearing together to form

a continuous whole,
e.g.


x x x

x x

x x

x x x


Do you perceive the above as a square shape made up of Xs, or ten separate
and individual Xs?


Closure

Where, at an unconscious level, we fill in contours/gaps in stimul
i to form a
complete whole in order to make perceptual sense of it, we need to bear in
mind the importance of past experience and perception. This is illustrated
below. What do you make of these stimuli? Your tutor should explain the
significance of this s
imple demonstration.














The whole is greater than the sum of its parts


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Texture


Texture is another principle of Gestalten where objects of the same texture
are perceived as belonging to the same group, e.g. grains of sand and pebbles
at the
seaside form for us a ‘beach’.


You are unlikely to perceive the scene above as made up of individual grains
of sand.


Simplicity

We have a tendency to group together stimulus features in a way that
provides the simplest interpretation of the world (e.g.
houses as opposed to
their make
-
up


windows, doors, roofs, walls, ceilings, etc.). The notion of
simplicity does have a link with the social psychological phenomenon of
stereotyping and attribution theory.


Common fate

This strange term describes the prin
ciple where individual objects moving
together at the same rate are perceived by us as a group. We group, by
common fate, flocks of seagulls and swarms of wasps. We do not perceive
each individual in the flock or swarm. We innately organise the stimuli int
o a
‘whole’ in order to perceive and understand it.


Innate principles behind Gestalten and Gestalt psychology, which are
biological in origin, go some way to explain perception. Perception is
therefore more than mere ‘seeing’. We often find in psychology

that such
innate abilities have survival value for us.

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Student Activity


Figure and ground


What do you make of the visual stimuli below?



This stimulus is known in psychology as
Rubin’s vase

and is often used
to demonstrate illusions. Danish psyc
hologist Edgar Rubin made the
vase/profile illusion famous in 1915. As you might be able to ‘see’ from
Rubin’s vase, our visual perceptual process puts some aspect of the 2
-
D
stimuli to the ‘front’ or foreground (
figure
) and another aspect to the
meaningle
ss background (
ground
). Some part of the image always
stands out as ‘figure’ and some other part ‘ground’. With Rubin’s vase
the principle is reversible. What is meant here is that you will either
perceive a vase to the front or two faces squaring up to ea
ch other!
Often what we perceive (as above either a vase or faces) is related to
our:




expectations



culture



experience of the stimuli



motivation



social world.


All of these influences on perception are collectively called our

perceptual set
’.



The work of the Dutch artist M C Escher is famous for its ability to
trick the eye.


Please answer the questions that follow.


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Perceptual set?




E

A

D

13

A




16

15

14

B

12




The cat sat on the map and licked its whiskers


1.

Look at three stimul
i above. Explain each from the point of view
of perceptual set.


2.

Below are what might appear as blobs when you first look at
them. Your impression of the blobs provides an example of
awareness at a sensory level. If you continue to look at the blobs,
f
our words will emerge. You needn’t try to organise the blobs.
The organisation process will occur without any overt striving on
your part. These blobs have been created to slow the perceptual
process so that you can experience what typically occurs speedil
y
in subjective time. After you have perceived what they are, use
the explanatory thumbnail to help you explain what you have just
done.



Your first and seemingly
immediate awareness, which
more or less corresponds to
the energy stimulation
patterns, is

referred to as
‘sensation’. ‘Perception’ can
be distinguished from
sensation in that it refers to a
process that requires more
organisation than sensation,
is more heavily dependent on
learning than sensation, and
requires more time for
completion than se
nsation.


Explain the difference
between a
sensation

and a
percept
.

Keep
off the the
grass

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3.

Below is the famous illusion in psychology attributed to Boring.
From the point of view of your perception, what do you first
perceive? Can you perceive anything else? Explain this
illusion in
the light of factors that influence perception.





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Development and perception


Do we have innate, or inborn, perceptual abilities, and as a result can we
discover whose is the more correct viewpoint as regards our perceptions: the
direc
t/ecological viewpoint or the indirect/constructivist viewpoint?


Bower (1966) is, amongst other things, famous for his peek
-
a
-
boo experiment
into our perception of size constancy, otherwise known as relative size. He
set out to discover if size constanc
y in babies was a consequence of
experience or was innate. He conditioned young babies (neonates) of two
months to turn their heads on the presentation of a 30
-
centimetre cube at a
distance of 1 metre away from them. They were then presented with three
fur
ther conditions of the independent variable:




a 30
-
centimetre cube at 3 metres



a 90
-
centimetre cube at 1 metre and



a 90
-
centimetre cube at 3 metres (which produces the same size of retinal
image as the 30
-
centimetre cube at 1 metre).


He recorded the

number of times each stimulus produced the conditioned
response (head turning) and his results showed:




Condition 1 (30 cms


1 metre):

98 head turns



Condition 2 (30 cms


3 metres):

58 head turns



Condition 3 (90 cms


1 metre):

54 head turns



Cond
ition 4 (90 cms


3 metres):

22 head turns


The finding that most head turns occurred in response to the first stimulus
showed that the babies were responding to the actual size of the cube
irrespective of distance. This supports the ecological and Gestalt

position of
size constancy being innate. Further research by Slater (1989) supports
Bower’s findings, and suggests that size constancy (our ability to perceive the
true size of an object) is actively and provably present in babies as young as
eighteen wee
ks.


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A further study by Bower investigated the innate Gestalt principle of closure.
He conditioned neonates to respond to triangle number 1 and then presented
them with 2, 3, 4 and 5.










Number 1

Number 2

Number 3









Number 4

Number 5


Bower f
ound that the conditioned response was generalised more by the
babies to the complete triangle (number 2). It is suggested that with number 1
the young babies initially perceived an unbroken triangle to lie behind the
black bar and that this indicates that

the Gestalt principle of closure is innate
in all of us. These innate Gestalt

principles are the basis for further and more
complex perceptual organisation.


R L

Gregory is a cognitive psychologist who takes a constructivist approach
to perception. He say
s that we often (have to) go beyond the evidence of
sensory information alone to understand and behave appropriately in our
world. He believes experience in our environment has a part to play here. He
used visual illusions in an attempt to prove his point.

Visual illusions see us
interpreting them as
more than just
sensory input alone. This was
demonstrated earlier. With the old woman/young woman illusion did you
first/always see a young or an old woman? Which is the more correct
interpretation of the stimu
li? We often use knowledge of visual illusions to
our advantage. DIY programmes are about altering perceptions to make
rooms more appealing. If you have a small bathroom or kitchen and want to
create an illusion of size, DIY programme presenters often use
the Muller
-
Lyer illusion and paint horizontal lines on alternate rows of tiles giving

an impression of depth, or use vertical lines to create height


where none

in reality exists. By using the natural contours of the room, like corners,

they work on ou
r environmental experiences of cues to depth, i.e. two

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railway lines that appear to converge into the distance are used as an external
clue to depth in our world. This is illustrated at (b) below.



(a)

(b)










On the other hand there are psycho
logists such as Gibson and Walk (1960)
who believe

more in an ecological or bottom
-
up approach in their
understanding of our perceptual processes


at least as far as depth perception
is concerned. As can be seen on page 51, in their famous visual cliff
ex
periment, they discovered in their work with kittens and neonates that
depth perception is probably innate in humans as it is in kittens. This
suggests that the application of our
innate
perceptual abilities are important
from the point of view of personal

survival. They have come about as a result
of evolution. It would appear in the application of perception that we benefit
from both theoretical positions. Some abilities that influence perception
appear innate


but experience of our environment and what
we learn in it is
important as well.


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Perception study


Source:

Gibson, E J and Walk, R D, ‘The visual cliff’,
Scientific American
, 202, pp.
64

71, 1960


Aim:

To discover if depth perception is innate or learnt.



Participants/subjects:

Children aged 6

1
4 months


Animals aged 24 hours


Method:

Laboratory experiment


Independent variable: age of participants


Dependent variable: whether baby crawled to deep side of visual cliff.


Procedure:

Visual cliff constructed of glass over a box with black and white

squares
positioned to show depth at one end.


Infants were placed in the middle and encouraged to move towards their
mothers who waited at the opposite end.

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Animals, e.g. rats, chickens, turtles and lambs were also tested by placing
them in the middle a
nd observing to which end they went.


The reason why Gibson and Walk used both animals and humans in their
study is that babies could not take part until they can crawl (around 6 months)
by which time the learning of depth perception may have occurred. Non
-
human animals were used at an earlier age (as young as one day) where it was
fairly certain no learning of depth perception could have occurred.


Conclusion:

Gibson and Walk (1960) suggest non
-
human animals are born with innate
ability to perceive depth a
nd that babies as young as 6 months could perceive
depth, though there is no indication if this is innate or learned. Neither the
direct ecological view nor the indirect constructivist view is entirely
supported.


Perceptual constancy


So far we have esta
blished that perception depends upon bodily structures
and processes; our innate principles of Gestalten, and us imposing 3
-
dimensional meaning on 2
-
dimensional visual experience on the basis of
expectations, culture, experience, motivation and our social
world


sometimes wrongly! Perception is actively influenced by all these factors
working individually and together. Where this all ultimately happens is
within the human brain, centring on the hypothalamus in particular.


We also have a perceptual abilit
y, collectively called perceptual constancies,
which helps us to perceive our world. Where our perceptual constancies of
size, shape, brightness and depth come from is not fully understood.
Cognitive psychologists disagree as to whether they come about as
a
consequence of our biology and genetic inheritance (nature) or as the result
of learning and experience (nurture). It should be said, however, that as far as
depth constancy is concerned, there is good psychological evidence to
suggest that depth percept
ion is innate.


Perceptual constancy is our ability to perceive sameness of visual stimuli
even when the sensory evidence is to the contrary. We have a perceptual
constancy in the four areas below that also help us make sense of our
perceptual world.




s
ize



shape

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brightness



depth


Perceptual constancies occur when our brains correct or modify our rapidly
changing sensory inputs to give us a more constant perception of the world.
For example, size constancy ensures that as we watch a friend walk off

into
the distance, although the image of the person projected on to our retina is
rapidly decreasing in size, we do not perceive that our friend is actually
shrinking! The knowledge that as the proximal stimulus (the internal sensory
image) changes, the d
istal stimulus (the external object being perceived) does
not, allows us to correct our sensations and maintain constant perceptions.


Cognitive psychology has over the years offered three theories about
perception. It is in the area of perceptual constanc
ies that much supporting
evidence to which theory is the more correct has emerged.


These theories are summarised as follows.


Three theories of perception: direct, constructivist, and interactionist


1.

Bottom
-
up (ecological view): (Gibson; Gestalt



organised wholes’)
where it is said we perceive most clues from our environment
directly

and without interpretation (we perceive ‘exactly’ what we
see/hear/smell/touch and taste). The ecological or direct view explains
perception as being ‘bottom
-
up’


our

world impinges on our senses
which process the information to the brain where it is directly
interpreted, understood and acted upon. Bottom
-
up theory cannot
explain illusions.



Discussion point


Why do you think the bottom
-
up theory of perception cannot

explain
illusions? Why can’t bottom
-
up theory be dismissed altogether? Give
reasons for your deliberations.


2.

Top
-
down (constructivist view): (Gregory; Bruner) who say our
perceptual system must often make a reality indirectly out of bits of
sensory inf
ormation due to the absence of other information. They are
top
-
down in their explanation of perception. Higher
-
level cognitive
functions play a part. We often perceive things in the absence of bits of
sensory information by hypothesis testing or ‘best gues
sing’ on the
basis of our previous (in)experience of what it is we sense.


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Discussion point


What is the key to a top
-
down theory of perception? What other
influences would operate on a top
-
down perceptual understanding of
our world?


3.

Top
-
down/botto
m
-
up (interactionist/symbiotic view): (Neisser; Marr)
who say we use both top
-
down and bottom
-
up information processes in
the perception of our reality. Nature and nurture both play a part. Both
enhance perception individually and collectively. When one pe
rceptual
process, or aspect of it, is impaired, the other process, or an aspect of it,
‘fills in’ or compensates to give us at the end of the day as good an
individual understanding of the image/object/event as possible.
Symbiotic processing is best explai
ned in the area of visual perception
using Marr’s computer analogy where he says we extract visual
information from an image/object/event in four stages and put all this
together again in the brain in what he calls a symbolic representation of
the stimulus
. Marr’s computational model as an explanation of visual
perception is illuminating in that it helps emphasise the role of both
bottom
-
up and top
-
down processing independently, collectively and
integratively.



For an overview of Marr’s computer analogy s
ee overleaf.



Interactive


Read Theories of Visual Perception: Problems and Perspectives at
http://www.psychol.ucl.ac.uk/alan.johnston/Theories.html

and

Two
Visual Systems and Two Theories of Perception: An Attempt to
Reconcile the Constructivist and Ec
ological Approaches

by Joel
Norman of the University of Haifa, Israel at
http://psy.haifa.ac.il/~maga/tvs&ttp.pdf


For next day read Chapter 2 of
Cognitive Psychology

by Richard Gross
and Rob McIlveen (Hodder & Stoughton). Summarise each of the three
theor
ies/approaches to our understanding of perception. In your
opinion, which appears the most correct? Give reasons for your
answers.


It is to be hoped that good students will refer to psychological and
everyday examples in their deliberations.


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An intera
ctionist view


David Marr (1945

80) was a British psychologist who made important
contributions to the study of visual processing. In doing so, he integrated
results from psychology, AI, and neurophysiology. His classic book,
Vision:
A computational invest
igation

into the human representation and processing
of visual information
, is considered one of the most important works in
cognitive science. In addition to his work on vision, Marr developed a general
account of information
-
processing systems in terms o
f three levels of
analysis: (1) the level of computational theory of the system, (2) the level of
algorithm and representation, which are used to make computations, and (3)
the level of implementation: the underlying hardware or ‘machinery’ on
which the co
mputations are carried out.


Algorithm

An algorithm is a mechanical and completely reliable procedure or set of
instructions for completing an operation in a finite number of steps. For
example, ‘To unlock a door with an unfamiliar set of keys, try each
one until
one of them does unlock the door’. Another example, from logic, is truth
-
tables, which determine whether a formula is a tautology. In mathematical
contexts, an algorithm is a mechanical procedure for computing a result or
outcome. Use of an algor
ithm always provides a solution to a problem, unlike
a heuristic.


In an attempt to understand the complex make
-
up of our visual perception
David Marr


in ‘Marr, D (1980), Visual information processing: the
structure and creation of visual representation
s.
Phil.Trans.R.Soc.Lond
.B,
290, 199

218’


argues that neural activity transforms sensory (essentially
visual) stimulation into our experience of reality. This is done gradually, by
our extracting and deconstructing specific information from the object we

‘see’, in four stages and then putting all this information together again in our
attempt to recognise and understand what is we are (visually) perceiving.
Marr calls this a symbolic representation.


Representation

‘Representation’ can refer to a symbol o
r thing, which represents

(‘refers to’, ‘stands for’) something else, or it can refer to the relation
between a representation (in the sense just described) and what it

represents. In either case, there are many kinds of representation. For
instance, the
re are linguistic forms of representation (as exemplified

by the words in this sentence) and non
-
linguistic forms of representation

(as exemplified by maps and models). General questions about

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representation focus on the nature of the relation between a

representation
and what it represents, features which distinguish representations from other,
non
-
representational items and features which distinguish different kinds of
representation. Questions about representations, which arise in connection
with ment
al states and cognition, involve the representational nature of
imagery (is it more picture
-
like or language
-
like?), the creative use of
representational systems, and the relationship between language and thought.
These questions are of particular concern
for computational models of mind,
which require that mental representation be in a form suitable for
computation.


Marr’s (1982) 4 module computational theory of vision


1.

The image or grey
-
level description



Represented by the intensity of light at eac
h point in the retinal image,
this allows us to discover the boundaries of and regions in the image.
Marr suggests our ability to identify boundaries and regions on this
basis is the beginning of visual perception.


2.

Primal sketch



Here Marr says we go
on to identify surface markings, object
boundaries and markings using the Gestalt principles of grouping.


3.


-
D sketch



A third stage where in the deconstruction of an image we give it depth
and orientation. It is not yet 3
-
D. Object recognition needs

the input
matched against memory so that non
-
visible points are accounted for
(perceptual constancy).


4.

3
-
D model representation



Where the nature and construction of the object is at this final stage
confirmed/denied using higher level top
-
down proces
sing functions and
abilities. This gives rise to a symbolic representation of our visual
reality and is for Marr true object recognition.


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Our three theories of perception and their explanations of constancies


Size constancy

As previously explained, size

constancy refers to the fact that, although
retinal images of objects get smaller as the object recedes into the distance,
we perceive that the object does not change in size. Taking size constancy
into account, the constructivist view of perception maint
ains that size
constancy develops because we learn through experience that objects do not
actually shrink as they move away from us. Some cross
-
cultural evidence is
consistent with this view, in that sometimes people from the dense jungle or
heavily wooded

regions, who are not accustomed to viewing objects at a
distance, mistakenly perceive distant objects as being very small. Ecological
direct
-
perception theory on the other hand maintains that size constancy
occurs as a direct result of the information tak
en in by our senses and that
failure to conserve size results only when the situation does not provide us
with enough direct sensory information.


Shape constancy

Shape constancy is our ability, innate or learned, to perceive the shape of an
object as bein
g constant even though our retinal image of the object is
changing. An example of this would be the chalkboard at the front of your
class. Regardless of where we are sitting, we all perceive the chalkboard as a
rectangular shape despite the fact that we al
l have different retinal images of
it depending upon where we are sitting. Constructivists, or top
-
down
theorists, see shape constancy coming about as a product of learning in our
environment whereas bottom
-
up theorists see shape constancy as being
somehow

innate and part of the experience of sensation.


Brightness constancy

Lightness, or brightness constancy, refers to our perceptual ability to adapt to
the situation where the illumination (brightness) of an object changes, but we
continue to perceive its

brightness and colour as the same or constant. A
white sheet of paper first perceived in bright sunlight will still appear white
and of approximately the same shade when later perceived by us under the
shade of a tree. Constructivists (top
-
down theory) ex
plain brightness
constancy in our learnt knowledge that objects do not change their
‘brightness’ as lighting conditions change. Ecological theory takes a bottom
-
up explanation of brightness constancy. They say that enough information is
present in the sens
ory experience itself to allow us to maintain a constant
(lightness) perception of the object.

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Which is the more correct is very difficult to ascertain. Because babies cannot
communicate very well when first born, we have little way of knowing if
these c
onstancies are present from birth, or learnt (however quickly), as the
result of experience. We may find a more accurate explanation to the origins
of perceptual constancies in an examination of depth perception.



Student Activity


Depth perception


An a
wareness of depth perception will help us understand why it is we
visually sense the world in two dimensions (like a photograph) but
perceive what we see in three dimensions!


This is demonstrated below:












Above (left) is a Swedish stamp based
on the original diagram on the
right by the British physicist Roger Penrose (1954) called an Impossible
Triangle. They are each obviously two
-
dimensional. Are you currently
experiencing both in three dimensions? Shut one eye. Do you still
experience both i
n 3D? If you are this definitely contradicts direct
perception bottom
-
up theory as an explanation of perception.


Now the hard bit: why is this the case?


Without depth perception we would find walking, reaching, driving and
playing games (among other thin
gs) difficult. We see depth in our visual
world because of




monocular depth cues, and



binocular depth cues.


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Monocular depth cues


Monocular depth cues come about from seeing the world with one eye; or our
two individual eyes singularly...think about

it!! Monocular depth cues, or
cues to depth, come to us from our external world. Put simply, what things
are and where things are in our external world gives us cues or clues to depth.


Even if we visually experience our world with one eye, and the image

which
is striking our retina is definitely two
-
dimensional, where things are in our
visual field allows us understand or perceive our world in three dimensions.
Monocular depth cues include, inter alia, interposition, linear perspective and
relative size.


Interposition/superposition

One monocular depth cue we call interposition or overlapping. Interposition
is the monocular cue we use to perceive depth when we see a scene in which
one object is partially obscuring another. The object we can fully see we
p
erceive as nearer than the partially obscured object


which we perceive as
behind. If your tutor sits down behind their desk we can adjudge that the desk
is nearer you than they are: you can fully see the desk and only the top half of
their body. The inte
rposition of the desk and the tutor is here a monocular
depth cue.
















A

B

C


Interactive


Explain interposition, with reference to the above three figures.


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Shades and shadows


When we know the location of a light source and see objects

casting shadows
on other objects, we learn that the object shadowing the other is closer to the
light source. As most illumination comes downward, we tend to resolve
ambiguities using this information. Shadows in 2
-
D images are used by the
advertising ind
ustry and sign writers to attract our attention to the ‘fact’ that
the words seem to stand out from their background, giving the impression
that the background is farther away from the letters. Why? We notice it more!











Another monocular depth cu
e is:


Linear perspective

Linear perspective is another monocular depth cue. If we see two parallel
lines converge into one another in the distance, this tells us about depth. It is
easily demonstrated in a railway station. When it is safe (!) look down at

the
railway lines. They are parallel to one another. Now look up the track and
you will see the rails converge (come in on one another). This is linear
perspective. If we see this happening, it is a monocular cue to depth or
distance. Linear perspective c
an even work in two dimensions, i.e.














Which of the two horizontal lines above is longer, the one at the top, or the
one at the bottom? Measure them. What do you find? From the point of view
of perceptual theory why did you perceive what you di
d?

G
G


K
K
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Relative size



Relative size is another monocular depth cue. Relative size occurs when we
see two objects, like two houses, against their backgrounds in our visual
field. We see in two dimensions that one house is smaller than the other.
Indeed the
2
-
D visual information we receive about the smaller of the two
houses would appear to suggest it is the size of a match
-
box! This is not the
case. We perceive on the basis of relative size that the visually smaller house
is farther away from us. The larger

of the two we perceive as nearer.


The human visual system interprets depth in sensed images using both
physiological and psychological cues. Some physiological cues require both
eyes to be open (binocular); others are available also when looking at image
s
with only one open eye (monocular). All psychological cues are monocular.
In the real world the human visual system automatically uses all available
depth cues to determine distances between objects.


Binocular depth cues


Binocular physiological depth
cues are easy to understand. They come about
because we have two eyes. Binocular cues to depth in our visual field result
because of the fact that each of our eyes receives a slightly different picture
of the same scene; our noses see to that.

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The dual a
nd overlapping picture we get as a result is called
stereopsis
.
Stereopsis gives us binocular cues to depth because most of us enjoy
binocular (two
-
eye) vision. We can lose the ability for binocular depth cues
to our visual world due to a blow to the head
(that gives us double vision) or
damage to the eye due to strabismus (squints), etc. Sports people generally
have excellent binocular vision. You will find that professional sports people
whose game involves a ball of some description are usually excellent

at other
ball sports they play as a ‘hobby’. Stephen Hendry, the world
-
famous snooker
player, is an excellent golfer. The goalkeeper Andy Goram has Scottish caps
for both football and cricket. Ian Botham played both professional cricket and
professional f
ootball


though not at the same time of year.


If we have two eyes, when objects get closer to us, each eye turns inwards.
As objects, or
percepts
, move farther away, each eye turns outwards. The
brain interprets this as a binocular cue to how near or ho
w far the percept
(image/object) is from us. This inward and outward movement of our eyes in
response to how near or how far a percept is from us is called
binocular
convergence
.


Because each eye has a slightly different view of the same visual world, thi
s
similar, but different information is also used to help us judge depth. The
closer each retinal image (or picture) is to the other, the nearer our brain
interprets an object being to us. This is called
binocular disparity
.


We therefore achieve depth pe
rception due to monocular and binocular depth
cues. Monocular depth cues come from our visual environment. Binocular
depth cues arise because we have two eyes. The biology of the human body
gives rise to binocular depth cues. Our external environment gives

us
monocular depth cues.





Student Activity


Describe and explain how we perceive depth in our world.


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Motivation


In psychology, motivation concerns what prompts us to action or to behave in
a particular way. Motivation can affect our perception of o
bjects, events,
people stimuli, etc. Motivation in psychology is a study all in itself.
Cognitive psychology understands that our motivation to react, act and
behave in a particular way is affected by two things. These are our




internal biology; and



e
xternal environment.


Sometimes our internal biology and external environment come together to
make us think, feel and behave in a particular way. The interaction of our
biology and our environment as they motivate us to be more perceptually
aware produce
s interesting


and expensive


results.


When our body needs fuel, i.e. food, it tells us so when we experience hunger
pangs. This is our body’s internal signal or cue to us to eat. Our biology
affects our perception in that when we are hungry and experi
ence hunger
pangs, we perceive food much more vividly. It is fatal to go food shopping in
a modern supermarket if you are hungry. The fruit appears more appealing,
the home baking more delicious, the meat and fish more tasty looking! We
perceive the colou
r of food more intensely. We are more aware of the smell
of food. Perception of food is heightened by internal bodily factors. External
factors like the clever use of lighting to illuminate fruit colouring more, and
the bakery in the supermarket constantly

baking bread and cakes, also
influence and motivate us to perceive food more intensely when hungry. The
internal and external factors of motivation strongly influence our perception
of food and in this situation we may end up buying and spending much more

than we needed! Supermarkets of course are aware of this. A knowledge of
cognitive psychology can affect your waistline, wallet and purse.


Cultural variations on perception


In 1966 Mundy
-
Castle investigated the interpretation Ghanaian children

of betw
een 5 and 10 put on their line drawings. They were presented with

a series of drawings each of which used only a limited number of depth

cues. These were height in plane, interposition and relative size. Each

picture showed a man and a deer at the front

and an elephant at the

back in different combinations, i.e. Mundy
-
Castle discovered that the

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children’s interpretations were significantly different from those made by a
similar sample of European children. The Ghanaian children were unable to
use such

depth cues as the road to interpret the picture. Their culture did not
give them experiences of roads (and deer


they called these goats or similar)
and thus influenced their perception. Similar findings into (faulty) depth
perception have been found whe
n people are transposed out of their own
environment into an alien one.


Social and emotional influences on perception


Culture is bound up in our social world which itself provides the
circumstances within which we feel and express emotions. When New Lab
our
came to power in the late 1990s, Lord Irvine became the Lord Chancellor and
speaker of the House of Lords, head of the English legal system and a
member of the Cabinet. He set about refurbishing his official residence at
taxpayers’ expense and could no
t understand the public reaction to his
spending tens of thousands of pounds on wallpaper, chairs and curtains.
Because of the affluent and privileged social world he lived in, his perception
of what was spent on what was entirely different from that of th
e vast
majority of the population.


Allport (1955) reports on a study concerning the influence of our social world
regarding prejudice and perception. Prejudices arise from the social world we
find ourselves in. Prejudice is thus learnt


formally and info
rmally.
Prejudice influences perception. Using a stereoscope (a device for presenting
a separate picture to each eye simultaneously), the experimenters showed
participants mixed
-
race pairs of individuals; one member of each pair shown
to each eye. Generall
y people were better and more definite when picking out
and categorising members of their own race. They were more unsure and
cagey when categorising people of other ethnic groups. Afrikaaners, long
noted for their prejudice against black people, different
iated far more quickly
and definitively between the different ethnic peoples presented via the
stereoscope. They had a very definite perception and raised emotional
awareness regarding differing racial groupings. Allport interpreted this as
showing that th
e strongly racist views held by Afrikaaners had influenced
their perception.


In 1948 Postman, Bruner and McGinnies discovered using a tachiscope

that sexual and other taboo words had a higher recognition level than
ordinary language. Participants took lo
nger to process these types of

words than neutral ones. Postman et al suggest that this longer

processing time is a type of perceptual defence


to defend us from the
unacceptable. However, Bitterman and Kniffin (1953) found that the

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time difference di
sappeared if participants were allowed to write down these
taboo words. They said that Postman’s earlier work suffered from a
methodological response bias. Participants were simply less willing to say
swear words aloud than neutral words. So who is the mor
e correct?


Worthington (1969) subliminally presented participants with taboo words


so subliminally that participants were completely unaware of their
presentation. They were cleverly embedded at the centre of a dot of light
projected on to a screen. Dot
s were presented in pairs and the participants had
to say which dot was brighter, dimmer or were they both the same? Dots with
taboo words embedded on them were consistently rated as being dimmer than
those with neutral words. The perceptual defence argume
nt therefore has
some merit.


Carpenter, Weiner and Carpenter (1956) engaged participants in the
completion of sensitive topics such as personal inadequacy, sex, hostility, etc.
They categorised participants as either ‘sensitive’ or ‘repressed’ as a result
.
Sensitive participants perceived taboo or disturbing words more easily;
repressed participants perceived such words less readily and quickly.
Personal differences in values and attitudes can thus greatly influence
perception. These we get from our social

world.


Solley and Haigh (1958) reported on a study to show the influence emotion
has on perception. Children were asked to draw pictures of Santa Claus in
December and January. Representations were larger and included more
presents in the month of Decemb
er in comparison to January. In January the
drawings shrank and the presents got fewer! Solley and Haigh (1958) imply
that emotions such as excitement and anticipation can influence perception.


In 1951 Lazarus and McCleary conducted an experiment that had

them give
mild electric shocks to participants when presented with a nonsense syllable.
This provoked an avoidance response to them in the future! Interestingly they
also found an avoidance response when participants came across the nonsense
words sublimi
nally. This implies that the perceptual system works at both a
conscious and an unconscious level and that consciously and unconsciously
our perception of our world can be influenced by previous experiences.



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Perception and advertising


Advertising makes

its money by attracting our attention to products their
clients want us to buy. Very often there is in reality very little to differentiate
between similar products. One need only consider soap powder to appreciate
this point. So what makes us choose betw
een one brand and another? Whether
we notice it in the first place is the first step in the process. Getting our
attention and then changing our perception is what advertising is all about.
You cannot perceive something without attending to it. You cannot
attend to
something without perceiving it.


Please read the two extracts from the BBC website and answer the questions
that follow.



Monday 29 March 1999 published at 12:42 GMT



Ads make French Connection


Fashion retailer French Connection has announ
ced a 27% jump in
profits on the back of its controversial ‘FCUK’ advertising campaign.
The company, which owns the Nicole Farhi brand, said pre
-
tax profits
for the year to January rose to £10.4m ($16.3m) from £8.2m a year ago,
well up on market expectatio
ns. Sales grew 25.2% to £117.3m, assisted
by the opening of 10 new stores. Like
-
for
-
like sales, excluding the
effects of the new store space, were 11% higher. The company said its
decision two years ago to abbreviate its full name, French Connection
UK; to

FCUK has had an impact on customers. Its recent Christmas
advertising campaign,
FCUK Christmas


Take Me Away
, further
‘created attention and provoked discussion’, the company said.


‘Great optimism’


Chief executive Stephen Marks, said: ‘At the core of

our recent

success have been the advertising campaigns for both French
Connection and Nicole Farhi. Overall we enter the new year with

great optimism.’ He added that sponsorship of boxer Lennox Lewis

in his recent world heavyweight bout with Evander Ho
lyfield, which
saw Lewis wear the FCUK logo on his shorts, had seen its sales of
similarly branded T
-
shirts soar. In Britain the company says its
businesses are ‘performing well in what continues to be very

difficult market conditions’, Mr Marks said, whi
le the US retail

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business ‘is well ahead of last year at this stage’. The group has 88
stores in the UK and US and aims to have 109 open by January next
year. New shops have been opened in London, across the UK and in
Washington. Four outlets are set to
open in New York.


September 1999



Warning to advertisers over ‘f
-
word’


The Advertising Standards Authority is urging magazines and poster
companies not to run advertisements for a clothing firm, French
Connection, which make a play on the ‘f
-
word’. The

ASA has upheld 26
complaints about the campaign, which uses the slogan ‘f.c.u.k.
advertising’. The authority says it has brought advertising into
disrepute. The company says it has registered ‘fcuk’ as the trademark of
French Connection UK and claims that

means it must be acceptable. It
told the authority that it had responded to previous complaints about its
posters by putting dots between the initials and separating the words
‘fcuk’ and ‘advertising’ with a picture. But in its magazine
advertisement, whi
ch appeared in style titles such as
Vogue
,
Marie
Claire

and
FHM
, no alterations were made. The company said it saw no
need because these magazines often contained strong language in their
editorial features.


The ASA said without the use of dots, most rea
ders would mistake the
advertisers’ initials for the f
-
word


and it considered the campaign
brought advertising into disrepute. It has now urged media companies
not to accept the advertisements in future. ASA spokesman Chris Reed
said: ‘It’s very unusual
for us to take this action on the grounds of taste
and decency. Our research shows 77% of the public do not believe the
f
-
word should be used on advertising. We are sending out a message to
advertisers to be careful.’ Lilli Anderson, French Connection
spok
eswoman, criticised the ruling as ‘undemocratic’ and said she
thought it would have little impact on their ability to run their next
adverts, which were already being placed in magazines for the spring.
‘We’ve sold 85,000 T
-
shirts with “fcuk fashion” on th
em. If that many
people want to wear it across their T
-
shirts, to uphold a complaint by 26
people is not very democratic,’ she said.




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Student Activity


1.

What material success did French Connection UK have as a result
of their name change?


2.

What di
d the company put this success down to?


3.

What criticisms did the Advertising Standards Authority make of
the company name change?


4.

Despite these criticisms, psychologically what must have
happened from the perspective of the potential consumer?


5.

W
hen confronted for the first, second or even third time with the
stimuli, what cognitively happened for the unaware consumer?


6.

What happened to their buying behaviour?


7.

Using your knowledge of perception explain the success of this
campaign.



Disc
ussion point

Think about something you looked forward to for a long time.

What mental representations did you have in anticipation of it? What
emotions did you feel? Was the event as brilliant as you first perceived
it to be?



Student Activity


Describe a
nd explain cultural, social and developmental influences on
perception.





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Student Activity: Interactive



What is this picture? As you search for meaning in it, your brain
strives to make sense of the seemingly meaningless spots. If, after a
while
, you still see no meaning in the picture read the answer below.
Once you ‘see’ the solution, it will never again be meaningless to you.


So what’s going on?

This experiment shows that past experience can affect your perception
of such properties as form
or depth. Consider what happens when you
view this illustration. At first most people cannot tell what it depicts,
but with continued inspection or a hint, the fragments suddenly are
perceptually reorganised and recognised, in this case, as a Dalmatian
dog
. A recognisable image emerges that had no perceptual reality
before. Hence, there is some sort of perceptual change among the
neurons in your brain. This also leads to a change in the way in which
you perceive the shape and depth of the scene. Perhaps mos
t
importantly, the figure now looks like the object it was supposed to
represent


it now has the shape and depth relations of a Dalmatian dog.


Sometimes being told that a Dalmatian hides in this scene can provide
the visual system with enough of a hint t
o recognise the dog. This is a
case in which a high
-
level brain area underlying language
comprehension tells a lower
-
level area, in this case the cortical areas
dedicated to visual scene analysis, what might be going on. This is
another example of why the
study of cognitive psychology should be
seen holistically.


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If this dog were animated, it would be immediately apparent. Common
motion of a group of otherwise unrecognisable blobs is a very powerful
cue for our visual system. It enables our visual system
to realise that
it’s dealing with a single object. This effect is termed grouping. It is
important that an animal can do this well, otherwise it might not easily
spot a predator, prey or other food. Animals must be able to separate
the figure from the grou
nd. What we call camouflage is an attempt to
deceive these processes. A stalking cat moves cautiously and freezes
from time to time to avoid giving motion clues to its prey. It has even
been suggested that our good colour vision evolved to enable our
prim
ate ancestors to spot coloured fruit against a confusing background
of green leaves. What gives us so much visual pleasure may originate as
a device to spot our food and to break camouflage.


In most illustrations, we tend to perceive a figure that stands
out from
the background. In printed material, the figure is usually darker than its
background. Figures also tend to be smaller and more regular than
backgrounds. Sometimes these principles do not hold, and we have
difficulty distinguishing figures from t
heir backgrounds. However, this
difficulty disappears when our brain somehow organises these difficult
visual images into a meaningful and recognisable pattern. When this is
done, only the figure and background can be seen, and whatever was
seen before is
gone forever! Once you understand what is being
presented, your perception changes, and you will be fixed on the
‘correct’ interpretation forever.


Since these types of figure/ground figures do not lead to immediate
identification, the mental recognition
of the ‘correct’ figure must be
perceptual in character. After all, the image does not change on your
retina. Thus we can assume that some mental process that precedes or
accompanies the moment of recognition entails a perceptual
reorganisation.


Second
experiment

Now that you have recognised the Dalmatian dog, try perceiving

the image in its original meaningless way. You will find it almost
impossible to do. The picture becomes permanently meaningful.

This is in contrast to an ambiguous figure that ha
s two equally

likely interpretations. The ambiguous figure will ‘flip’ between

two states, because your brain cannot decide which one is more
meaningfully biased than the other one. In the case of the

Dalmatian dog, however, once your brain perceives t
he ‘correct’

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image and ascribes meaning to the picture, your brain will not be able
to perceive a meaningless image again, because the meaningless
interpretation is no longer equally biased with that of your past
experience with Dalmatian dogs. During al
l the time you were staring at
the picture, the image on your retina did not change. Rather, your brain
worked to construct a correct interpretation of the image, trying out
different interpretations, until your brain ‘recognised’ something. This
emphasis
es that perception is an active process of constructing a scene
description.





Student activity


Conduct an experiment using the Dalmatian dog stimuli to test the
hypothesis H1: ‘That previous past experience influences perception.’


Revise how to wr
ite up a psychological research investigation and visit
http://www.uwsp.edu/psych/apa4b.htm









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Attention


In consideration of the key concept of attention, the Scottish Qualifications
Authority say that for Psychology at Advanced Higher level we cons
ider:




an information processing approach to the study of attention



models of focused and divided attention



theories and research regarding focused auditory and visual attention


visual search, schemas



performance deficits in everyday attention.


By the end of this key concept you should be aware that attention is an
important information process, closely related to perception. Our natural state
of attention is divided attention. This is where we are able to attend to, and
deal with, lots of infor
mation in our world at one and the same time. On the
other hand, we also have an ability to focus on, or selectively attend to,
particular stimuli, while ignoring all others


at least at a conscious level.
This implies that sometimes even that to which we

do not attend directly can
still be attended to indirectly. What we attend to, and what we do not attend
to, is influenced a great deal by just how meaningful a particular stimulus is
for us. Attention is also affected by our motivation, expectations, emo
tion
and culture. The close relationship between perception and attention will be
explored in the context of active information processing. Different theories
and models of visual and auditory attention will be looked at to give us a
greater understanding
of our various states of attention, which we use
interchangeably on an everyday basis.


What is attention?


Our definition of attention is perhaps entirely appropriate. Attention is


‘… the taking possession by the mind in clear and vivid form, of one o
f
what seems several simultaneously possible objects or trains of thought.
Focalisation, (and the) concentration of consciousness are of its essence.
It implies withdrawal from some things in order to deal effectively with
others.’

William James (1890)


A study of the information process of attention first involves us in
considering four areas: selected or focused attention; divided attention;

and (as a consequence) the objective and subjective factors associated

with why we att
end to some stimuli to the exclusion of others. It must

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be emphasised that attention is closely related to perception in the family of
cognitive processes in that



The topics of perception and attention merge into each other since both
are concerned wi
th the question of what we become aware of in our
environment. We can only perceive things we are attending to and attend
to things we perceive.’

Greene and Hick (1984)



As hopefully you are aware by now, cognitive psychology is dominated by
what is call
ed an ‘
information
-
processing paradigm
’. We study information
processes like perception, attention, language, memory and thinking from the
point of view of the information processes involved, in terms of
models

of
what we think is involved.


The study of
attention therefore sees psychologists looking at two main areas:




focused
or

selective attention
, where attention is seen in terms of the
mechanisms by which certain information is registered by us, while other
information is disregarded (and whether or

not it enters our
consciousness);




divided
or
capacity attention
, where the study of attention concentrates
on the upper limit to the amount of processing that we can perform on
incoming stimuli at any one time.


How do we study attention?


Cognitive
psychology almost exclusively adopts the experimental method as
its prime research methodology. In their laboratory research into attention,
cognitive psychologists utilise a number of interesting strategies:




shadowing
: where in the study of attention p
articipants are presented with
a message into one ear, and almost immediately repeat it back;




dichotic listening tasks
: where a message is simultaneously presented to
the left ear, and a different message to the right.

Participants

are asked, for
exampl
e, to attend to and repeat back one message only;


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the
dual
-
tasking technique
: used to study divided attention where
subjects are presented with a variety of incoming stimuli and are asked to
respond to one, some or all of them. Task performance is fou
nd here to be
affected by task, similarity, task practice and task difficulty. A deficit in
our performance, sometimes called a
performance deficit
,

may be evident
as a result.


Theories of focused or selective attention


Attention, like all our cognitive

processes, is a hypothetical construct. This is
the name given to things we study in psychology that don’t actually exist in a
physical, or real, form. Thus in order to study the hypothetical construct of
attention we use
models

of what we think is happen
ing when we attend to
stimuli.


Theories on focused attention (how we seem to attend to some stimuli to the
exclusion of others) have traditionally argued in their models that somewhere
along the attention information
-
processing pipeline there is a ‘bottle

neck’,
where we have to filter out unwanted messages (or deal with them to only a
limited degree), in order to allow the passing through of more important
messages to our higher
-
level processing system. Indeed, the absence of this
probably innate neurolog
ical ability would make life impossible. We would
be bombarded with stimuli and unable to work out what ones need dealing
with first in order for us to operate successfully in our world.


The aptly named
single
-
channel theories

of attention put forward by

the
likes of Broadbent, Deutsch and Deutsch, Treisman and Norman primarily
differ over
where

this filter is, and how much and what it is we process of any
non
-
attended stimuli.


Focused auditory attention


Broadbent’s filter model (1958)

The study of atte
ntion began in earnest for cognitive psychology in 1958 with
the publication of Broadbent’s paper ‘Perception and Communication’. Felt
by many to be a cornerstone theory in cognitive psychology, Broadbent
attempted to answer in part Cherry’s earlier 1953 c
ocktail
-
party phenomenon,
with a theory about how he thought we could focus our attention on one
conversation, whilst ignoring other conversations going on around us at the
same time. The conversation we have attended to may be taking place on the
other si
de of the room! Broadbent (1958) suggests that we focus on, or
selectively attend to, stimuli on the basis of their physical properties.

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Interactive


Starting off at
http://xenia.media.mit.edu/~barons/cocktail.html

write a
report on Cherry (1953) under t
he following headings: name, date, title
of original research, method/procedure, results and conclusions.



Broadbent said our world has too many stimuli in it for us to handle at any
one time. To deal with this, we utilise a filter mechanism to process s
ome


and block out other


incoming information. As a consequence, a
bottle neck

of data (attracted to us in the first place on the basis of their physical
properties) occurs early on. What this means is that Broadbent believes we
first

attend to objects,

etc. on the basis of certain objective physical
properties that they have. Essentially these physical characteristics ‘grab’ our
attention and help us notice one stimulus more than another. Physical
characteristics important to focused or selective attent
ion include such things
as volume, brightness, intensity and novelty. These factors are well used in
the world of advertising and marketing. In order to perceive a stimulus


in
this case a product


our attention to it must somehow first be triggered.


Using a split
-
span procedure of
focused auditory attention, Broadbent
postulated that each ear acts as a
separate channel of communication
and deals with incoming aural stimuli
singularly

and
selectively
. Later
work suggested his filter model was
too simpl
istic. Indeed, there is some
evidence to suggest that he did not
satisfactorily account for the fact that
some aspects of the unattended
-
to
message during his split
-
span
procedures could be recalled by participants later. This is related to one of the
majo
r subjective reasons for us paying particular attention to some things,
e.g. how much a certain stimulus
means

to us.



Interactive


Using the same initial source as the previous Interactive, summarise
Broadbent’s (1958) research conclusions into auditory
attention.


The split
-
span procedure

Using headphones, this is where
Broadbent would present three
numbers 7, 1, 3 to one ear, at the rate
of one number per second. At the
same time, the other ear receives
another three numbers 6, 2,

4. The
participants listen to both sets of
numbers, and then write down as
many as they can recall.

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Treisman’s attenuator model (1964)


This holds with much of Broadbent’s initial single channel model of attention
but sees the bottle neck as being much more flexible. Treisman’s theory
agrees that initial screening of a stimulus occurs on th
e basis of its physical
characteristics, but instead of ‘irrelevant’ messages being disregarded, the
perceptual filter or
attenuator
turns down their volume, so to speak. They are
still available for higher
-
level processing.


‘The channel filter attenuate
s irrelevant messages rather than blocks them
completely.’

Treisman (1964)


What is particularly interesting is that Treisman’s attenuator model also
brings to our (individual) attention that further analysis is based upon
individual words, grammatical s
tructure and word meaning. It aptly deals
with an explanation for the cocktail
-
party phenomenon in that we can hear
something without attending to it and do ‘attend’ to it when it ‘means’
something to us. We seem to be able to pay attention (consciously an
d
unconsciously) more on the basis of personal meaning than the physical
characteristics of the message itself.


Treisman (1964),

‘Verbal cues, language and meaning in selective
attention’,
American Journal of Psychology
, 77: pp. 206

19


British psycholog
ist Anne Treisman, now Professor
of Cognitive Psychology at Princeton University,
revolutionised cognitive psychology with her doctoral
attenuator model
of attention in the 1960s


which
she has revised, refined and progressed ever since.
Attenuator theory

says we
can
attend to particular
stimuli even although we are not aware of them. It
built on Cherry’s ‘cocktail
-
party’ phenomenon,
influenced by criticisms of Broadbent’s earlier theory
that we consciously attend to stimuli s
olely

on the
basis of physical

properties and that we can only attend to stimuli one at a
time.


Aim:

To investigate our ability to selectively attend to a stimulus when it depends
solely on the identification of verbal or linguistic features of the message.

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Participants:

Undergradua
tes and research students at Oxford University.


Method:


Laboratory experiment.


Independent variable
: content: type and direction of messages to each ear
(the message to be attended to was sometimes switched ear
-
to
-
ear).


The content of the message,
to
be selectively attended to
, was a 150
-
word
passage of prose taken from the novel
Lord Jim

by Joseph Conrad. The
contents
(differing verbal characteristics)
of the irrelevant messages were:


I.

Prose from the same book in a man’s voice

II.

Prose from the sa
me book in a woman’s voice

III.

Prose with an insertion of Latin in a woman’s voice

IV.

Prose on a technical discussion on biochemistry in a woman’s voice

V.

French prose from a novel in the same voice as IV

VI.

German prose from a novel in the same voice
as IV

VII.

Italian prose from a novel in the same voice as IV

VIII.

‘Pigeon’ Czech in an English accent in the same voice as IV

IX.

Backwards English in the same voice as IV

X.

French translation of the
Lord Jim

shadowed message in the same voice
as IV.


P
rocedure:

Participants were engaged in a
dichotic listening task

that involves asking
participants to listen to different information in each ear.










Using a technique called
shadowing
, the
Lord Jim
message was presented, as
were the ten irrelevant
messages listed above with the participant being told
to attend to
Lord Jim

only and repeat it out loud.


Dependent variable
:
Interference on ability to recall
Lord Jim

message/recall
of attenuated messages.


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Conclusion:

That when we are in a state of fo
cused attention we selectively attend to
stimuli using what is called a filter. This filter does not work entirely on the
taxi rank

principle as previously thought. Treisman’s attenuator model (1964)
suggests that early selection/attention
is
based on phys
ical properties of the
stimulus such as pitch, loudness, etc; that attention is directed toward
information that reaches a threshold of recognition;
but

most crucially of all
that during selective attention several inputs can be processed at the same
time
.

We pay attention to unattended
-
to messages on the basis of
thresholds

we set for attending to stimuli. Important stimuli have a low threshold while
less important stimuli have a high threshold.


The inputs we can still attend to at the weak (attenuated)
level are those that
are most meaningful to us, i.e. our name and gossip about ourselves!!
Treisman’s

work then and since has demonstrated that unattended
-
to
messages are more thoroughly processed than previously thought.


She found that unknown foreign la
nguages produced less interference on
selective recall than known foreign languages, that we do seem to identify
what we are attending to, and that during the attentional process we discard
irrelevant stimuli more quickly than more meaningful information,
which is
then processed/not processed at a deeper, focused level depending on the task
on hand.


Personal meaning

is once again emphasised in the study of our information
processes.


















From Treisman (1960)


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Deutsch and Deutsch (1963); Nor
man (1969, 1976). Late selection filter
theory


Later single
-
channel theories of why we attend to certain things in particular
emphasise this is done on the basis of what is deemed
pertinent

to the
individual. This simply means that we attend to and percei
ve stimuli on the
basis of what is subjectively valid (meaning something), or important, to
ourselves. Put another way, attention/perception is influenced by selfishness!


Pertinence model theorists put the bottle neck in our ‘single channel’ of
attention

much nearer the response end of the auditory processing system.
They say, rejecting Broadbent, that we fully analyse
all
signals and pass them
on to the attenuator, which passes on the signal to be further processed but in
a more toned
-
down form. We atten
d to certain things more than others
because something about them is more relevant for us. The pertinence model
suggestion that we analyse everything has been criticised by Solso and
Professor Michael Eysenck as too rigid and inflexible. In general terms,
criticisms of the Pertinence Model are worries about a single all
-
purpose,
limited capacity, central processor. Single
-
channel theory seems too all
-
inclusive a theory to account for the complexities involved in the unique
human experience of attention.



Interactive


Read Chapter 5 of
Cognitive Psychology

by Richard Gross and Rob
McIlveen (Hodder & Stoughton).


Discuss and evaluate single
-
channel theory in the light of focused
auditory attention.



Focused visual attention


Investigation into focused vi
sual attention has looked primarily at three main
areas:




unilateral neglect



extinction; and



Balint’s syndrome.



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Unilateral neglect

Unilateral neglect (UN) occurs as a result of brain damage to the right
parietal lobe. It manifests itself where vic
tims, for example when copying a
drawing, leave out everything on its left
-
hand side. They cannot account for
stimuli in their left visual field. Unilateral neglect patients show a similar
behaviour when asked to perform tasks involving visual imagery (Bis
iach and
Luzzatti, 1978). Lately it has been discovered that some processing of
neglected stimuli does actually occur. Marshall and Halligan (1988) presented
a UN patient with a drawing of two identical houses side by side. The only
difference was that the

one on the left
-
hand side had flames coming out of the
windows. The patient could not report any difference between the two
drawings, but
did

say that she would prefer to live in the house on the right
-
hand side!


Why this phenomenon occurs is still a b
it of a mystery. Parkin (1996) reports,
‘… the idea that a single theory of neglect will emerge is highly unlikely
because of the diversity of defects being discovered.’




Interactive


Read a review of
Unilateral Neglect: Clinical and Experimental Stud
ies
,
edited by Robertson and Marshall at

http://psyche.cs.monash.edu.au/v1/psyche
-
1
-
08
-
walker.html


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Extinction

Extinction is a symptom found in some unilateral neglect patients. These
patients can attend to stimuli when presented normally to either their

left or
right visual field. But when the two stimuli are presented side by side, the
one nearer the side of the visual field that is neglected goes undetected.


Balint’s syndrome

Balint’s syndrome comes about due to damage in both cerebral hemispheres
in
volving the posterior parietal lobe or parietal
-
occipital junction. Balint’s
syndrome patients exhibit a variety of attentional difficulties including fixed
gazing, over
-
extending for objects and
simultagnosia
. Simultagnosia is when
only one object at a ti
me can be seen (Humphreys and Riddoch, 1993). In
this research, when Balint’s syndrome participants were shown a number of
red and green circles, they were generally unable to see both coloured circles
simultaneously. They could, however, identify them w
hen they became one
‘whole’ object joined together by lines.



Simultagnosia





Red

Green

Red

Green





Humphreys and Riddoch (1993)


While there is no one agreed theory as to the cause of simultagnosia, Driver
(1998) suggests that the main problem

for Balint’s patients is their inability
to disengage covert attention from an object. Covert attention is when our
attention moves without the eyes, often as a precursor to a saccade, which can
be either endogenously or exogenously controlled. Some expl
anations:


Endogenous

(controlled) attention


this is usually a movement of

covert attention that isn’t elicited by something in the environment (such

as a sudden flash) but by the individual who knows where they need to

look next. For example, when re
ading we know that we have to move

our eyes along a line of text from left to right. Because we have

knowledge about a predictable environment, our attention can be

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directed to the right of fixation (up to fourteen letters) to help guide our
reading.


Exogenous

(automatic) attention


an abrupt onset (e.g. a flash of light in
peripheral vision can capture covert attention. This usually results in a
saccade to the flash area to have a look what is there).


Saccade



a movement of the eye. When the eye mo
ves, no information is
taken in until it lands and a new fixation is started.


Source:
http://www.psychology.nottingham.ac.uk/staff/dec/c8cllc/l13
-
16glossary.doc


Elements to visual attention


In an attempt to discover the components of visual attention, P
osner and
Pederson (1990) reviewed findings from such attentional disordered patients.
They argue that our ability to visually attend involves three separate
processes.




we have an ability to disengage our attention from one stimulus to another.
This com
ponent of visual attention is called
disengagement
;




we also use
shifting,

which is our ability to move our attention from one
stimulus to another;




we use the process of
engaging
, or ‘locking’ on to new visual stimuli.


A ‘spotlight’ model of visual

attention

The spotlight model of visual attention is considered by the likes of Driver
(1996) and LaBerge (1983). It is a model that holds that we adopt a broader
attentional beam, depending on the visual task; that when we visually attend
to stimuli, our

visual attention can be likened to an internal mental spotlight
that mostly concentrates on the centre of whatever it is we are visually
attending to. We visually attend less to what might be going on at the
periphery of our visual scene. When we have to
process this peripheral visual
information, we have to shift the spotlight. The idea that no processing occurs
beyond the periphery of the spotlight has been confirmed by, amongst others,
Johnston and Dark (1986).


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The ‘zoom
-
lens’ model of visual attenti
on

The ‘spotlight’ model precipitated the development of the zoom
-
lens model
of visual attention. Erikson (1990) accepts the existence of the idea of an